Long-term implications of feed energy source in different genetic types of reproductive rabbit females: I. Resource acquisition and allocation

To achieve functional but also productive females, we hypothesised that it is possible to modulate acquisition and allocation of animals from different genetic types by varying the main energy source of the diet. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66), a maternal line characterised by hyper-prolificacy; LP (n=67), a maternal line characterised by functional hyper-longevity; R (n=79), a paternal line characterised by growth rate. Females were fed with two isoenergetic and isoprotein diets differing in energy source: animal fat (AF) enhancing milk yield; cereal starch (CS) promoting body reserves recovery. Feed intake, weight, perirenal fat thickness (PFT), milk yield and blood traits were controlled during five consecutive reproductive cycles (RCs). Females fed with CS presented higher PFT (+0.2 mm, P<0.05) and those fed AF had higher milk yield (+11.7%, P<0.05). However, the effect of energy source varied with the genetic type and time. For example, R females presented a decrease in PFT at late lactation (−4.3%; P<0.05) significantly higher than that observed for H and LP lines (on av. −0.1%; P>0.05), particularly for those fed with AF. Moreover, LP females fed with AF progressively increased PFT across the RC, whereas those fed with CS increased PFT during early lactation (+7.3%; P<0.05), but partially mobilised it during late lactation (−2.8%; P<0.05). Independently of the diet offered, LP females reached weaning with similar PFT. H females fed with either of the two diets followed a similar trajectory throughout the RC. For milk yield, the effect of energy source was almost constant during the whole experiment, except for the first RC of females from the maternal lines (H and LP). These females yielded +34.1% (P<0.05) when fed with CS during this period. Results from this work indicate that the resource acquisition capacity and allocation pattern of rabbit females is different for each genetic type. Moreover, it seems that by varying the main energy source of the diet it is possible to modulate acquisition and allocation of resources of the different genetic types. However, the response of each one depends on its priorities over time.     

Improvements in the conception rate,milk composition and embryo quality of rabbit does after dietary enrichment with n-3 polyunsaturated fatty acids

This work attempts to confirm the effect of an enriched diet with n-3 polyunsaturated fatty acids (PUFA) trying to mitigate the reproductive performances issues such as low conception rate of primiparous rabbits. A total of 127 does were fed ad libitum throughout their two first cycles with two diets with different fat sources: mixed fat in the control and salmon oil in the enriched one, with 3.19 g/100 g (n=63 does) and 28.77 g/100 g (n=64 does) of n-3 of the total fatty acid, respectively. Feed intake was similar between groups (P>0.05). Plasma progesterone concentration was higher in the enriched females than in control ones at 7 (30.9±2.18 v. 23.9±2.30 ng/ml, respectively; P=0.029) and 14 (38.7±2.18 v. 28.2±2.30 ng/ml, respectively; P=0.001) days of first gestation. Considering both cycles, reproductive parameters of mothers (fertility, duration of gestation and prolificacy) and litter parameters (weight at parturition and weaning, mortality and average daily gain (ADG) of kits during lactation) were similar in both groups. However, individual measurements of neonates of enriched group improved 5.87%, 7.10% and 18.01% (P<0.05) in terms of crown-rump length, biparietal and thoracic diameters, respectively, compared to control ones at first parturition. It is noteworthy that at the second insemination, critical point in rabbit, fertility rate of enriched group did not decline as sharply as in the control group (89.7% v. 76.6%, respectively; P=0.067), although ADG and littler weight were slightly lower at the second lactation after PUFA enrichment (P<0.05). Total PUFA and unsaturated index of milk of enriched does group were significantly elevated than in control one (33.3±0.02 v. 23.2±0.02 g/100 g and 1.20±0.00 v. 0.86±0.00, respectively; P<0.05). Finally, plasma progesterone, ovulation rate, fertility and embryo development at 3.5 days after the artificial insemination were similar between diets (P>0.05), but embryo apoptosis rate was higher in control group than in enriched one (31.1±4.56% v. 17.1±3.87%, respectively; P<0.05). In conclusion, dietary PUFA enrichment from the rearing and throughout two productive cycles improved plasma progesterone during pregnancy, fertility, milk fatty acid profile and neonates development of primiparous supporting the beneficial effect of n-3 PUFA supplementation in rabbit does.     

Supplementing sow diets with palm oil during late gestation and lactation: effects on milk production,sow hormonal profiles and growth and development of her offspring

