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 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.     

Effect of feed restriction or feeding high-fibre diet during the rearing period on body composition, serum parameters and productive performance of rabbit does

This study evaluated the effect of different feeding regimes from 11 weeks of age to first parturition on feed intake, leptin, non-esterified fatty acids (NEFA) and total protein serum levels, as well as productive performance in young rabbit does. In addition, body composition was estimated by bioimpedance analysis. Thirty-six 11-week-old does were randomly distributed in three groups. The AL-C group was fed ad libitum a control diet containing 350 g neutral detergent fibre (aNDFom)/kg, 11.6 MJ digestible energy (DE)/kg and 173 g crude protein (CP)/kg, and the does were inseminated at 16 weeks of age. The R-C group was fed 150 g/d of the same diet until 16 weeks of age, one week before artificial insemination (AI) at 17 weeks of age, and then fed ad libitum. The AL-F group was fed a diet containing 475 g aNDFom/kg, 9.4 MJ DE/kg and 174 g CP/kg ad libitum, and was inseminated at 17 weeks of age. During rearing (11-16 weeks), does in the R-C group had the lowest DE (1.54 MJ/d; P<0.003) and digestible protein (DP, 17.9 g/d; P<0.001) intake, as well as the lowest protein (172 g/kg; P<0.05) and energy (5.9 MJ/kg) body contents, leptin concentration at 16 weeks of age (2.48 ng/ml; P<0.001) and fertility (P<0.02) at first AI. Daily feed intake during pregnancy and lactation, as well as prolificacy and litter weight, were similar among groups. The highest percentage of body fat was observed for all the does when were inseminated for the first time (135 g/kg; P<0.001), consistent with the highest leptin (4.48 ng/ml; P<0.001) and total protein serum levels (6.87 g/dl; P<0.001) at this time. Serum NEFA level around parturition was higher (P<0.05) in groups AL-C and R-C (1.11 and 0.85 mmol/l) than in group AL-F (0.71 mmol/l), suggesting a lower lipid mobilization that tended to improve fertility rate for AL-F does on day 11 post-parturition (P<0.09). In conclusion, feed restriction during the rearing period delays reproductive development in young rabbits. In nulliparous does, ad libitum feeding during rearing with a high-fibre diet allows a similar productive performance to that of feeding with a less fibrous diet. Nevertheless, the use of high fibre diets during rearing does not affect feed intake throughout the first pregnancy and lactation.     

Effect of feeding program during rearing and age at first insemination on performances during subsequent reproduction in young rabbit does

An experiment was performed to study the effect of the feeding program and age at first mating on body growth, feed intake, reproductive performance, and culling of rabbit does over three parities, using 155 does of a strain of New Zealand white rabbits. Three treatments were applied. Ad libitum feeding until first insemination at 14.5 wk (AL-14.5) or 17.5 wk of age (AL-17.5), and restrictive feeding from five wk of age until first insemination at 17.5 wk of age (R-17.5). At first insemination, the BW of AL-14.5 and R-17.5 was similar (3 907 vs. 3 791 +/- 46 g, respectively), whereas AL-17.5 does were heavier (4 390 +/- 46 g, P < 0.001). During reproduction, performance of AL-17.5 was not improved compared to AL-14.5 and R-17.5 does. Al-17.5 does showed a lower feed intake during the first gestation (-25%) and first parity (-10%) than R- 17.5, resulting in weight loss (-6%) during the first gestation and decreased litter weights (-19%) and litter growth (-14%) in the first parity. Extended first mating by three wk (17.5 vs. 14.5 wk) but similar BW at first mating did not affect feed intake and BW development during the first three parities. However, the number of live born kits and weight at first kindling, and litter growth in the first parity were improved in R-17.5 (+23%, +18%, and +14%, respectively). Reproductive performance can be improved by restricted feeding during rearing and extended first insemination to 17.5 wk of age. However, the culling rate was not affected by the rearing strategy.     

