Strategies for rapid rebreeding of lactating ewes in the spring

Rapid rebreeding of winter- and spring-lambing ewes is essential if ewes are to lamb more than once per year, but fertility of lactating ewes is often low and early weaning of lambs may be undesirable in forage-based production systems. Selection to improve fertility in spring matings has been successful and led to development of ewes with a reduced seasonal anestrus. Potential for rapid rebreeding of lactating out-of-season breeding (OOS) ewes was tested in three studies. In Experiment 1, effects of short-term lamb removal on rebreeding was evaluated over 2 years using 71 January-lambing OOS ewes. At an average of 63 days postpartum, 36 ewes had lambs removed for 72 h, and all ewes were joined with rams. Circulating progesterone levels indicated that 74% of ewes ovulated before lamb separation; 91% of ewes mated within 5 weeks of ram exposure, 85% were diagnosed as pregnant and 75% lambed. The average interval between lambings was 225 days. In contrast to results observed in cattle, none of the measured variables was affected by lamb separation (P>0.20). Experiment 2 compared rebreeding performance of 24 OOS and 23 St. Croix ewes that lambed in January and averaged 60 days postpartum at ram introduction. More OOS ewes ovulated, mated and became pregnant during the first 21 days of ram exposure (83.3%, 58.3%, and 41.7%, respectively; P<0.001) compared with St. Croix ewes (26.1%, 0%, and 0%, respectively). After 39 days of ram exposure, pregnancy rates still favored OOS ewes (66.7% v. 39.1%; P=0.06), but the percentage of ewes that lambed did not differ (P>0.20) between OOS (47.8%) and St. Croix ewes (34.8%). In the third study, 34 March-lambing OOS ewes were exposed to rams on May 3 at an average of 40 days postpartum to characterize their reproductive performance. After 39 days of ram exposure, 52.9±8.7% of the ewes had mated, and 38.2±8.5% were diagnosed as pregnant. However, only 20.6±7.0% of the ewes produced viable lambs, suggesting a high level of uterine insufficiency. Spring fertility of lactating OOS ewes in these studies was one of the highest reported in the literature and indicated that selection for fertility in spring mating would improve reproductive performance in accelerated lambing programs. However, exposure of lactating OOS ewes to rams at 30 to 50 days postpartum was associated with high prenatal lamb mortality.     

The Type 1 Diabetes - HLA Susceptibility Interactome - Identification of HLA Genotype-Specific Disease Genes for Type 1 Diabetes

Background

The individual contribution of genes in the HLA region to the risk of developing type 1 diabetes (T1D) is confounded by the high linkage disequilibrium (LD) in this region. Using a novel approach we have combined genetic association data with information on functional protein-protein interactions to elucidate risk independent of LD and to place the genetic association into a functional context.

Methodology/Principal Findings

Genetic association data from 2300 single nucleotide polymorphisms (SNPs) in the HLA region was analysed in 2200 T1D family trios divided into six risk groups based on HLA-DRB1 genotypes. The best SNP signal in each gene was mapped to proteins in a human protein interaction network and their significance of clustering in functional network modules was evaluated. The significant network modules identified through this approach differed between the six HLA risk groups, which could be divided into two groups based on carrying the DRB1*0301 or the DRB1*0401 allele. Proteins identified in networks specific for DRB1*0301 carriers were involved in stress response and inflammation whereas in DRB1*0401 carriers the proteins were involved in antigen processing and presentation.

Conclusions/Significance

In this study we were able to hypothesise functional differences between individuals with T1D carrying specific DRB1 alleles. The results point at candidate proteins involved in distinct cellular processes that could not only help the understanding of the pathogenesis of T1D, but also the distinction between individuals at different genetic risk for developing T1D.     

