Comparison of growth performance and agonistic interaction in weaned piglets of different weight classes from farrowing systems with group or single housing

The present study was designed to analyze the growth performance, behavioral patterns and intensity of injuries of weaned pigs (26 days) during a rearing period of 6 weeks. The farrowing system (group housing (GH) v. single housing (SH)) and the post-weaning regrouping weight class (light, medium, heavy) were considered as the main factors. A number of 120 GH-pigs and 120 SH-pigs were kept in three batches (20 pens, 12 pigs each). The GH- and SH-pigs were divided by weight into three groups: light (5 to ⩽7 kg), medium (>7 to ⩽9 kg) and heavy (>9 to ⩽12 kg), with two pigs of six different litters in each pen. The pigs were weighed individually at weaning (week 1) and during rearing (weeks 2, 3 and 7). The feed conversion ratio (FCR) was calculated between weeks 1 and 7. The duration and number of fights (NF) per pen and hour were determined by continuous sampling (40 h after weaning). Lesions of the integument were scored into four classes (none, minor, medium, severe) and recorded at weaning and 48 h afterwards. The farrowing system had no effect on the weights in week 1 (GH: 7.8 kg v. SH: 7.7 kg; week as linear, quadratic regression nested within housing systems) or in week 7 (GH: 29.4 kg v. SH: 28.6 kg). The body weights were influenced significantly by the weaning weight class (light: 11.7 kg (s.e.m.: 0.30), medium: 14.8 kg (s.e.m.: 0.22), heavy: 17.3 kg (s.e.m.: 0.26)). The FCR of the GH-pigs was 1.64 (s.e.m.: 0.03) and 1.58 (s.e.m.: 0.03) for SH-pigs. A reduced agonistic behavior of the GH-pigs was observed with 2.1 fights per pen and hour (s.e.m.: 0.07) v. the SH-pigs with 4.6 fights per pen and hour (s.e.m.: 0.05). The fight duration of the GH-pigs with 10.3 s per pen and hour (s.e.m.: 1.07) was significantly lower in comparison to the SH-pigs with 18.8 s per pen and hour (s.e.m.: 1.06). The SH-pigs had more new skin lesions at the shoulders than the GH-pigs 48 h after weaning (P < 0.05). In conclusion, early mixing of unacquainted litters during lactation had no influence on their growth performance during rearing but reduced agonistic behavior and lesion score difference during the first 2 days after weaning. No significant interaction between the farrowing system and weaning weight class was detected with regard to growth performance and NF.     

The effect of level of feeding in early gestation on reproductive success in young rabbit does

An experiment examined the effect of restricted feeding during early gestation on later feed intake and on kindling performance in young rabbit does. Nulliparous rabbit does (n=94) were inseminated at 14.5 weeks of age. During the first 10 days of gestation, does were fed individually either to appetite (AL) or 1.35 times maintenance requirement (R). After 10 days of gestation, all animals were fed to appetite. Does were weighed at insemination and after kindling. Feed intake was recorded during the first 10 days of gestation and weekly, thereafter. The number of does that kindled, number of live and stillborn kits and litter weight was recorded. The experiment ended after kindling. During feed restriction, AL does consumed 70 g/day more on an average than R does (209 and 139+/-4 g for AL and R, respectively; P<0.001). In the first and second week after feed restriction, compensatory feed intake occurred. Restrictive fed does ate more than AL does (+34+/-5 g/day from days 11 to 17 of gestation; P<0.001; +17+/-6g/day from days 18 to 24 of gestation; P<0.05). In the last week of gestation, feed intake of AL and R was comparable (89 and 100+/-5 g, respectively). At kindling, AL does had consumed 8+/-3g/day more feed over the total gestation period than R does (P<0.04). Feeding level during early gestation neither affected the kindling rate (83%), total litter size (7.9+/-0.4) nor the number of does with stillborn kits (10 versus 9 for AL and R, respectively). Regardless of treatment, in the last week of gestation (days 25-32) the number of does with stillbirth was lower and average birth weight was higher (P<0.01) in does eating more than the average daily feed intake compared to does eating below average. Based on the results of this study it was concluded that feed restriction for 10 days in early gestation does not affect kindling performance of young does, but feed intake in the last week of gestation affects kit survival and birth weight.     