Early deviations in performance,metabolic and immunological indicators affect stayability in rabbit females

The main purpose of this study was to find several early factors affecting stayability in rabbit females. To reach this goal, 203 females were used from their first artificial insemination to their sixth parturition. Throughout that period, 48 traits were recorded, considered to be performance, metabolic and immunological indicators. These traits were initially recorded in females’ first reproductive cycle. Later, removed females due to death or culling and those that were non-removed were identified. A first analysis was used to explore whether it was possible to classify females between those reaching and those not reaching up to the mean lifespan of a rabbit female (the fifth reproductive) cycle using information from the first reproductive cycle. The analysis results showed that 97% of the non-removed females were classified correctly, whereas only 60% of the removed females were classified as animals to be removed. The reason for this difference lies in the model’s characteristics, which was designed using early traits and was able to classify only the cases in which females would be removed due to performance, metabolic or immunologic imbalances in their early lives. Our results suggest that the model defines the necessary conditions, but not the sufficient ones, for females to remain alive in the herd. The aim of a second analysis was to find out the main early differences between the non-removed and removed females. The live weights records taken in the first cycle indicated that the females removed in their first cycle were lighter, while those removed in their second cycle were heavier with longer stayability (−203 and +202 g on average, respectively; P < 0.05). Non-removed females showed higher glucose and lower beta-hydroxybutyrate concentrations in the first cycle than the removed females (+4.8 and −10.7%, respectively; P < 0.05). The average lymphocytes B counts in the first cycle were 22.7% higher in the non-removed females group (P < 0.05). The females removed in the first reproductive cycle presented a higher granulocytes/lymphocytes ratio in this cycle than those that at least reached the second cycle (4.81 v. 1.66; P < 0.001). Consequently, non-removed females at sixth parturition offered adequate body development and energy levels, less immunological stress and a more mature immune function in the first reproductive cycle. The females that deviated from this pattern were at higher risk of being removed from the herd.     

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.     

Long-term implications of feed energy source in different genetic types of reproductive rabbit females: III. Fitness and productivity

The specialization process associated with genetic selection could be associated with functional disorders, affecting the reproductive success of females (fitness). We hypothesized that by modulating energy acquisition and allocation of females we could balance productivity and reproductive success. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66) maternal line specialized in prolificacy, LP (n=67) generalist maternal line, R (n=70) paternal line specialized in growth rate. We fed each genetic type with two diets specifically designed to promote milk yield (AF) or body reserves recovery (CS). We controlled females between their first and fifth reproductive cycles, recording traits related with productivity and fitness of females. H females fed CS had on average 11.2±0.43 kits with an individual weight of 54±1.2 g at birth and 525±11 g at weaning. Their conception rate when multiparous was 44% and their survival rate at the end of the experiment 30%. When they were fed AF, the individual weight of kits was 3.8 g heavier (P<0.05) at birth and 38 g heavier at weaning (P<0.05), the conception rate when multiparous increased 23 percentage points (P<0.05) and the survival rate at the end of the experiment 25 percentage points (P<0.05). LP females fed CS had on average 10.8±0.43 kits with an individual weight of 52±1.2 g at birth and 578±11 g at weaning. Their conception rate when multiparous was 79% and their survival rate at the end of the experiment 75%. When they were fed AF, it only increased individual weight of kits at weaning (+39 g; P<0.05). R females fed CS had on average 8.4±0.43 kits with an individual weight of 60±1.2 g at birth and 568±11 g at weaning. Their conception rate when multiparous was 60% and their survival rate at the end of the experiment 37%. When they were fed AF, they presented 1.4 kits less at birth (P<0.05) but heavier at birth (+4.9 g; P<0.05) and at weaning (+37 g; P<0.05). Therefore, we observed that genetic types prioritized different fitness components and that diets could affected them. In this sense, seems that more specialized genetic types, were more sensitive to diets than the more generalist type.     

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.     