Progesterone administration reduces the behavioural and physiological responses of ewes to abrupt weaning of lambs

Abrupt weaning, a usual management in sheep productive systems, may provoke behavioural and physiological responses indicative of stress in ewes and lambs. Progesterone (P4) has anxiolytic and sedative effects through the union of its metabolites that contain 3α-hydroxyl group to the γ-aminobutyricacid_A receptor. Our first aim was to determine whether P4 administration reduces the behavioural and physiological responses of ewes to abrupt weaning of lambs. A complementary aim was to determine whether P4 treatment affects the milk yield and composition of ewes, and the BW of their lambs. In experiment 1, seven ewes received P4 treatment for 32 days (group E1-P4), and eight ewes remained as an untreated control group (group E1-C). BW of the lambs was recorded during P4 treatment. Lambs were weaned at 59 days (Day 0 = weaning). The main behaviours of the ewes before and after weaning were recorded using 10 min scan sampling. The ewes’ serum total protein, albumin and globulin concentrations were measured before and after weaning of the lambs. In experiment 2, milk yield and composition were determined in two different groups of six ewes treated with P4 (group E2-P4) for 16 days and in five untreated controls (group E2-C). The BW of lambs increased with time (P = 0.001) in both groups and did not differ. The percentage of observations in which the ewes were seen pacing on Day 0 was greater in the E1-C group than in the E1-P4 group (P = 0.0007). Similarly, the percentage of observations in which the ewes were recorded vocalizing on Day 0 was greater in the E1-C group than in the E1-P4 group (P = 0.04). The percentage of observations in which E1-C ewes were recorded lying did not change from Days 0 to 1; however, it increased in E1-P4 ewes. Total serum protein concentration did not change in E1-P4 ewes from Days 0 to 3, although a decrease was seen in E1-C ewes (P = 0.04). Serum globulin concentration was greater in E1-P4 ewes on Day 3 than in E1-C ewes (P = 0.0008). In experiment 2, there were no differences between E2-P4 and E2-C ewes in terms of milk yield, protein, fat and lactose content. Progesterone administration reduced the behavioural and physiological responses of ewes to abrupt weaning of lambs, and this effect was not mediated by changes in milk yield and composition, or by lambs’ BW.     

The periparturient rise in fecal egg counts in three strains of Florida native ewes and its value in predicting resistance of lambs to Haemonchus contortus

The periparturient rise in fecal egg counts in three strains of Florida Native ewes and its value in predicting resistance of lambs to Haemonchus contortus. International Journal for Parasitology16: 185–189. Significant (P < 0.05) differences in the magnitude of the periparturient rise in fecal egg counts (PPR) occurred in ewes of three strains of Florida Native sheep. Non-lambing ewes (n = 12) and lactating University strain ewes (n = 31), a strain selected over a 26-year period for parasite resistance by survival at pasture without anthelmintic treatment, had lower fecal egg counts than ewes of either Maxcy strain (n= 17), a commercial strain treated regularly with anthelmintics, or Backlinie strain (n = 16), a strain of Florida Native sheep that had some crossbreeding to Hampshire and Suffolk in their genotype and were regularly treated with anthelmintics. Whereas both Maxcy and Backlinie ewes showed a pronounced PPR, none occurred in non-lambing ewes (n=12) and the slight rise in fecal egg counts observed in University ewes was not significantly different from that of the non-lambing ewes. Backlinie ewes having twin lambs (n = 5) had a higher PPR than Backlinie ewes with single lambs (n = 11) or Maxcy ewes with single lambs (n = 15), but all three groups had higher PPRs than University ewes with single lambs (n = 27). No differences occurred in fecal egg counts of non-lambing ewes regardless of strain. Six weeks after weaning fecal egg counts of all ewes were uniformly low regardless of strain or prior lactation status.Ram lambs born to these ewes showed no significant strain differences in Haemonchus contortus burdens after experimental infection, deworming with levamisole and reinfection, although University lambs (n= 13) had lowest mean worm burdens at necropsy (2437) followed by Maxcy lambs (n= 12, mean =3106) and Backlinie lambs (n= 13, mean =3670). There was no significant correlation between worm burdens in these lambs and the magnitude of the PPR in their dams. Eight to 16 weeks after turn out to a common parasite-infested pasture ewe lambs (n = 13) born to University ewes had lower fecal egg counts than similar ewe lambs (n=8) born to Backlinie ewes. Prior to this time differences were not significant and egg counts were generally low. The magnitude of the PPR in their dams was not significantly correlated with fecal egg counts or PCVs of individual ewe lambs.     