The supplementing of sow diets with lipids during pregnancy and lactation has been shown to reduce sow condition loss and improve piglet performance. The aim of this study was to determine the effects of supplemental palm oil (PO) on sow performance, plasma metabolites and hormones, milk profiles and pre-weaning piglet development. A commercial sow ration (C) or an experimental diet supplemented with 10% extra energy in the form of PO, were provided from day 90 of gestation until weaning (24 to 28 days postpartum) in two groups of eight multiparous sows. Gestation length of PO sows increased by 1 day (P<0.05). Maternal BW changes were similar throughout the trial, but loss of backfat during lactation was reduced in PO animals (C: −3.6±0.8 mm; PO: −0.1±0.8 mm; P<0.01). Milk fat was increased by PO supplementation (C day 3: 8.0±0.3% fat; PO day 3: 9.1±0.3% fat; C day 7: 7.8±0.5% fat; PO day 7: 9.9±0.5% fat; P<0.05) and hence milk energy yield of PO sows was also elevated (P<0.05). The proportion of saturated fatty acids was greater in colostrum from PO sows (C: 29.19±0.31 g/100 g of fat; PO: 30.77±0.36 g/100 g of fat; P<0.01). Blood samples taken on 105 days of gestation, within 24 h of farrowing, day 7 of lactation and at weaning (28±3 days post-farrowing) showed there were no differences in plasma concentrations of triacylglycerol, non-esterified fatty acids, insulin or IGF-1 throughout the trial. However, circulating plasma concentrations of both glucose and leptin were elevated during lactation in PO sows (P<0.05 and P<0.005, respectively) and thyroxine was greater at weaning in PO sows (P<0.05). Piglet weight and body composition were similar at birth, as were piglet growth rates throughout the pre-weaning period. A period of 7 days after birth, C piglets contained more body fat, as indicated by their lower fat-free mass per kg (C: 66.4±0.8 arbitrary units/kg; PO: 69.7±0.8 arbitrary unit/kg; P<0.01), but by day 14 of life this situation was reversed (C: 65.8±0.6 arbitrary units/kg; PO: 63.6±0.6 arbitrary units/kg; P<0.05). Following weaning, PO sows exhibited an increased ratio of male to female offspring at their subsequent farrowing (C: 1.0±0.3; PO: 2.2±0.2; P<0.05). We conclude that supplementation of sow diets with PO during late gestation and lactation appears to increase sow milk fat content and hence energy supply to piglets. Furthermore, elevated glucose concentrations in the sow during lactation may be suggestive of impaired glucose homoeostasis.     

Effects of feeding programme on the performance and energy balance of nulliparous rabbit does

A total of 190 rabbit females were used to evaluate five feeding programmes from 9 weeks of age to the first parturition: CAL, fed ad libitum with a control diet (C: 11.0 MJ digestible energy (DE) and 114 g digestible protein (DP)/kg dry matter (DM)) until first parturition; CR, fed ad libitum with C diet until 12 weeks of age and then C diet restricted (140 g/day) until first parturition; F, fed ad libitum with a low-energy, high-fibre diet (F: 8.7 MJ DE and 88 g DP/kg DM) until first parturition; FC, fed with F diet ad libitum until 16 weeks of age, and C diet ad libitum until first parturition; FCF, fed with F diet ad libitum until 16 weeks of age, then C diet ad libitum until 20 weeks and then F diet ad libitum until first parturition. The rabbits were artificially inseminated at 18 weeks of age. CAL group had a higher mortality rate compared with the other groups between 9 and 12 weeks of age (34% v. 3%; P < 0.05) and during the last 3 weeks of first pregnancy (14% v. 3%; P < 0.05). The CAL and FC females presented higher BW and perirenal fat thickness (PFT) than CR females at 11 days of pregnancy (+0.41 kg and +0.6 mm; P < 0.05), with F females showing medium values. The type of feeding procedure did not affect the fertility rate of young females at first artificial insemination. Differences in BW disappeared at parturition, when only CAL females presented a greater PFT than CR and FC females (+0.3 mm; P < 0.05). In comparison with FCF, CAL females had smaller and thinner live born litters (−2.5 kits and −139 g, respectively; P < 0.05), with CR, F and FC females showing medium values. The low number of kits born alive for CAL females was because of their lesser total number of kits born (−1.7 kits; P < 0.05) and the greater mortality of their litters at birth (+13.9%; P < 0.05) compared with FCF females. Non-esterified fatty acid was higher in the blood of females fed C diet (CAL and CR) than in others at partum day (on average +0.15 mmol/l; P < 0.05). In conclusion, the ad libitum use of diets for lactating rabbit does throughout the rearing period could lead young rabbit females to present a higher risk of early death and smaller litter size at first parturition. Feed restriction or earlier use of suitably fibrous diets led females to achieve the critical BW and fat mass at first mating to ensure reproduction.     

Consequences of rearing feeding programme on the performance of rabbit females from 1st to 2nd parturition