Eicosapentaenoic acid- and docosahexaenoic acid-rich fish oil in sow and piglet diets modifies blood oxylipins and immune indicators in both,sows and suckling piglets

Over the last decades, genetic selection has increased sows’ litter size. Consequently, there is a high proportion of piglets born with low weight which are vulnerable. Their viability may potentially be enhanced through early nutrition. The aim of the current study was to evaluate whether including a fish oil rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the diets of the sow and piglets was able to increase concentrations of anti-inflammatory molecules in their blood. Thirty-six sows, in four consecutive batches, were randomly assigned to either a control diet with animal fat (15 g/kg in gestation and 30 g/kg in lactation) or an n-3 long-chain fatty acid (n-3 LCFA) diet from insemination until the end of lactation. From day 11 of lactation, piglets were also offered a diet containing 30 g/kg of animal fat or n-3 LCFA. To prepare the n-3 LCFA diet, 15 g/kg or 30 g/kg of animal fat in the control diet were replaced by an equivalent amount of solid fish oil for sows and piglets, respectively. All the sows were sampled for serum and plasma at day 108 of gestation and at weaning. Additionally, only for the first batch of sows, blood samples were also obtained at weaning from the two lightest (>800 g) and the two heaviest birth weight piglets in each litter. Serum fatty acids (FAs) were quantified by gas chromatography, plasma oxylipins by ultra-HPLC-MS and plasma immunoglobulins (Ig) and cytokines by ELISA. The n-3 LCFA diet increased the concentrations of n-3 FAs in gestating and lactating sows and in piglets (P < 0.001, P < 0.001 and P = 0.011, respectively), particularly EPA (P < 0.001, P < 0.001 and P < 0.001, respectively) and DHA (P < 0.001, P < 0.001 and P < 0.001, respectively), and also their oxygenated derivatives. In addition, fish oil increased plasma IgM in gestating and lactating sows (P = 0.014 and P = 0.008, respectively), interleukin (IL) 6 in sows at weaning (P = 0.012), and IL1β in piglets (P = 0.018). Birth BW of piglets, regardless of diet, slightly influenced some of the n-6-derived oxylipins. In conclusion, fish oil addition in diets increased the blood concentrations of n-3 FAs and their oxygenated derivatives, some of which have anti-inflammatory activity, in gestating and lactating sows and piglets, IgM in gestating and lactating sows, IL6 in lactating sows and IL1β in piglets.     

Milk production and composition,and progeny performance in young ewes with high merit for rapid growth and muscle and fat accumulation

In ewe lambs, acceleration of growth and accumulation of both muscle and fat leads to earlier sexual maturity and better reproductive performance. The next stage in the development of this theme is to test whether these aspects of growth in young ewes affect milk production in their first lactation and the growth of their first progeny. We studied 75 young Merino ewes that had known phenotypic values for depth of eye muscle (EMD) and fat (FAT), and known Australian Sheep Breeding Values for post-weaning weight (PWT) and depths of eye muscle (PEMD) and fat (PFAT). They lambed for the first time at 1 year of age. Their lambs were weighed weekly from birth to weaning at 10 weeks to determine live weight gain and weaning weight. Progeny birth weight was positively associated with live weight gain and weaning weight (P<0.001). The PWT of the mothers was positively associated with birth weight (P<0.01), live weight gain and weaning weight of the progeny (P<0.05); however, these progeny traits were not influenced by EMD, FAT, PEMD, PFAT of the mothers (P>0.05). The PWT of the sire was positively associated with live weight gain (P<0.05) and weaning weight of the progeny (P<0.01). At around day 20 postpartum, we measured milk production and milk composition (fat, protein, lactose, total solids). Milk production was influenced positively by birth type (single or twin; P<0.05) and negatively by birth weight (P<0.05), but not by mother phenotype or genotype, sire genotype of the mother or the sex of the progeny (P>0.05). The concentrations of fat, protein, lactose and total solids in the milk were not affected by the phenotype or genotype of the mothers or of the sires of the mothers, or by the sex of the progeny (P>0.05). We conclude that selection of young Merino ewes for better growth, and more rapid accumulation of muscle and fat, will lead to progeny that are heavier at birth, grow faster and are heavier at weaning. Moreover, milk production and composition do not seem to be affected by the genetic merit of the mother for post-weaning live weight or PEMD or PFAT. Therefore, Merino ewes can lamb at 1 year of age without affecting the production objectives of the Merino sheep industry.     