Mob size of single-bearing or twin-bearing Merino ewes at lambing may not influence lamb survival when feed-on-offer is high

Limited research has suggested that higher lambing densities increase interference from foreign ewes at lambing which disrupts the ewe-lamb bond and compromises lamb survival. This may be particularly evident in mobs of twin-bearing ewes compared to single-bearing ewes because a greater number of lambs are born per day. Therefore, we hypothesised that; (i) decreasing the mob size of ewes at lambing has a greater impact on the survival of twin-born lambs than single-born lambs; (ii) the relationship between mob size and lamb survival can be explained by differences in the rate of interaction with foreign ewes and lambs at lambing; and (iii) ewes will utilise a limited area of the paddock at lambing and thus lambing density will be defined by the distribution of ewes in the paddock rather than the paddock area. Merino ewes were allocated into a 2×2 factorial combination of ewe pregnancy status (single- or twin-bearing) and mob size (high (n=130 ewes) or low (n=50 ewes)) on day 140 from the start of joining. Each treatment had two replicates excepting the low mob size for twins which had a third replicate. Ewes lambed at a stocking rate of 11 ewes/ha. Feed-on-offer during lambing exceeded 2400 kg dry matter (DM)/ha. Ewe-lamb behaviour was observed and dead lambs were autopsied over 11 days during the peak of lambing. The distribution of ewes in each paddock was recorded every 2 h during daylight hours by counting the number of ewes occupying 2500 m² grids. The proportion of ewes and their newborn progeny which interacted with foreign ewes at lambing did not differ between the high and low mob sizes for single- (24.9% v. 20.8%) or twin-bearing ewes (14.3% v. 19.6%; P=0.74). Similarly, interaction with foreign lambs did not differ between the high and low mob sizes for single- (14.5% v. 25.2%) and twin-bearing ewes (34.5% v. 26.4%; P=0.44). The distribution of ewes within the paddock did not differ between treatments (P=0.95). On average, single-bearing ewes which lambed at the high and low mob sizes occupied 34% and 36% of the paddock during daylight hours, and the corresponding values for twin-bearing ewes were 40% and 43%. Survival of twin-born lambs was lower than single-born lambs (75.3% v. 87.9%; P<0.01), however, lamb survival was not influenced by mob size regardless of birth type. These results suggest that higher mob sizes may not compromise lamb survival when feed-on-offer during lambing exceeds 2400 kg DM/ha.     

Synchronization of estrus with short- and long-term progestagen treatments and the use of GnRH prior to short-term progestagen treatment in ewes