Reproductive performance of multiparous rabbit lactating does: effect of lighting programs and PMSG use

This study aims to determine if Pregnant Mare Serum Gonadotrophin (PMSG), used for oestrous synchronization in multiparous lactating does, could be replaced by one of the following lighting schedules without impairing reproductive performance: (a) 12-h L (light)/12-h D (dark) or (b) 8-h L/16-h D, until day 6 before artificial insemination (AI), when in both cases photoperiod was changed to 16-h L/8-h D and maintained until the day of AI, and in the following 4 days post Al the light hours were progressively reduced to the initial schedules. Two groups of 20 does each were respectively submitted to one of the lighting schedules specified above. All does were artificially inseminated in 6 consecutive cycles at 42 days intervals. In the first, third and fifth AIs, PMSG (20 IU/doe via sc 48 h before AI) was used in the two groups of does, whereas in the second, fourth and sixth Als no hormonal treatment was used. Degree of oestrous synchronization (also referred in text as sexual receptivity) was estimated by the colour of the vulva at AI. Reproductive performance of does was evaluated based on fertility (kindling rates), prolificity, mortality at birth, mortality at 21 days post birth, weight of the litter at 21 days post birth and number of weaned rabbits. Oestrous was better synchronized when PMSG was used with any of the two lighting programs. Without using PMSG, a photoperiod of 12-h L/12-h D until 6 days before AI resulted in a better sexual receptivity of does than 8-h L/16-h D. Fertility, prolificity, mortality of young rabbits at 21 days, the weight of the litters at 21 days and the number of weaned rabbits did not vary with the lighting program and were not affected by the PMSG treatment. Mortality at birth, however, was higher (+1 dead kit per litter) in litters housed under a light program of 12-h L/12-h D. Global productivity (number of weaned rabbits per 100 inseminated does) was better when using PMSG, for both lighting schedules. When using a photoperiod of 12-h L/12-h D until 6 days before AI, and omitting the PMSG treatment, global productivity was scarcely reduced, however, it was considerably impaired when using a photoperiod of 8-h L/16-h D until 6 days before AI and no PMSG treatment.     

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 early contact between non-littermate piglets and of the complexity of farrowing conditions on social behaviour and weight gain

In this study we tested if contact possibilities between non-littermate piglets and complexity of farrowing conditions affect the pre- and post-weaning behaviour, weight gain and skin lesions of piglets. Suckling sows were either kept in a group housing system (GH), in a single pen loose housing system (LH), or in conventional farrowing crates (FC). In the single pen systems a piglet door to the adjacent pen was opened on d 10 after farrowing in half of the pens so that piglets were able to enter the neighbouring pen (LH+ and FC+). For control, in the other half of single pens no piglet doors were opened (LH− and FC−). In the group housing system piglets also were allowed to freely move within the whole system on d 10 after farrowing. After weaning on d 28 piglets were kept in littered rearing pens in an open stable holding 20 piglets each. Piglets from contact pens were mixed with those they previously had contact to whereas piglets from control pens were mixed with unfamiliar litters. Data were obtained from 230 litters (113 sows with 1935 farrowed piglets). All piglets were scored for skin lesions immediately before and 4 days after opening the piglet doors, as well as immediately before and 4 days after moving into rearing pens. Behaviour (biting, fighting, drinking and laying) of piglets was recorded in the rearing pens in a 48-h period after weaning for 2 × 4 h. Treatments did not affect the level of skin lesions in the rearing period (H = 8.72, df 4, ns) nor daily weight gain until weaning (F_4,216 = 1.21, ns). In the 48 h after moving to rearing pens, less intensive agonistic behaviour (fighting and biting) was observed in contact piglets (H = 53.36, df 4, P < 0.0001). Four days after weaning control piglets showed significantly higher numbers and more severe skin lesions than contact piglets and, in addition, lesion scores of piglets from the larger single farrowing pens with straw bedding were significantly lower compared to the single farrowing crate (H = 33.86, df 4, P < 0.0001). The latency for lying in the new rearing pen was decreasing (F_4,93 = 25.76, P < 0.001) and the latency for drinking (F_4,81 = 3.43, P = 0.01) was increasing with decreasing complexity and space allotment of the housing system but were not related to whether the piglets have had contact to other litters before weaning. Five weeks after weaning weight gain (F_4,204 = 7.01, P < 0.0001) and BW (F_4,207 = 5.34, P < 0.001) were higher in treatments offering contact. Our results show that familiarising piglets from different litters 10 day post partum by establishing contact possibilities through a piglet door reduces social stress at weaning and increases weight gain after weaning. Farrowing pens with straw bedding and enlarged space as offered in the farrowing pens and the group housing system can further decrease the level of harmful agonistic interactions after mixing unacquainted litters at weaning and can improve the adaptation of piglets towards the new environment of the rearing pen.     