Correlated response in body condition and energy mobilisation in rabbits selected for litter size variability

A divergent selection experiment on litter size variability (high and low lines) was performed in rabbits over seven generations. The aim of this study was to evaluate the correlated responses to selection in body condition and fat reserves mobilisation. Litter size variability was estimated as phenotypic variance of litter size within female after correcting for the year-season and the parity-lactation status effects. A total of 226 females were used in this study, of which 158 females were used to measure body condition and energy mobilisation. Body condition was measured as BW and perirenal fat thickness. Females were stimulated with the adrenergic isoproterenol. Mobilisation capacity of fat reserves was measured by the lipolytic potential, defined as the increment in non-esterified fatty acids (NEFA) levels from basal concentration until adrenergic stimulation at mating, delivery and 10 days after delivery of the second reproductive cycle. Females were classified as survivor or non-survivor when they were culled for sanitary reasons or died before the third kindling. Data were analysed using Bayesian methodology. Survivor females presented higher BW than the non-survivor females at delivery (238 g, P=1.00) and 10 days after delivery (276 g, P=1.00). They also showed higher perirenal fat thickness at 10 days after delivery (0.62 mm, P=1.00). At delivery, basal NEFA levels was lower in survivor than non-survivor females (−0.18 mmol/l, P=1.00), but their lipolytic potential (∆NEFA) was higher (0.08 mmol/l, P=0.94). Body weight was similar between lines in survivor females. Perirenal fat thickness was lower in the high line than in the low line at delivery (−0.23 mm, P=0.90) and 10 days after delivery (−0.28 mm, P=0.92). The high line exhibited higher NEFA (0.10 mmol/l, P=0.93) and lower ∆NEFA (−0.08 mmol/l, P=0.92) than the low line at delivery. The low line showed a favourable correlated response to selection on body condition and fat reserves mobilisation. In conclusion, the low line selected for litter size variability seems to adapt better to adverse conditions, as it has a greater capacity to mobilise energy reserves at delivery than the high line. Females that adequately manage their body reserves and perform energy mobilisation correctly have a lower risk of dying or being culled.     

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.     

Reproductive performance of high growth rate gilts inseminated at an early age

The aim of this work was to determine if gilts, which have a high growth rate (GR) could be mated earlier without reducing the reproductive performance or increasing the culling rate up to the third parity. Gilts of Camborough 22 (C22, n=568) breeding were mated and allocated into three groups according to weight and age on the insemination day. G1 (n=164)-gilts with a GR>or=700 g/d and inseminated at <210 d. G2 (n=165)-gilts with a GR>or=700 g/d and inseminated at >or=210 d. G3 (n=239)-gilts with a GR<700 g/d and inseminated at >or=210 d. All females were fed ad libitum from 150 d on and were inseminated at their second estrus or later. The minimum weight at mating was 127 kg. Three parities were studied, with farrowing rate, litter size and culling rate being compared. At the first parity, G2 gilts produced, on average, one more piglet than the other groups (P<0.05). However, when analyzing three parities, there were no differences in total born (11.6 x 12.3 x 11.7), farrowing rate (87.1% x 88.7% x 89.8%) and culling rate (30.2% x 25.3% x 28.2%) among G1-G3 groups, respectively (P>0.05). In conclusion, gilts, which had a minimum weight of 127 kg can be inseminated at their second or greater estrus, between 185 and <210 d of age, without impairing their productive performance over three parities.     

How does barley supplementation in lambs grazing alfalfa affect meat sensory quality and authentication?