The objective of the present study was to determine the efficacy of the synchronization of estrus using short- and long-term progestagen treatments in ewes at the onset of the breeding season, and to evaluate the effect of the exogenous GnRH administration immediately prior to short-term progestagen treatment on the reproductive performance. A total of 240 Tahirova cross-bred ewes, aged 18–24 months, and 40 rams, aged 2–4 years-old, were used in the trial. Ewes were divided equally into 3 groups (n = 80 per group). Intravaginal progestagen sponges containing FGA (30 mg) were inserted in the ewes for 7 d in the FGA1 (short-term) and GnRH treatment groups, and for 12 d in the FGA2 group (long-term). The ewes in the GnRH group received 10.5 μg busereline acetate i.m. at the time of sponge insertion. Tiaprost tromethamol (PGF_2α; 0.294 mg) and eCG (400 IU) were injected i.m. on the 6th day of progestagen treatment in the GnRH and FGA1 groups, and on the 11th day in the FGA2 group following sponge insertion. All ewes were hand-mated once at the detection of estrus. The estrous response, fertility rate, multiple birth rate and litter size recorded was 88.7, 87.3, 51.6% and 1.6 in the FGA1 group, 92.5, 71.6, 50.9% and 1.5 in the FGA2 group, and 96.2, 89.6, 71.0% and 1.8 in the GnRH group, respectively. No significant difference in estrous response between the groups was recorded, but the fertility rate in the FGA1 and GnRH groups was significantly (P < 0.05) higher than in the FGA2 group. The occurrence of multiple births and litter sizes were significantly (P < 0.05) higher in the GnRH group, compared to both the FGA1 and FGA2 groups, with the number of single lambs being significantly (P < 0.05) higher in the FGA1 (48.4%) and FGA2 (49.0%) groups than in the GnRH (29.0%) group. However, the differences recorded between any of the groups in terms of the number of twin and triplet lambs were insignificant. In conclusion, it can be said that estrous synchronization using the 12-d-FGA-eCG-PGF_2α regimen could be replaced with the 7-d-FGA-eCG-PGF_2α regime in sheep at the onset of the breeding season. However, the combination of GnRH with the latter regimen (7-d-GnRH-FGA-eCG-PGF_2α) increased the multiple birth rate and litter size in the ewes.     

Survival of fertilized ova from ewe lambs and adult ewes in the uteri of ewe lambs

The cause of fertility differences between ewe lambs and adult ewes following natural oestrus were studied in Romneys. Insemination was determined by anterior vaginal swabbing. Fertilized ewe-lamb ova were returned to donor animals along with one matched fertilized adult ewe ovum and lambings were recorded. Ewe-lamb ova were less likely (P<0.01) to survive to term compared with adult ewe ova. Insemination failure, fertilization failure and anovular oestrus were minor sources of reproductive wastage.It is concluded that reduced ovum quality appears to be the major cause of the lower fertility in naturally ovulating ewe lambs compared with adult ewes.     

Control of oestrus in ewe lambs and yearling ewes with medroxyprogesterone acetate and fluorogestone acetate

Two experiments were conducted in a large flock of Berrichon purebred and Romanov × Berrichon F₁ crossbred ewes. In experiment 1, 157 ewe lambs were placed in six groups according to season of mating and maternal breed. Within each group equal numbers of females were treated with either medroxyprogesterone acetate (MAP) or fluorogestone acetate (FGA)-impregnated sponges for 14 days; dosage of PMSG at the time of sponge removal was 500 and 300 I.U. respectively for pure and crossbred. In experiment 2, 111 dry yearling ewes of the Berrichon breed were involved, of which 35, 51 and 25 had either a short lambing to treatment interval (approximately 3 months), a long lambing to treatment interval (approximately 6 months), or were primiparous or nulliparous. They were also treated either with MAP or FGA.The conception rates were extremely high (overall near 86%) in ewe lambs and not significantly affected by seasons or breeds or treatments. Prolificacy and number of lambs per ewe mated were higher in the F₁ crossbred group than in pure Berrichon females (respectively 1.91 vs. 1.34 lambs/mated ewe). No significant difference between the two progestagens could be observed for any of the productivity criteria. Fertility was equally satisfactory in yearlings (overall near 85%) irrespective of the interval between lambing and mating. However, the fertility of the nulliparous ewes (those that failed to conceive as ewe lambs) was significantly lower (72%). The number of lambs per ewe mated was 1.78 in yearlings with a 6-month interval from lambing to mating but was not significantly different from the numbers recorded in the other two groups (1.37 and 1.36). As in experiment 1, there was no difference in the results obtained after either of the two progestagen treatments.In conclusion, progestagen treatment has been shown in both ewe lambs and yearlings to be a very effective means of increasing lamb production in large flocks. This was achieved in ewe lambs regardless of the season and, in dry yearling ewes, regardless of the interval from lambing to mating in the anoestrous season.     