Comparison of performance and welfare of single-caged and group-housed rabbit does

Although rabbit does are generally single housed on rabbit farms worldwide, it has been suggested by some specialists and recommendation of organic rabbit production systems that group housing of does is more comfortable and similar to the living conditions of the European wild rabbits. The aim of this experiment was to compare production of single-caged (S) and group-housed does (G). The S does were housed in commercial rabbit cages (floor area 0.32 m² and 0.3 m high). In treatment G, four does and one buck were housed in four pens measuring 7.7 m² (half of the floor was deep litter and the other half was plastic slat), with four nest boxes in each pen (n = 16). In treatment S, approximately half of the does (n = 18) were inseminated 2 days after kindling (S-33), whereas in the remaining does (n = 16) AI was done 11 days after kindling (S-42). A single-batch system (all of the does in the group were inseminated on the same day) was used in both S treatments. Kindling rates were 77.6%, 85.2% and 45.6% in treatments S-33, S-42 and G, respectively (P < 0.05). During the experiment, the percentage of does that kindled 0, 1, 2, 3, 4 and 5 times were 17%, 25%, 17%, 25%, 17% and 0% (G); 0%, 0%, 0%, 8%, 69% and 23% (S-33); and 0%, 0%, 17%, 58% and 25% (S-42, in this treatment does had a maximum of four kindlings). There were no significant differences among treatments for litter size. In treatments S-33, S-42 and G, suckling mortality was 14.0%, 15.2% and 38.5%, respectively (P < 0.001); survival of does was 71%, 81% and 50% (P = 0.084); and faecal corticosterone concentrations were 61, 54 and 175 nmol/g (P < 0.001). The high mortality of kits was associated with stress and aggressive behaviour of does, including scratching, biting or killing the kits, which resulted in the high rates of mortality and culling, as well as shorter lifespan of does. Because of high stress, increased mortality and morbidity, and low productivity, group housing of rabbit does resulted in poorer animal welfare and increased production costs, and therefore is not recommended.     

Naloxone and the kindling of seizures.

In view of evidence indicating that endogenous opiate-like peptides have epileptiform effects, we examined the effect of the opiate antagonist naloxone on the kindling of seizures produced by repeated electrical stimulation of the amygdala or the caudate nucleus in rats. Naloxone had no effect on the threshold for local after-discharge in the two areas and failed to retard the rate of kindling of clinical seizures. These results suggest that an interaction of opiate-like peptides with central opiate receptors does not play any critical role in the kindling of seizures.     