Excessive flavour in lamb meat is undesirable for consumers and can prompt purchase resistance. Volatile indoles responsible for off-flavours accumulate more in the fat of lambs on pasture than on grain and are enhanced when lambs graze alfalfa. Here, we investigated whether barley supplementation of lambs grazing alfalfa influences meat sensory quality. Using three groups of 12 male Romane lambs, we compared three feeding regimes: alfalfa grazing (AG), alfalfa grazing + daily supplementation with barley (29 g/kg live weight^0.75, AGS) and stall feeding with concentrate and hay (SF). As some of the compounds involved in meat sensory traits may act as dietary biomarkers, we also investigated potential implications for meat authentication. Although barley represented 38% of the diet in AGS lambs, it did not offer any advantage for animal average daily gain or parasitism level. Animal performance, carcass weight and fatness did not differ between feeding regimes. Dorsal fat firmness tended to be greater in AG than AGS and greater in AGS than SF. Skatole and indole concentrations in perirenal and dorsal fat were lower in SF lambs than in AG and AGS lambs (P<0.01 to P<0.0001), but did not differ between AG and AGS lambs. Yellowness, chroma and hue angle of perirenal fat were lower in SF lambs than in AG and AGS lambs (P<0.001), but did not differ between AG and AGS lambs. Absolute value of the mean integral for both perirenal fat and subcutaneous caudal fat (AVMI_PF and AVMI_SC), quantifying the intensity of light absorption by carotenoids in perirenal and subcutaneous caudal fat, respectively, were lower in SF lambs than in AG and AGS lambs (P<0.0001 for both comparisons), but did not differ between AG and AGS lambs. Meat colour was unaffected by the treatment. We confirm that lambs grazing alfalfa accumulate high levels of volatile indoles in their fat, but we show that barley supplementation to lambs grazing alfalfa is not effective in reducing fat volatile indoles concentration and excessive odour/flavour in the meat. We also confirm that both perirenal fat skatole concentration and AVMI_PF are of interest for discriminating lambs that grazed alfalfa from lambs that were stall-fed, and we show that they are not effective for discriminating supplemented from non-supplemented grazing lambs.     

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.     

Impact of fibre intake and fibre source on digestibility,gut development,retention time and growth performance of indigenous and exotic pigs

The impact of fibre level and fibre source on digestibility, gastrointestinal tract (GIT) development, total tract mean retention time (MRT) and growth performance was studied in indigenous Mong Cai (MC) and exotic Landrace × Yorkshire (LY) pigs. The diets were based on maize, rice bran, soyabean meal, fish meal and soyabean oil, and cassava residue (CR) or brewer's grain (BG) as fibrous ingredient sources in the high-fibre diets (HF) and were fed ad libitum. A low-fibre diet (LF), containing around 200 g NDF/kg dry matter (DM), was formulated without CR and BG as feed ingredients. The HF diets (HF-CR and HF-BG) were formulated to contain around 270 g NDF/kg DM. The experiment was arranged as a 2 × 3 factorial completely randomized design with six replications, and lasted 27 days. Increased dietary fibre level resulted in a reduction (P < 0.05) in average daily gain, digestibility of organic matter (OM), CP and gross energy (GE) at the ileum and in the total tract, and in MRT, and an increase (P < 0.05) in the feed conversion ratio and in the weight of the GIT (except for small intestine and caecum). The coefficients of total tract digestibility of fibre fractions were higher in HF diets than in the LF diet, with highest values for diet HF-CR, which had a high proportion of soluble non-starch polysaccharides. MC pigs had longer MRT of digesta than LY pigs (P < 0.05), resulting in higher digestibility at the ileum and in the total tract. Across diets and breeds, the total tract apparent digestibility of OM, CP and GE was positively related (R² = 0.80 to 0.84) to the MRT of solids, whereas the MRT was negatively related to the DM intake (R² = 0.60).     

Culling intervals and culling risks in four stages of the reproductive life of first service and reserviced female pigs in commercial herds

The objectives of this study were to measure culling intervals and culling risks in the four stages of the reproductive life of female pigs and to compare culling intervals between the number of services and between herd groups, based on herd productivity. We also compared survival patterns of females pigs between these herd groups. Our data set included lifetime records of 52,792 females born between 2001 and 2004 in 101 commercial herds. Two herd groups were selected on the basis of the upper 25th percentile of pigs weaned per mated female per 5 yr between 2002 and 2006, namely the high-performing herds, and ordinary herds. Culled females were also allocated into four groups based on the stages of their reproductive life when culled: unmated gilts, mated gilts, unmated sows, and mated sows. Culling intervals in unmated gilts and mated gilts were defined as the number of days from birth to culling and from first mating to culling, respectively. Culling intervals in unmated sows and mated sows were the number of days from weaning to culling. The number of services was categorized into two groups: first service and reservice groups. Multilevel linear mixed-effects models and survival analysis were performed. Culling intervals (±SEM) in unmated gilts, mated gilts, unmated sows, and mated sows were 302.9 ± 1.16, 98.4 ± 0.92, 14.3 ± 0.12, and 89.6 ± 0.42 d, respectively. Culling risks in the four groups were 5.6%, 7.1%, 58.0%, and 29.3%, respectively. In unmated gilts, mated gilts, and mated sows, the culling intervals in the high-performing herds were 43.0, 18.9, and 16.0 d shorter than those in ordinary herds, respectively (P < 0.05), but no difference was found between the herd groups for the culling interval of unmated sows. For mated sows in the reservice group, culling intervals of high-performing herds were ≥13.7 d shorter than those of the ordinary herds (P < 0.05), but for mated sows in the first service group, there was no difference in the culling interval between the herd groups. The culling hazard from 8 wk postweaning for mated sows in high-performing herds increased more rapidly than that in ordinary herds. In conclusion, to reduce culling intervals and improve herd productivity, we recommend implementing a strict culling policy for mated gilts and mated sows, especially reserviced females.     