To evaluate how rearing programmes could affect resources allocation and reproductive performance of primiparous rabbit females, a total of 118 rabbit females were used to evaluate the effects of five rearing feeding programmes on their performance from 1st to 2nd parturition: CAL, fed ad libitum C diet (11.0 MJ digestible energy (DE), 114 g digestible protein (DP) and 358 g NDF/kg dry matter (DM) until 1st parturition; CR, fed ad libitum with C diet until 12 weeks of age and then C diet restricted (140 g/day) until 1st parturition; F, fed ad libitum with F diet (8.7 MJ DE, 88 g DP and 476 NDF/kg DM) until 1st parturition; FC, fed with F diet ad libitum until 16 weeks of age, and C diet ad libitum until 1st parturition; FCF, fed with F diet ad libitum until 16 weeks of age, then C diet ad libitum until 20 weeks and then F diet ad libitum until 1st parturition. From 1st parturition, C diet was ad libitum offered to all the experimental groups until 2nd parturition. CAL females presented lower feed intake than females of F, FC and FCF groups in the 1^st week of lactation (on av. −16.6%; P<0.05). During 1st lactation, the perirenal fat thickness change in CAL females was not different from 0 (+0.02 mm), while in the other four groups it increased (on av. +0.44 mm; P<0.05). Plasma of females fed with F diet during rearing (F, FC and FCF) had lower non-esterified fatty acids content than those exclusively fed with C diet (–0.088 and –0.072 mmol/l compared to CAL and CR, respectively; P<0.05). FCF litters had higher weight than F litters at day 21 of lactation (+247 g; P<0.05), but FCF litter had significantly lower weight than FC litters at weaning (+170 g; P<0.05). CR females had the shortest average interval between the 1st and 2nd parturition (49 days) and FCF females the longest (+ 9 days compared to CR; P<0.05). At 2nd parturition, liveborn litters of F females were larger and heavier than litters of FCF females (+2.22 kits and +138 g; P<0.05), probably due to the lower mortality at birth of F litters (–16.5 percentage points; P<0.05). In conclusion, rearing females on fibrous diets seems to increase the ability of primiparous rabbit females to obtain resources, especially at the onset of lactation.     

Effects of different amounts and type of diet during weaning-to-estrus interval on reproductive performance of primiparous and multiparous sows

During weaning-to-estrus interval (WEI), the sows are usually fed with high feed level to improve the reproductive performance. However, the WEI has been reduced over the years which may reduce the impact of feed level on performance in the modern genetic lines. The aim of this study was to evaluate the effect of two feeding levels (moderate feeding level (MFL): 2.7 kg/day and high feeding level (HFL): 4.3 kg/day) and two diet types (gestation: 13.67 MJ/kg of metabolizable energy (ME) and 0.62% of standard ileal digestible lysine (SID Lys) and lactation: 14.34 MJ ME/kg and 1.20% of SID Lys) offered during the WEI on reproductive performance. In total, 19.0% of sows were excluded from the analysis due to feed intake below 75% (9.6% and 28.5% in MFL and HFL groups, respectively), remaining 254 primiparous and 806 multiparous sows. Follicular size and change in BW were measured in subsamples of 180 and 227 females, respectively. Data were analyzed considering the sow as the experimental unit. Feeding level, diet type, parity and their interactions were included as fixed effects, whereas the day of weaning was considered as a random effect. The feed intake of MFL and HFL groups averaged 2.5 ± 0.02 and 3.8 ± 0.02 kg/day, respectively. There was an interaction between feeding level and parity for daily feed intake. Within HFL, multiparous sows consumed 181 g/day more than primiparous sows (P < 0.01), but no difference was observed within MFL (P > 0.05). Both primiparous and multiparous sows lost proportionally less weight when fed HFL than MFL gestation diet during WEI. The percentage of weight loss was lower in HFL than in the MFL group in multiparous sows fed the lactation diet. The WEI was not affected by feeding level, diet type or its interaction (P > 0.05), but it was longer in primiparous than in multiparous sows (P = 0.001). There was no effect of feeding level, diet type, parity or their interactions on anestrus and farrowing rates. Multiparous sows showed greater follicular size, and greater numbers of total born and born alive piglets in the subsequent cycle than primiparous sows (P < 0.05). In conclusion, feeding weaned primiparous and multiparous sows with 4.3 kg/day of a gestation (58.78 MJ ME and 26.66 g SID Lys) or a lactation diet (61.66 MJ ME and 51.60 g SID Lys) does not improve follicular size and reproductive performance in the subsequent cycle.     

Estimates of genetic parameters and genetic trends for growth,reproduction, milk production and milk composition traits of Awassi sheep

Genetic parameters and genetic trends for growth, reproduction, milk production and composition traits were estimated for Syrian (S) and Turkish (T) Awassi sheep and their crosses maintained at the International Center for Agricultural Research in the Dry Areas Tal Hadya station, Aleppo, Syria (now in Terbol station in Lebanon). The data were spread over 9 years. The individual breed additive effects of T were positive and significant (P<0.05) for birth weight (BW). However, the values for weaning weight (WW) and pre-weaning weight gain (WG) were negative, even though they were significant (P<0.05). These estimates were positive and significant (P<0.05) for all reproduction and milk traits, except for litter weight at birth (LWB). The additive contributions of T were 60.72±0.94 days, 1.643±0.359 kg, 13.09±0.89 days, 16.13±0.89 kg, 1.12±0.44 kg, 0.71±0.26 kg, 2.80±0.72 kg and 0.83±0.32 kg for lambing interval (LI), litter weight at weaning (LWW), lactation length, milk yield, fat yield, protein yield, total solids yield and lactose yield, respectively. The heterosis effects, both individual and maternal, were non-significant (P>0.05) for most growth traits. Crossing of T with S, however, resulted in desirable and significant (P<0.05) individual heterosis effects for all the reproduction, milk production and constituent yields. The heritability (h²) estimates, both direct and maternal, were low for BW, WW, WG and all reproductive traits indicating major influence of environmental factors, whereas milk yield and composition had medium values. Birth weight had moderate genetic correlation with WW and WG. The genetic correlation between WW and WG was high (0.724±0.951). Lambing interval had large negative genetic correlation with LWB and LWW. However, LI had medium significant correlations with all the milk production and composition traits. Larger litter weights at birth had high and negative influence on milk yield of the dam and its constituents. Genetic changes over years for all traits were non-significant. The lack of genetic change in the studied traits calls for systematic and organized selection scheme.     