Field fertility with exported boar semen frozen in the new flatpack container

The present study tested the field fertility of frozen-thawed (FT) Swedish boar semen packaged in flat plastic containers (FlatPacks) and exported for artificial insemination (AI) to overseas nucleus herds. Semen from 47 Swedish boars of Landrace (L), Yorkshire (Y), and Hampshire (H) breeds was frozen using a lactose-egg yolk-based extender with 3% glycerol and 10(9) spermatozoa/ml in 5 ml FlatPacks. For all breeds, FT sperm membrane intactness averaged 60%, while mean FT sperm motility ranged from 49 to 53%. A total of 308 litters resulted from 421 overseas inseminations with FT semen, with a mean farrowing rate (FR) of 73% and 10.7 mean number total piglets born. In a within-sow analysis for the purebred L and Y breedings, the FR and litter size of FT semen were compared with natural matings (NM) and on-farm AI with liquid semen (NW/AI breedings) at the same farms. Farrowing rate was 72.3 and 78.8% (P = 0.23), total piglets 11.3 and 11.6 (P = 0.44), and live piglets 10.1 and 10.2 (P = 0.77), for the FT semen and NM/AI breedings, respectively. The present results suggest that this freezing protocol and FlatPack container maintains high sperm viability post-thaw. Further the fertility levels when inseminated at overseas nucleus herds seem to be similar to those achieved with (NM/AI breedings) at the same farms. This freezing method may be a reliable alternative for the freezing/thawing of boar semen under commercial AI conditions.     

Short communication: insoluble fibres in supplemental pre-weaning diets affect behaviour of suckling piglets

We investigated the effect of offering supplementary dietary fibres to suckling piglets on their behaviour and performance before weaning. From 5 to 22 days of age, suckling piglets were offered a high-fibre diet (HF; 5% cellulose; n=5 litters), or a control low-fibre diet (n=5 litters). Piglets were housed with the sows in individual farrowing pens, and had access to maternal milk until weaning, at 23 days of age. Behaviours of six focal piglets per pen were scored at 6, 16 and 21 days of age. All piglets were individually weighed at 5, 15 and 20 days of age and feed intake was measured daily at the pen level. Piglets on the HF diet were more active than controls (P=0.05), and spent more time suckling or massaging the udder (P=0.01) and interacting with pen mates (P=0.008). Time spent manipulating pen mates, which may reflect re-directed foraging activity in the absence of substrate, accounted for most of the time spent interacting with pen mates (⩾73% of total time spent interacting). Dietary fibres had no effect on BW and feed intake. In conclusion, inclusion of cellulose in the supplemental diet of suckling piglets affects behaviour, with no deleterious effects on performance before weaning.     

Long term effect of post-weaning rhythm on the body fat and performance of rabbit doe

Reproductive protocols based on standard (Control: 11 days post-partum) or extended rhythm (PW: post-weaning at 27 days post-partum) were compared. Two groups of fifty 19-week-old New Zealand White females were inseminated for seven consecutive cycles. The kits were weaned at 26 days. On the day of AI, all the does were submitted to ultrasound scanning of the perirenal regions to measure fat thickness. The fertility rate and several indexes of efficiency were calculated. Fat thickness, estimated perirenal fat and live weight were higher in PW does. The does submitted to post-weaning rhythm had a higher sexual receptivity (P < 0.01), and fertility rate (P < 0.01) whereas litter size and pre-weaning mortality were not affected. Primiparous Control does showed a particularly low fertility rate; the value increased successively but was always lower than in PW does. PW rhythm in comparison with the standard one seemed more adapted to doe reproductive physiology even if there was a lower production (35.0 vs. 38.8 rabbit sold/year) and risk of fatness (18% of multiparous does).     

Resynchronization with unknown pregnancy status using progestin-based timed artificial insemination protocol in beef cattle

Two experiments were designed to evaluate the use of resynchronization (RESYNCH) protocols using a progestin-based timed artificial insemination (TAI) protocol in beef cattle. In experiment 1, 475 cyclic Nelore heifers were resynchronized 22 days after the first TAI using two different inducers of new follicular wave emergence (estradiol benzoate [EB; n = 241] or GnRH [n = 234]) with the insertion of a norgestomet ear implant. At ear implant removal (7 days later), a pregnancy test was performed, and nonpregnant heifers received a dose of prostaglandin plus 0.5 mg of estradiol cypionate, with a timed insemination 48 hours later. The pregnancy rate after the first TAI was similar (P = 0.97) between treatments (EB [41.9%] vs. GnRH [41.5%]). However, EB-treated heifers (49.3%) had a greater (P = 0.04) pregnancy per AI (P/AI) after the resynchronization than the GnRH-treated heifers (37.2%). In experiment 2, the pregnancy loss in 664 zebu females (344 nonlactating cows and 320 cyclic heifers) between 30 and 60 days after resynchronization was evaluated. Females were randomly assigned to one of two groups (RESYNCH 22 days after the first TAI [n = 317] or submitted only to natural mating [NM; n = 347]). Females from the NM group were maintained with bulls from 15 to 30 days after the first TAI. The RESYNC-treated females were resynchronized 22 days after the first TAI using 1 mg of EB on the first day of the resynchronization, similar to experiment 1. No difference was found in P/AI (NM [57.1%] vs. RESYNC [61.5%]; P = 0.32) or pregnancy loss (NM [2.0%] vs. RESYNC [4.1%]; P = 0.21) after the first TAI. Moreover, the overall P/AI after the RESYNCH protocol was 47.5%. Thus, the administration of 1 mg of EB on day 22 after the first TAI, when the pregnancy status was undetermined, promotes a higher P/AI in the resynchronized TAI than the use of GnRH. Also, the administration of 1 mg of EB 22 days after the TAI did not affect the preestablished pregnancy.     