Behavior of parturient ewes in group-lambing pens with and without cubicles

Maternal behavior was examined in 301 multiparous ewes (2–6 years of age) that were of predominantly Suffolk or Targhee breeding. The ewes gave birth in either a normal lambing pen (control) or in a similar pen modified by the addition of 8 cubicles (cubicles). Approximately 100 ewes were present in each pen at a time, creating a density of 1 ewe m^?2.Within the cubicle treatment, comparisons were made between the ewes which gave birth inside a cubicle (CUB-I, n = 64) and those that gave birth outside the cubicles (CUB-O, n = 92). CUB-I ewes spent less time moving about (P<0.01), travelled less distance (P<0.001), investigated fewer potential birth-sites (P<0.001) and spent more time in the cubicles (P<0.001) during the 60 min prior to giving birth than did CUB-O ewes. After giving birth, CUB-I ewes remained close to their lambs, which always remained in the cubicles. This resulted in CUB-I ewes and their lambs remaining closer to each other and to the birth-site than CUB-O ewes and lambs (P<0.001). CUB-I ewes were rarely interfered with by other ewes (17 vs. 82% interference for CUB-I and CUB-O ewes, respectively) and had fewer (0) lambs separated or stolen from them than did CUB-O ewes (13 of 144 lambs).In comparing the cubicle system and the control pen, it was found that interference with ewes and lambs was less in the cubicle treatment (P<0.01). In the cubicle system, there tended to be fewer lambs separated from their dams (5.4 vs. 9.6%) and less stealing of lambs (3.1 vs. 5.2%) compared to the control pen. It is concluded that the use of cubicles under these conditions reduces the incidence of poor maternal behavior in ewes.     

Artificial insemination of ewes with frozen-thawed semen at a synchronised oestrus. 2. Effect of dose of spermatozoa and site of intrauterine insemination on fertility

Three experiments were conducted to examine the effect of dose of inseminate, number of uterine horns inseminated and site of insemination on subsequent fertility of Merino ewes after synchronisation of oestrus, with progestagen-impregnated sponges (inserted for 12 days) and an injection of PMSG, and intrauterine insemination with frozen-thawed semen.The percentages of ewes lambing after insemination with 0.5, 5, 25 and 50 × 10⁶ spermatozoa were 29.3, 26.8, 56.3 and 62.1% respectively. A similar trend was observed in a second test resulting in 23.5, 38.8 and 53.1% ewes lambing after insemination with 5, 10 and 20 × 10⁶ spermatozoa respectively.The percentage of ewes lambing was higher for ewes inseminated in two uterine horns than one horn (76.8 vs. 44.9, P < 0.001). When semen was deposited in the tip, middle and bottom of the uterine horn, the percentages of ewes lambing and lambs born per ewe inseminated were 43.6 and 52.7, 52.8 and 84.9, and 41.2 and 64.7% respectively. Although site of insemination did not affect the percentage of ewes lambing, the percentage of lambs born per ewe inseminated was higher after insemination in the middle of the uterine horn than at the other sites (P < 0.001).     

Early prepartum shearing increases milk production of wool sheep and the weight of the lambs at birth and weaning

The use of mid prepartum shearing has been described as a possible tool to increase the weight of the lambs at birth and at weaning. The effect of prepartum shearing (53 days of gestation) on production and chemical composition of milk, weight of the lambs at birth and weaning and growth rate were evaluated in this trial. Twenty Polwarth ewes were inseminated with rams of the same breed in May (autumn), 2009. All ewes bore singletons and were maintained together under cultivated grazing conditions, during the experimental period. The ewes were allocated to two treatments groups, based on expected day of parturition, body weight and BCS of the dams. Ten ewes were shorn at 53 days of gestation (S53) and 10 ewes were kept unshorn during gestation (US). Milking of the ewes was recorded 7 days after parturition, and this was repeated weekly for 15 weeks. Milk production of the S53 ewes was 22.2% higher (P < 0.05), when compared to US control ewes - with no change in the milk composition. At lambing, the lambs born to the S53 ewes were 1.41 kg (P < 0.05), and at weaning 4.5 kg heavier (P < 0.05), than lambs born to US ewes. In conclusion, it can be said that the higher weaning weight of the S53 lambs was the result of both a higher birth weight and an increased growth rate up to weaning in part, due to an improved milk production of the ewes.     