Influence of gestational maternal feed restriction on growth performance and meat quality of rabbit offsprings

The purpose of the present study was to evaluate the effect of feed restriction during pregnancy on reproductive performance of rabbit does and growth performance and meat quality of their offspring. A total of 26 primiparous non lactating does were equally divided into two treatment groups: the control group (C, n=13) that was fed ad libitum throughout gestation and the feed restricted group (R, n=13) that was fed to 75% of maintenance energy requirements from the 7^th to the 26^th day of gestation. Rabbit offsprings were weaned at 35 days of age and grown until the 72 days of age when they were slaughtered for meat quality assessment. Meat quality traits measured were pH₂₄, colour (L*, a*, b*), percentage of released water, cook loss, shear values and intramuscular fat. At kindling, R does produced smaller litter weights compared with those of does from group C, 447.8 and 591.4 g, respectively, and smaller individual kit birth weights, 56.2 and 71.5 g, respectively (P<0.05). Ratio of stillborn kits and mortality rate from parturition until weaning was higher (P<0.05) in the R group, 21.4% and 11.1%, respectively, in comparison with the C group, 8.1% and 3.5%, respectively. Litter size and gestation length were unaffected by maternal undernutrition. Kit birth weight treatment differences were eliminated at weaning because of compensatory growth (P>0.05). Performance and meat quality characteristics of fattening rabbits at 72 days of age were not influenced by gestational feed restriction of their mothers (P>0.05). Taking into consideration that, simultaneous gestation and lactation in rabbit does may be simulated by gestational feed restriction, results of the present study suggest that lactating does can support a simultaneous gestation without any adverse effect on the offsprings’ quantitative and qualitative performance at the expense of increased mortality rates at parturition and until weaning.     

Effects of feed restriction during pregnancy on maternal reproductive outcome,foetal hepatic IGF gene expression and offspring performance in the rabbit

Primiparous female rabbits have high nutritional requirements and, while it is recommended that they are subjected to an extensive reproductive rhythm, this could lead to overweight, affecting reproductive outcomes. We hypothesised that restricting food intake during the less energetic period of gestation could improve reproductive outcome without impairing offspring viability. This study compares two groups of primiparous rabbit does in an extensive reproductive programme, one in which feed was restricted from Day 0 to Day 21 of gestation (R021), and another in which does were fed ad libitum (control) throughout pregnancy. The mother and offspring variables compared were (1) mother reproductive outcomes at the time points pre-implantation (Day 3 postartificial insemination [AI]), preterm (Day 28 post-AI) and birth; and (2) the prenatal offspring characteristic IGF system gene expression in foetal liver, liver fibrosis and foetus sex ratio, and postnatal factor viability and growth at birth, and survival and growth until weaning. Feed restriction did not affect the conception rate, embryo survival, or the number of morulae and blastocysts recovered at Day 3 post-AI. Preterm placenta size and efficiency were similar in the two groups. However, both implantation rate (P < 0.001) and the number of foetuses (P = 0.05) were higher in the R021 mothers than controls, while there was no difference in foetal viability. Foetal size and weight, the weights of most organs, organ weight/BW ratios and sex ratio were unaffected by feed restriction; these variables were only affected by uterine position (P < 0.05). Conversely, in the R021 does, foetal liver IGBP1 and IGF2 gene expression were dysregulated despite no liver fibrosis and a normal liver structure. No effects of restricted feed intake were produced on maternal fertility, prolificacy, or offspring birth weight, but control females weaned more kits. Litter weight and mortality rate during the lactation period were also unaffected. In conclusion, pre-implantation events and foetal development were unaffected by feed restriction. While some genes of the foetal hepatic IGF system were dysregulated during pregnancy, liver morphology appeared normal, and the growth of foetuses and kits until weaning was unmodified. This strategy of feed restriction in extensive reproductive rhythms seems to have no significant adverse effects on dam reproductive outcome or offspring growth and viability until weaning.     

Fertility of sows injected with exogenous oestradiol and/or gonadotrophins to control post-weaning oestrus