Reproductive performance of synchronized beef cows as affected by inhibition of suckling with nose tags or temporary calf removal

A study was conducted to determine whether presence of the calf during suckling inhibition influences the response to estrus synchronization in beef cows. Angus or Hereford cows (n=89) were administered Syncro-Mate-B (SMB), which consisted of a 6-mg norgestomet ear implant (in situ 9 d) in conjunction with 5 mg of estradiol valerate and 3 mg (im) of norgestomet. Cows were allotted by breed, body condition, stage of the estrous cycle, parity and date of parturition to 1 of 3 treatments: 48-h calf removal; ad libitum suckling; or inhibition of suckling with a nose tag for 48 h. Calves were weighed at time of SMB implant removal, 48 h later and at weaning. Cows were mated via AI approximately 12 h after detection of estrus during a 30-d period after implant removal followed by a natural service period of 35 d. At 48 h after implant removal, calf removal and nose tag calves had lost an average of 3.6 and 0.9 kg, respectively, while the suckled calves gained 1.8 kg (P < 0.01). Mean calf weight at weaning did not differ among treatments. Synchronized estrous response (within 5 d of implant removal) was not different among treatments. Pregnancy rate for cows exhibiting a synchronized estrus (5 d AI) for calf removal, nose tag and suckled cows was 76, 48 and 48%, respectively (P>0.10). Treatment did not affect the 30-d AI or overall 65-d pregnancy rate. In this study, there were no differences observed in the percentage of synchronized or pregnant cows following suckling inhibition by either a nose tag or calf removal. Transient reductions of calf body weight during the 48-h calf removal period did occur in both the nose tag and calf removal groups.     

Influence of supplemental dietary sprouted wheat on reproduction in artificially inseminated doe rabbits

The sprouted wheat contains great amounts of 6-methoxybenzoxazolinone (6-MBOA) a phenol compound that stimulates reproduction in certain small wild herbivorous mammals. The objective of the present study was to evaluate the effect of dietary sprouted wheat as supplement on reproduction in artificially inseminated doe rabbits. Two-month-old New Zealand White doe rabbits (n = 48) were randomly allocated to one of two treatments: (1) pelleted diet plus sprouted wheat for 6 consecutive days prior to service, (2) pelleted diet only (control). First insemination occurred when does reach 3200g body weight and bred 6 days after parturition across 6 months period during summer and autumn. Records from 41 does completing the experiment accounted for 192 inseminations and 142 kindlings equivalent to 4.6 +/- 0.15 and 3.5 +/- 0.15 litters per doe, respectively. Mean daily intake of sprouted wheat on wet and dry matter bases were 196.1 +/- 7.5 and 75.4 +/- 2.9g, respectively. The number of young born produced per doe during the trail was significantly (P = 0.02) greater in does fed sprouted wheat (28.1 +/- 1.2 versus 23.6 +/ -1.3 control). Does fed sprouted wheat had 0.65 +/- 0.06 receptivity rate at AI over 28 per cent greater (P = 0.001) than does in the control treatment. Sexual receptivity was not influenced by physiological status of does and season (P > 0.05). Diet and season had no effect (P>0.05) on kindling rate. However, physiological status had an effect (P = 0.002) on this variable. Kindling rates for nulliparous, lactating and non-lactating does were 0.95 +/- 0.08, 0.63 +/- 0.04 and 0.78 +/ -0.11, respectively. Sexually receptive does had a greater (P = 0.0001) kindling rate (0.95 +/- 0.05) than non-receptive females (0.63 +/-0.05). Does fed sprouted wheat produced larger (P = 0.02) litters than those in the control group: 7.7 +/- 0.30 and 6.8 +/- 0.32, respectively. There was an effect of season (P = 0.04) on the size of the litter at birth. Largest litters were born during autumn (7.9 +/- 0.37) than during summer (6.6 +/- 0.41). Receptive does had more (P = 0.002) young in the litter (7.9 +/- 0.28) than non-receptive (6.6 +/- 0.35). Feeding sprouted wheat as a source of biological 6-MBOA enhanced sexual receptivity and prolificacy in artificially inseminated doe rabbits bred in summer and autumn.     