Ram-induced oestrus and ovulation in lactating and weaned Corriedale ewes

Two experiments were conducted in consecutive years in which recently (Experiment 1) or temporarily (Experiment 2) weaned ewes and matched post-partum non-lactating flockmates (DRY) were exposed to a stimulus group of rams and oestrous ewes (10 and 20 in Experiment 1, 20 and 20 in Experiment 2) for 28 days in spring. Lactating ewes (n = 130) in Experiment 1 were isolated from their lambs 4 (W-4), 2 (W-2), 1 (W-1) or 0 (W-0) days in advance and exposed along with a group of 32 DRY flockmates. Lactating ewes in Experiment 2 (n = 230) were allocated to an unreplicated factorial of two levels of temporary weaning before stimulation (B0: control; B24: lambs removed 24 h before stimulation) by four levels of ewe-lamb contact imposed at the start of the stimulation (A0: control; A12, A24 and A36: lamb-ewe separation during the initial 12, 24 or 36 h of exposure); DRY ewes (n = 54) acted as an augmented factorial control. Oestrus (rump marks) and ovulation (laparoscopy on day 5 and on day 28 (Experiment 1) or day 32 (Experiment 2)) were recorded. Ovulation and oestrous responses in Experiment 1 were similar for DRY (90.6% and 55.2%, respectively) and recently weaned ewes (83.8% and 53.7%, respectively). Amongst recently weaned ewes, the immediate ovulation response to the rams and the proportion of ewes still cycling by day 28 tended to be lower (P = 0.065 and P = 0.011) in ewes weaned on the day of ram exposure (71.9% and 54.8% v. 87.8% and 80.0%, respectively). Ovulation rate was lower (P < 0.003) in W-2 ewes (1.3 ± 0.10) than in the other recently weaned groups. In Experiment 2, ovulation (83.3%) and oestrous (68.9%) responses in DRY ewes were higher (P = 0.022 and P = 0.053, respectively) than in lactating ewes (66.2% and 51.0%, respectively). More ewes ovulated (P = 0.036) in B24 (70.5%) than in B0 (61.8%). Ewes having their lambs returned 12 h after the onset of stimulation (A12) had poorer ovulation responses (54.9%) than control ewes (A0, 72.9%, P < 0.05); this was probably associated to lamb restitution after the sunset. Main conclusions were that (i) the presence of the lambs is a depressing factor of both ovulation and oestrous responses to the ram effect in lactating ewes, (ii) the ovulation response of lactating ewes will probably benefit from removing lambs for a period of 24 h before the onset of stimulation, (iii) until additional information becomes available, temporary weaning protocols should be designed avoiding lamb restitution during the night.     