In the first of two experiments 28 multiparous sows were allocated to one of the following treatments 2 days after weaning at approximately 35 days post partum: (1) untreated; (2) i.m. injection 10 μg oestradiol benzoate (OB)/kg body weight (b.wt.); and (3) i.m. injection 20 μg OB/kg b.wt. Sows were bred at first post-weaning oestrus and ovulation rate assessed at slaughter. The mean interval from weaning to oestrus in each group was: (1) 5.6 ± 0.2; (2) 4.7 ± 0.2; and (3) 4.7 ± 0.2 days; the mean ovulation rates in groups 1 and 2 (18.7 ± 0.6 and 17.4 ± 1.8, respectively) were significantly higher (P < 0.01) than that of 12.0 ± 1.7 for treatment 3 sows. Two untreated and one each of the treated sows were not cycling at slaughter.In the second experiment 75 multiparous sows weaned at 28 ± 3 days post partum (day 0) were evenly allocated with respect to parity to one of four treatment groups: (1) untreated; (2) i.m. injection 10 μg OB/kg b.wt. on day 2; (3) PG600 (400 iu PMSG + 200 iu hCG) injection subcutaneous day 0; and (4) combined PG600/OB treatment as in (2) and (3) above. Sows were bred naturally at the first post-weaning oestrus and fertility assessed at farrowing. Control animals had a significantly longer (P < 0.05) weaning to oestrus interval (4.53 ± 0.25 days) compared to treatment 2 (4.03 ± 0.13) treatment 3 (3.97 ± 0.12) and treatment 4 (3.81 ± 0.07) sows. Sows treated with PG600 alone showed a significant increase (P < 0.05) in numbers born live compared to pre-treatment values. A smaller and non-significant increase in numbers born live in control sows (probably related to increasing parity) was not observed in either OB- or PG600/OB-treated animals.These results suggest that with further modification of the treatments, a system may be developed for introducing fixed-time artificial insemination (AI) or mating as a means of controlling the reproductive performance of the weaned sow.     

Effects of dietary menhaden oil on growth and reproduction in gilts farrowed by sows that consumed diets containing menhaden oil during gestation and lactation

In sows, n-3 fatty acids increase litter sizes, however, effects on gilt reproductive development have not been adequately studied. Moreover, not determined are effects of feeding n-3 fatty acids to sows on reproduction in offspring. The objective here was to determine effects of 4% dietary menhaden oil on growth and puberty in gilts farrowed by sows fed menhaden oil. Sows (n = 44) were assigned to: (1) control gestation and lactation diets, or (2) diets including menhaden oil. For primiparous sows only, total litter size and born alive were greater (P < 0.05) in females fed menhaden oil. Conversely, pigs from primiparous controls were heavier (P < 0.05) than pigs from primiparous sows fed menhaden oil (parity by diet interactions, P < 0.01). Diet did not affect (P > 0.20) other sow and litter characteristics. At weaning, 84 gilts from control- or menhaden oil sows were placed three gilts per pen and provided control diets or diets containing menhaden oil. Nursery and grow-finish feed intake and feed efficiency were similar (P > 0.21) for gilts from the different sows and weight gain was similar (P > 0.24) for gilts fed control or menhaden diets. Gilts fed menhaden oil tended to eat less in the nursery (1.18±0.08 kg v. 0.98±0.08 kg; P = 0.09) and overall (1.83±0.04 kg v. 1.72±0.04 kg; P = 0.06). Thus, overall feed to gain was greater (2.52±0.03 v. 2.33±0.03; P < 0.01) and nursery (2.12±0.04 v. 1.80±0.04; P = 0.10) and grow-finish (3.07±0.19 v. 2.58±0.19; P = 0.08) feed to gain tended to be greater, for control gilts. Age at puberty was greater (P = 0.02) for gilts from menhaden oil-fed sows (205.1±3.2 days) compared to gilts from controls (193.9±3.2 days) and tended to be greater (P = 0.09), for controls (203.5±3.2 days) compared to gilts fed menhaden oil (195.5±3.2 days). A tendency existed (P = 0.09) for greater follicular fluid in gilts fed menhaden oil, however, ovulation rate and ovarian, luteal and uterine weights were not affected by sow diet, gilt diet or the interaction (P > 0.23). Feeding gilts menhaden oil enhanced feed efficiency and hastened puberty onset. Gilts from sows consuming menhaden oil exhibited delayed puberty and retaining females from sows fed this feedstuff may be ill advised.     

Post-partum reproduction in swamp buffalo cows at two feeding levels

Post-partum progesterone secretion, oestrus, and conception were monitored in two groups of eight swamp buffalo cows which were fed at “low” or “high” levels from 12 weeks before until 36 weeks after calving. Calf birth weights and pre-weaning mortality were not affected significantly by nutritional treatment, but the average growth rates of calves from birth to weaning at 26 weeks of age were greater (P<0.01) at the high (0.39 kg/day) than at the low (0.26 kg/day) feeding level. In five cows from each group which reared calves to weaning, average post-partum intervals to first oestrus were 190 and 144 days (P<0.10), and average post-partum intervals to conception were 222 and 169 days (P<0.05), at the low and high feeding levels, respectively. Plasma progesterone profiles indicated that normal post-partum luteal function at both feeding levels was commonly preceded by transient corpora lutea with subnormal progesterone secretion. Mean body weights at conception did not differ significantly between the two groups, suggesting that earlier post-partum conception in cows at the high feeding level was associated with their lower body weight loss and/or their faster body weight recovery after calving.     