The behaviour and welfare of sows and piglets in farrowing crates or lactation pens

Temporary confinement during parturition and early postpartum may provide an intermediary step preceding loose housing that offers improvement in sow and piglet welfare. Three experiments were conducted to investigate the implications of replacing farrowing crates (FCs) with an alternative housing system from 3 days postpartum until weaning. In each experiment sows farrowed in FCs and were randomly allocated at day 3 of lactation to either a FC or a pen with increased floor space (lactation pen (LP)) until weaning. In experiment 1, piglet growth and sow and piglet skin injuries were recorded for 32 sows and 128 focal piglets in these litters. Behaviour around nursing and piglet behavioural time budgets were also recorded for 24 of these litters (96 focal piglets for time budgets). In experiment 2, measures of skin injury and behavioural time budgets were conducted on 28 sows and 112 focal piglets. The behavioural response of sows to piglet vocalisation (maternal responsiveness test (MRT)) was also assessed. In experiment 3, piglet mortality from day 3 of lactation until weaning was recorded in 672 litters over 12 months. While housing did not affect piglet weight gain in experiment 1, or piglet skin injuries in experiments 1 or 2, sows in both experiments sustained more injuries in LP than FC (experiment 1, 2.9 v. 1.4; experiment 2, 2.5 v. 0.8 lesions/sow; P<0.05). Sow–piglet interactions were more frequent in LP than FC at days 11 and 18 postpartum in both experiment 1 (day 11, 1.4% v. 1.2%; day 18, 1.7% v. 1.0% of observations; P=0.05) and 2 (day 11, 1.0% v. 0.3%; and at day 18 were 1.0% v. 0.6% of observations; P<0.01), and LP sows were more responsive in the MRT in experiment 2 (2 v. 0 median number of tests in which sows react, P<0.01). In experiment 1 piglets played more (0.7% v. 0.3% of observations, P=0.05) and manipulated others less (0.3% v. 0.7% of observations, P=0.04) in LP, but more piglets missed nursing bouts (0.2 v. 0.1 piglets/bout, P<0.01) compared with FC. There was no effect of housing on piglet mortality from day 3 of lactation until weaning in experiment 3 (0.63 and 0.64 deaths/litter for LP and FC, respectively, P>0.05). Thus, housing sows and litters in LP from day 3 of lactation minimises piglet mortality while improving maternal behaviour in sows and social behaviour in piglets.     

Effect of different number of frozen spermatozoa inseminated on the reproductive performance of rabbit does

The relationship between the number of frozen spermatozoa inseminated and fertility rate and litter size at birth in rabbit does was investigated. Six hundred artificial inseminations (AI) were performed on multiparous lactating does with three spermatozoa concentrations: 10, 25, 50x10(6)spermatozoa/AI. All the does were synchronized with 20 UI of eCG 2 days before AI. The estimated sexual receptivity was 87%. The freezing-thawing procedure strongly reduced kinetic and functional traits (acrosome integrity, capacitation) of the spermatozoa. The number of spermatozoa inseminated did not affect the reproductive performance: the mean fertility rate and litter size values were 51.5% and 7.6%, respectively. Sexually receptive does (n=522) inseminated with frozen spermatozoa showed a 58.0% fertility rate whereas, non-receptive does (n=78), had a very poor fertility rate (7.8%).     