The potential interaction between body condition score at calving and dietary starch content on productive and reproductive performance of early-lactating dairy cows

Improving reproductive performance is one of the most important factors affecting the profitability of dairy herds. This study investigated the effect of feeding a high starch (HS) diet and body condition score (BCS) at calving on blood metabolites, fertility and ovarian function and milk production in Holstein dairy cows. One hundred seventy-four multiparous cows were fed common close-up and early lactation diets during the first 15 days in milk (DIM). Cows were randomly assigned to 1 of 2 experimental diets from 16 until 50 DIM (n = 87 per group); normal starch (228 g/kg diet DM; NS) or HS (270 g/kg diet DM; HS) diets. Each treatment group was further subdivided based on BCS at calving as normal BCS (BCS ⩽ 3.5; normal BCS (NBCS); n = 45) or high BCS (HBCS) (BCS ⩾ 3.75; HBCS; n = 42). A significant difference was detected for increased milk production (47.24 v. 44.55 kg/day) and decreased milk fat (33.93 v. 36.33 g/kg) in cows fed HS or NS, respectively. Plasma glucose and insulin concentrations were significantly higher in cows fed the HS compared to the NS diet. Diets significantly affected DIM at first artificial insemination (AI, 79.51 ± 3.83 v. 90.40 ± 3.83 days for cows fed HS and NS diets, respectively). High BCS groups had greater milk fat content and elevated plasma nonesterified fatty acids (NEFA), β hydroxybutyrate (BHB) and bilirubin concentrations. In general, feeding higher starch diets to normal BCS cows during the first 50 DIM improved productive and reproductive performance of early-lactating dairy cows.     

Effects of konjac flour inclusion in gestation diets on the nutrient digestibility,lactation feed intake and reproductive performance of sows

This study was conducted to investigate the effects of konjac flour (KF) inclusion in gestation diets of sows on nutrients digestibility, lactation feed intake, reproductive performance of sows and preweaning performance of piglets. Two isoenergetic and isonitrogenous gestation diets were formulated: a control diet and a 2.1% KF-supplemented diet (KF diet). Both diets had the same NDF and insoluble fiber (ISF) levels, but the KF diet had higher soluble fiber (SF) level. The day after breeding, 96 multiparous sows were assigned to the two dietary treatments. Restrict-fed during gestation, in contrast, all sows were offered the same lactation diet ad libitum. Response criteria included sow BW, backfat depth, lactation feed intake, weaning-to-estrus interval, litter size and piglet’s weight at parturition and day 21 of lactation. On day 60 of gestation, 20 sows were used to measure nutrient digestibility. Results showed that the digestibility of dry matter, gross energy, crude fiber and ADF were not affected by the dietary treatments. The inclusion of KF in gestation diets increased NDF digestibility (P<0.05) and tended to increase the digestibility of CP (P=0.05) compared with the control diet group. In addition, dietary treatment during gestation did not affect litter size, BW and backfat gain during gestation, lactation weight, backfat loss or weaning-to-estrus interval of sows. However, sows fed the KF diet consumed more (P<0.05) lactation diet per day than sows in the control group. Accordingly, sows fed the KF diet showed greater average piglet weights on day 21 of lactation (P=0.09), and the litter weight of sows fed the KF diet on day 21 of lactation increased by 3.95 kg compared with sows fed the control diet (not significant). In conclusion, the inclusion of KF in gestation diets increased lactation feed intake of sows and tended to improve litter performance.     

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.