Effects of intermittent suckling on body composition of Iberian piglets weaned at 35 days of age

Piglet body composition at weaning could be a determinant for pig’s viability and may be influenced by factors such as the nutritional management followed during suckling. An experiment was conducted to study whether intermittent suckling (IS) affects body composition at weaning and nutrient and energy retention during a 34-day lactation period in Iberian piglets. Litters were subjected to conventional suckling (CS) or IS (n=10 litters of six piglets per treatment) in two trials. All piglets had ad libitum access to creep feed from day 15 onwards. In IS, piglets were progressively separated from the sow for 6, 8 and 10 h daily during the last week of lactation, whereas in CS piglets had continuous access to their dams. Creep feed intake in litters and BW development of individual piglets were measured throughout the 34-day lactation. Within each litter, both at birth and at weaning (day 35), one piglet was used to assess nutrient retention and body composition by the comparative slaughter approach. During days 29 to 35 of the experiment, daily creep feed intake was greater in IS piglets (IS 124, CS 67 g/piglet, P=0.040), and average daily gain differed significantly between groups (IS 190, CS 150 g/day, P=0.010). BW at weaning was higher in the IS than in the CS piglets (IS 8.19, CS 7.48 kg, P=0.011). Empty-body fat and energy content at weaning were higher in the IS compared with CS litters, as well as fat content in the carcass (P=0.04). The IS treatment did not affect empty-body protein deposition, but significantly increased daily retention of fat, energy, ash and calcium, compared with CS litters (P<0.05). Thus, IS in Iberian piglets seems to enhance feed intake, growth rate and retention of some body components, which may contribute to a higher body fat content at weaning and facilitate the weaning process.     

Effect of average litter weight in pigs on growth performance,carcass characteristics and meat quality of the offspring as depending on birth weight

Offspring born from normal litter size (10 to 15 piglets) but classified as having lower than average birth weight (average of the sow herd used: 1.46 ± 0.2 kg; mean ± s.d.) carry at birth negative phenotypic traits normally associated with intrauterine growth restriction, such as brain-sparing and impaired myofiber hyperplasia. The objective of the study was to assess long-term effects of intrauterine crowding by comparing postnatal performance, carcass characteristics and pork quality of offspring born from litters with higher (>1.7 kg) or lower (<1.3 kg) than average litter birth weight. From a population of multiparous Swiss Large White sows (parity 2 to 6), 16 litters with high (H = 1.75 kg) or low (L = 1.26 kg) average litter birth weight were selected. At farrowing, two female pigs and two castrated pigs were chosen from each litter: from the H-litters those with the intermediate (H_I = 1.79 kg) and lowest (H_L = 1.40 kg) birth weight, and from L-litters those with the highest (L_H = 1.49 kg) and intermediate (L_I = 1.26 kg) birth weight. Average birth weight of the selected H_I and L_I piglets differed (P < 0.05), whereas birth weight of the H_L- and L_H-piglets were similar (P > 0.05). These pigs were fattened in group pen and slaughtered at 165 days of age. Pre-weaning performance of the litters and growth performance, carcass and meat quality traits of the selected pigs were assessed. Number of stillborn and pig mortality were greater (P < 0.05) in L- than in H-litters. Consequently, fewer (P < 0.05) piglets were weaned and average litter weaning weight decreased by 38% (P < 0.05). The selected pigs of the L-litters displayed catch-up growth during the starter and grower–finisher periods, leading to similar (P > 0.05) slaughter weight at 165 days of age. However, H_L-gilts were more feed efficient and had leaner carcasses than H_I-, L_H- and L_I-pigs (birth weight class × gender interaction P < 0.05). Meat quality traits were mostly similar between groups. The marked between-litter birth weight variation observed in normal size litters had therefore no evident negative impact on growth potential and quality of pigs from the lower birth weight group.     

Influence of weaning regimen on intake,growth characteristics and plasma blood metabolites in male buffalo calves

Experiment was conducted to evaluate the effect of weaning age on growth performance, feed intake, feed efficiency (FE) and blood metabolites in Nili-Ravi male buffalo (Bubalus bubalis) calves. Twenty-four male buffalo calves were assigned to one of the three treatment groups: continuous milk feeding (CMF), limited milk feeding (LMF) and early weaning (EW), and weaned off milk at 12, 10 and 8 weeks of age, respectively. For the first 3 days after birth, calves in all three treatments were fed colostrum, and were then moved to individual milk feeding at 10% of BW for the next 6 weeks. Thereafter, the provision of milk to the CMF group was gradually tapered to zero through week 12, using week 6 intakes as a base. The LMF calves were fed milk at 7.5%, 5.0%, 3.5%, and 1.5% of BW during weeks 7 to 10, respectively. Lastly, calves in the EW group were fed milk at 5.0% and 2.5% of BW at weeks 7 and 8, respectively. Calf starter (CS) feed was also provided ad libitum from weeks 2 to 12 and individual intakes were recorded on a daily basis. Blood samples were taken from weeks 6 to 12, on a weekly basis; whereas, the BW, heart girth, withers height and hip width were measured at the start of experiment and later on a weekly basis. Weight gain, average daily gain, and body measurements were the same across all three groups. Milk intake was lower (P < 0.05), whereas CS intake was greater (P < 0.05) in the EW calves compared with the other treatment groups. Dry matter intake was greater (P < 0.05) in the EW and LMF calves compared with the CMF calves. The FE was greater (P < 0.05) in the CMF calves compared with the LMF and EW treatment groups. Blood glucose concentration was similar among the treatments; however, blood urea nitrogen was greater (P < 0.05) in the EW calves compared with the CMF and LMF groups. Plasma concentration of non-esterified fatty acids was higher (P < 0.05) in the EW calves compared with the CMF calves. In light of these results, it is evident that buffalo calves can be successfully weaned as early as 8 weeks of age without negatively affecting their growth performance.     