Sheep breeding schemes utilising artificial insemination; large-scale simulation with a complex breeding goal

Alternative Norwegian sheep breeding schemes were evaluated by stochastic simulation of a breeding population with about 120 000 ewes, considering the gain for an aggregate genotype including nine traits and also the rate of inbreeding. The schemes were: a scheme where both young unproven rams (test rams) and proven rams (elite rams) are used in artificial insemination (AI scheme), a scheme with test rams in natural mating in ram circles and elite rams (from one and a half years of age) in AI across all flocks in the country (NMAI2 scheme), a scheme where, in addition to testing rams, the youngest elite rams (one and a half years of age) are also used in natural mating in ram circles, while older elite rams are used in AI (NMAI1 scheme), and a scheme, acting as a control, where both test and elite rams are used in natural mating (NM scheme). Within the NMAI- and AI-schemes, experimentation was performed for percent ewes inseminated to elite rams v. test rams (EM%), numbers of ewes inseminated per elite ram (EAIn), and numbers of ewes mated per test ram by natural service (TNMn) or by AI (TAIn), respectively. With a restriction on the rate of inbreeding (⩽0.8% per generation), the AI scheme gave similar gain to the NMAI2 scheme (and about 40% more than did the NM scheme). Less gain was generated by the NMAI1 scheme, but it was still considerably more than for the NM scheme (about 25%). In the AI scheme, relatively few ewes (200/300) should be inseminated to each test/elite ram, and a low EM% should be chosen (10%). In the NMAI schemes, TNMn should be relatively high (40 to 50), combined with average and somewhat larger than average EAIn (NMAI2: 700 ewes, NMAI1: 900 ewes), and EM% medium (30%).     

Influence of eCG and reproductive management in the resynchronization of ovulation in dairy goats

Resynchronization protocols have been proposed as a way of shortening females’ unproductive time in the flock, with good results in cattle and sheep. In goats, initial studies have shown that a second progestogen device inserted before luteolysis and pregnancy diagnosis does not interfere with the corpus luteum lifespan or functionality. This study aimed to evaluate the follicular growth, ovulation pattern and pregnancy rate after insertion of a second and new progestogen device for resynchronizing, with or without equine Chorionic Gonadotrophin (eCG), submitted to natural mating (NM) or artificial insemination (AI) to propose a viable resynchronization protocol for dairy goats. A total of 38 multiparous Saanen goats underwent a short-term progesterone protocol [six days exposed to medroxyprogesterone acetate (MAP) intravaginal sponges + 200 IU eCG and 0.12 mg of cloprostenol sodium on the 5^th day + 0.025 mg of lecirelin 34 hours after sponge withdrawal] and, on day 16th after the ovulation, received a new MAP device which was retained until day 21. At this moment females were split into four groups: G_eCG+NM – 100 IU eCG with NM; G_Sal+NM – saline solution with NM; G_eCG+AI – 100 IU eCG with AI; and G_Sal+AI – saline solution with AI. Ultrasound scans were performed every 12 h from sponge withdrawal (day 21) until 108 h after sponge withdrawal (day 25) for follicular dynamics evaluation, at 240 h (day 31) for assessing the presence of active corpus luteum, and on day 60 for pregnancy diagnosis. No differences were found regarding ovulation time, synchronization and follicle size. However, G_eCG+NM presented a greater estrus manifestation rate (100%) and pregnancy rate (62.5%) when compared to G_Sal+AI. In conclusion, resynchronization protocols in dairy goats may present satisfactory results.     