Effect of oral progesterone and caffeine at the end of gestation on farrowing duration and piglet growth and survival

The profitability of pig production is constrained by high incidences of peri-parturient and pre-weaning piglet mortality. Supplementing sows with either progesterone or caffeine during the last week of gestation can reduce stillbirths and improve piglet performance. However, the consequences of combining these two substances has not been investigated. The aim of the current study was to determine the effect of oral supplementation of sows with progesterone (regumate) and caffeine at the end of gestation on the timing and progression of farrowing, as well as piglet survival and growth to weaning. From days 111 to 113 of gestation, 20 Large White pregnant sows (parity 3.0±0.45) received 5 ml of Regumate Porcine (0.4 w/v oral solution; MSD Animal Health) daily on top of their morning ration. Sows were stratified according to parity and predicted farrowing date, and allocated at random to receive a diet supplemented with either 0 g caffeine/kg diet (CONT) or 2.4 g of caffeine/kg diet (CAFF) from day 113 of gestation until parturition (n=10 sows/treatment). Treatment did not affect total litter size; however, CONT sows gave birth to more live and fewer dead piglets compared with CAFF sows; 14.5±0.73 v. 11.7±1.03 and 0.7±0.20 v. 3.2±0.77; P<0.05). Mean, minimum and maximum piglet birthweight were unaffected by treatment. Compared with the control, caffeine increased the proportion of piglets with a birthweight <1 kg (0.16±0.05 v. 0.05±0.02; P=0.072) and decreased the proportion of live born piglets surviving to day 5 postpartum (0.77±0.06 v. 0.90±0.02; P<0.05) and to weaning (0.74±0.06 v. 0.90±0.02; P<0.05). Overall, the current data provided the first evidence that caffeine supplementation of sows receiving progesterone to prevent premature farrowing impaired piglet survival during, and shortly after parturition. This negative outcome may be linked to extended farrowing durations and an increase in the proportion of very light piglets at birth. These data provide compelling, albeit preliminary, evidence that caffeine and progesterone should not be used together at the end of gestation.     

Effects of l-carnitine in the distillers dried grains with solubles diet of sows on reproductive performance and antioxidant status of sows and their offspring

Distillers dried grains with solubles (DDGS) are highly susceptible to lipid oxidation because DDGS contain about 10% crude fat, which is largely composed of polyunsaturated fatty acids. l-carnitine serves an important function in fatty acids β-oxidation, and also has antioxidant properties. The objective of this study was to examine the effects of l-carnitine in the DDGS diet of gestating and lactating sows on reproductive performance, milk composition and antioxidant status of sows and their offspring. One hundred and twenty sows (Landrace×Large white, mean parity 4.2, initial BW 230 kg) were randomly allotted to 1 of 4 dietary treatments (n=30 sows/treatment). Treatments were arranged as a 2×2 factorial with two levels of dietary DDGS (0 v. 250 g/kg in gestating diets and 400 g/kg in lactating diets) and two levels of dietary l-carnitine (0 v. 100 mg/kg in gestating diets and 0 v. 200 mg/kg in lactating diets). Distillers dried grains with solubles had no significant effect on litter size but significantly reduced the birth weights and weaning weights of piglets (P<0.05). Distillers dried grains with solubles reduced the antioxidant enzyme activities (P<0.05) and increased the malondialdehyde level in the plasma of sows on day 60 of gestation (P=0.004) and day 14 of lactation (P=0.008). The compositions of colostrum and milk were not affected by inclusion of DDGS and dietary l-carnitine (P>0.05). Supplementing the diets with l-carnitine had no significant effect of total litter size (P>0.05) but increased the number of piglets born alive and piglets weaned, birth weight and weaning weight of piglets and litter weight at birth and weaning (P<0.05). l-carnitine supplementation also increased the concentration of l-carnitine in milk and l-carnitine status of piglets (P<0.05). The antioxidant enzyme activities of new born and weaning piglets were increased (P<0.05) by maternal dietary l-carnitine but this did not extend to finishing pigs. In conclusion, including DDGS in the sows diet could induce oxidative stress, which may be associated with the reduced individual birth and weaning weight of piglets. Dietary l-carnitine supplementation improved the antioxidant and l-carnitine status of sows, which may be associated with the improved reproduction and piglet performance and the antioxidant status of piglets at birth and weaning. There were no interactions between DDGS and l-carnitine.     