Effect of prebreeding maintenance diet on subsequent reproduction by artificial insemination in alpine and Saanen goats

The objective of this study was to investigate the effect of 2 levels of prebreeding nutrition on reproduction in yearling does artificially inseminated (AI) by the intrauterine laparoscopic method. Forty-two does (Alpine = 22 and Saanen = 20) were randomly penned in groups of 7 and were fed 1 of 2 diets. The diets contained 3.2 Mcal DE/d (MAINT) or 3.5 Meal DE/d (HIGH), which was 10 and 20% higher than the National Research Council recommendations for maintenance requirements. The does were on the 2 feed treatments for 8 wk, after which the MAINT group was switched to the HIGH group diet. A week later, they were fitted with Veramix sponges to synchronize estrus. The sponges were removed from 22, 10 and 10 randomly picked does after 17, 22 and 23 d, respectively. All the does showed estrus within 48 h of removing the sponges. Previously frozen Alpine or Saanen semen (0.5 ml) was deposited into the uterus of does exhibiting standing estrus after anesthetizing them with zylazine and ketamine. Pure breeding was practiced. All the does lost weight prior to breeding. Seventeen does (41%) conceived and kidded by AI while the rest returned to estrus about 23 d later. A significant difference (P < 0.05) in the kidding percentage was observed between the 2 breeds (Alpine = 64% and Saanen = 16%), while the kidding percentage between the 2 diets did not differ (P > 0.05). Of the does that kidded, seven (41%) had singletons, eight (47%) had twins, one had triplets and one had quadruplets. Average litter size (kids/doe kidding) by AI was 1.76. Although the does lost weight prior to breeding, this did not affect their reproduction.     

Influence of cage or pen housing on carcass traits and meat quality of rabbit

Carcass traits and meat quality of rabbits reared in conventional cages (0.385 m2), small pens (0.662 m2) or large pens (4.052 m2) at a similar stock density of 15 rabbits/m2 were compared (n = 30 per group). Pens contained an elevated platform. Slaughter weight (SW; P < 0.01) and cold carcass weight (P < 0.05) decreased in the order of Cage < Small pen < Large pen groups. SW and cold carcass weight were 7% lower in rabbits housed in large pens than in cages. Dressing out and meat-to-bone ratio were not influenced by the housing system. Percentage of fat deposits was highest in caged rabbits (+0.15 point for scapular fat and +0.26 point for perirenal fat compared to rabbits reared in large pens P < 0.05). Rabbits housed in large pens had a bigger proportion of hind part (+1 point), and meat colour was shifted towards greater a* values (P < 0.01) compared to caged rabbits. Water holding capacity and shear test parameters in longissimus lumborum muscle, lipid content and shear test parameters of abductor cruralis cranialis, biceps femoris and semitendinosus muscles were not affected by the housing system. Tibia and femur bone moment of inertia increased in the order of Cage < Small pen < Large pen groups (P < 0.05), whereas elastic modulus, which is a measure of intrinsic stiffness, was highest in caged rabbits. This study showed that large pen housing altered carcass traits independently and increased meat redness and fracture resistance of tibia and femur.     

Ovulation frequency among sows group-housed during late lactation

Ovulation frequency during late lactation was determined among 114 sows from four commercial farms that group-housed the sows from about 3 weeks of lactation until weaning (G-farms), and among 21 sows from one farm that kept the sows individually penned throughout lactation (C-farm). Ovulation frequency was determined by applying a progesterone assay on faecal samples collected at weekly intervals from time of grouping until 3 weeks after weaning. The groups consisted of 11–22 sows and boar contact was not allowed during the 5–6 week lactation period. G-farm sows were fed ad libitum while C-farm sows were provided with a restricted food ration. During the group-housing period, 28% of the G-farm sows ovulated, whereas none of the singly housed sows ovulated during the corresponding period (P = 0.005). Ovulation frequency varied considerably between sow groups (0–54%) (P = 0.004), owing partly to differences in age. Not a single primiparous sow ovulated, whereas ovulation frequency among second to fourth parity sows and older sows (fifth parity and over) was 6% and 48%, respectively (P < 0.001). At the time of grouping and weaning, neither backfat thickness nor litter size differed between the sows that ovulated and those that were anoestrous. Preweaning mammary gland atrophy, indicating that milk production had ceased, was noted in 16% of the G-farm sows that ovulated but in only one (1%) of the anoestrus sows. Only 65% of the sows showing lactational ovulation were mated within 10 days after weaning. By contrast, 87% of the G-farms sows that were anoestrus during lactation and 100% of the C-farm sows were mated within this period.