Effect of pre-weaning feeding regimens on post-weaning growth performance of Sahiwal calves

The objective of the study was to assess the post-weaning growth response of Sahiwal calves reared on four different pre-weaning dietary regimens. The four diets were: (a) whole cow's milk, starter ration (SR; CP = 20%, total digestible nutrients (TDN) = 72%) and Berseem hay (H; Egyptian clover; CP = 21%, TDN = 63%); (b) whole cow's milk + H; (c) milk replacer (MR; reconstituted to supplier specification; Sprayfo®) + SR + H; and (d) MR + H. The protein and fat percentages of reconstituted MR were 2.22 and 1.84, respectively. Milk or MR were fed at the rate of 10% of the calves’ body weight (BW) until 56 days of age, and then withdrawn gradually until weaned completely by 84 days of age. The average initial BW of calves in groups A, B, C and D were 56.3 ± 1.0, 47.5 ± 1.0, 40.4 ± 1.0 and 30.3 ± 1.0 kg, respectively. Initially, there were 12 calves in each group with six of each sex; however, one male calf died from each of groups B and C and were not replaced. During the post-weaning period, 13 to 24 weeks, the calves were fed a single total mixed ration ad libitum based on maize, canola meal, wheat straw and molasses containing 16% CP and 70% TDN. Daily feed intake and weekly BW gains were recorded. The data were analyzed by MIXED model analysis procedures using the statistical program SAS. The intake of calves as percent of their BW, feed conversion ratio and cost per kg of BW gain were not different (P > 0.05) across treatments. The daily gain at 24 weeks of age for the pre-weaning treatments A, B, C and D were 746 ± 33, 660 ± 33, 654 ± 33 and 527 ± 33 g/day and the final liveweights of calves were 119 ± 4.2, 102 ± 4.2, 95 ± 4.2 and 75 ± 4.2 kg, respectively. Gains were influenced significantly (P < 0.05) by pre-weaning treatments. The calves fed MR and H only during the pre-weaning period were unable to catch up post weaning with calves on other dietary treatments. The calves fed whole milk from birth at the rate of 10% of liveweight together with concentrates had higher weaning weight and superior growth rate post weaning as well. Thus, pre-weaning feeding was important for higher weaning weights and superior growth rates post weaning.     

Follicular development of sows at weaning in relation to estimated breeding value for within-litter variation in piglet birth weight

In this study we aimed to identify possible causes of within-litter variation in piglet birth weight (birth weight variation) by studying follicular development of sows at weaning in relation to their estimated breeding value (EBV) for birth weight variation. In total, 29 multiparous sows (parity 3 to 5) were selected on their EBV for birth weight variation (SD in grams; High-EBV: 15.8±1.6, N=14 and Low-EBV: −24.7±1.5, N=15). The two groups of sows had similar litter sizes (15.7 v. 16.9). Within 24 h after parturition, piglets were cross-fostered to ensure 13 suckling piglets per sow. Sows weaned 12.8±1.0 and 12.7±1.0 piglets, respectively, at days 26.1±0.2 of lactation. Blood and ovaries were collected within 2 h after weaning. The right ovary was immediately frozen to assess average follicle size and percentage healthy follicles of the 15 largest follicles. The left ovary was used to assess the percentage morphologically healthy cumulus-oocyte complexes (COCs) of the 15 largest follicles. To assess the metabolic state of the sows, body condition and the circulating metabolic markers insulin, IGF1, non-esterified fatty acid, creatinine, leptin, urea and fibroblast growth factor 21 were analysed at weaning. No significant differences were found in any of the measured follicular or metabolic parameters between High-EBV and Low-EBV. A higher weight loss during lactation was related to a lower percentage healthy COCs (β= −0.65, P=0.02). Serum creatinine, a marker for protein breakdown, was negatively related to average follicle size (β= −0.60, P=0.05). Backfat loss during lactation was related to a higher backfat thickness at parturition and to a higher average follicle size (β=0.36, P<0.001) at weaning. In conclusion, we hypothesise that modern hybrid sows with more backfat at the start of lactation are able to mobilise more energy from backfat during lactation and could thereby spare protein reserves to support follicular development.     

Increased dietary protein in the second trimester of gestation increases live weight gain and carcass composition in weaner calves to 6 months of age

Genetically similar nulliparous Polled Hereford heifers from a closed pedigree herd were used to evaluate the effects of dietary protein during the first and second trimester of gestation upon foetal, placental and postnatal growth. Heifers were randomly allocated into two groups at 35 days after artificial insemination (35 days post conception (dpc)) to a single bull and fed high (15.7% CP) or low (5.9% CP) protein in the first trimester (T1). At 90 dpc, half of each nutritional treatment group changed to a high- or low-protein diet for the second trimester until 180 dpc (T2). High protein intake in the second trimester increased birth weight in females (P=0.05), but there was no effect of treatment upon birth weight when taken over both sexes. Biparietal diameter was significantly increased by high protein in the second trimester with the effect being greater in the female (P=0.02), but also significant overall (P=0.05). Placental weight was positively correlated with birth weight, fibroblast volume and relative blood vessel volume (P<0.05). Placental fibroblast density was increased and trophoblast volume decreased in the high-protein first trimester treatment group (P<0.05). There was a trend for placental weight to be increased by high protein in the second trimester (P=0.06). Calves from heifers fed the high-protein treatment in the second trimester weighed significantly more on all occasions preweaning (at 1 month (P=0.0004), 2 months (P=0.006), 3 months (P=0.002), 4 months (P=0.01), 5 months (P=0.03), 6 months (P=0.001)), and grew at a faster rate over the 6-month period. By 6 months of age, the calves from heifers fed high nutrition in the second trimester weighed 33 kg heavier than those fed the low diet in the second trimester. These results suggest that dietary protein in early pregnancy alters the development of the bovine placenta and calf growth to weaning.