A review of the effects of the Booroola gene (FecB) on sheep production

Booroola Merino (B^oM) ewes have a high ovulation rate and litter size which in 1980 was postulated to be due to the effects of a major gene (FecB). This was confirmed in breeding experiments and FecB was subsequently shown to be due to a mutation (BMPR-1B) on chromosome 6. The B^oM originated from an Australian commercial fine wool Merino flock (Booroola) and has been used in crossing experiments and for introgression of FecB into many breeds around the world to improve fecundity. The mutation has recently been found in native sheep breeds in India, China and Indonesia and it is likely that FecB in the Australian B^oM was derived from importations of Garole sheep from India in 1792 and 1793.The effects on production traits of the FecB mutation in a range of genetic comparisons, environments and production systems are reviewed. Comparisons involving B^oM crosses with various other breeds and contrasts of FecB homozygous (BB), heterozygous (B+) and non-carrier (++) genotypes in comparable background genotypes, including non-B^oM, have been summarised from 45 reports. The weighted mean effect for ewes carrying one copy of FecB (B+) was +1.3 (range +0.8 to +2.0) for ovulation rate and +0.7 (range +0.4 to +1.3) for litter size. The effect of a second copy (BB) was generally additive for ovulation rate, with little or no increase in litter size for BB ewes among B^oM crosses. However there was generally a further increase in litter size for BB ewes of about half the effect of one copy (B+) in the Indian and Chinese breeds. Poor lamb survival and lamb growth reduced the number of lambs weaned and total weight of lamb weaned by B+ ewes. Most studies still showed a small advantage for B+ ewes, although several reported negative effects. While embryo survival declines at higher ovulation rates, the effects of FecB per se are equivocal. There is some evidence of a higher non-pregnancy rate among homozygous BB ewes. Most studies reported lower birth weight and growth rate from B^oM cross lambs and lambs from crossbred ewes introgressed with FecB. However it is difficult to separate the effects of low background genetic merit for growth of the B^oM and the lower birth weight and growth rate of lambs from larger litters from the genetic effect of carrying FecB. There was little or no difference in growth rate between BB, B+ and ++ genotype lambs. For other traits including, seasonal oestrous activity, carcass and meat quality and wool production, there was no evidence of major effects of FecB. The opportunities for management and nutritional modification of FecB expression and implications for industry adoption are briefly discussed.     

Nutritional status of adult ewes during early and mid-pregnancy. 2. Effects of supplementation with selenised yeast on ewe reproduction and offspring performance to weaning

The objective of this study was to determine the effects of selenium (Se) supplementation of mature ewes in the period from day −14 to day 90 post mating on Se status, productivity and viability of ewes and their offspring. Multiparous crossbred ewes (n = 82) were randomly assigned to receive a standard dried grass-based diet (control) or dried grass diet supplemented with 1 g of selenised yeast (Selplex®), providing 0.5 mg Se per ewe per day. After day 90 post mating, all ewes were offered grass-based diets supplemented with a standard multivitamin and mineral mix, up to lambing. Ewes that were fed additional Se had increased (P < 0.001) activity of glutathione peroxidase enzyme (GPx) and increased plasma Se concentrations throughout the treatment period. At lambing, GPx activity of supplemented ewes was higher (P < 0.001) than that of controls. Twenty-four hours after birth, lambs of ewes given Se had higher (P < 0.001) concentration of Se in plasma, greater (P < 0.001) activity of GPx and better (P < 0.01) immune status. Lambs of ewes that received supplementation showed a faster progression to stand than control lambs (P < 0.05), independent of maternal behaviour which was not affected. Supplementation reduced perinatal lamb mortality (0.04 v. 0.17; P < 0.05). However, overall mortality from birth to weaning was unaffected (P > 0.05). Supplemented ewes weaned lambs on average 2 kg heavier than control ewes, due to the higher (P < 0.05) growth rates achieved by their offspring. In conclusion, for ewes with a marginal Se status, an organic source of Se supplemented throughout pregnancy, compared with supplementation only in the last trimester, positively affected measures of lamb viability and survival.     

HLA Alleles Influence the Clinical Signature of Amoxicillin-Clavulanate Hepatotoxicity

Background and Aim

The genotype-phenotype interaction in drug-induced liver injury (DILI) is a subject of growing interest. Previous studies have linked amoxicillin-clavulanate (AC) hepatotoxicity susceptibility to specific HLA alleles. In this study we aimed to examine potential associations between HLA class I and II alleles and AC DILI with regards to phenotypic characteristics, severity and time to onset in Spanish AC hepatotoxicity cases.

Methods

High resolution genotyping of HLA loci A, B, C, DRB1 and DQB1 was performed in 75 AC DILI cases and 885 controls.

Results

The distributions of class I alleles A*3002 (P/Pc = 2.6E-6/5E-5, OR 6.7) and B*1801 (P/Pc = 0.008/0.22, OR 2.9) were more frequently found in hepatocellular injury cases compared to controls. In addition, the presence of the class II allele combination DRB1*1501-DQB1*0602 (P/Pc = 5.1E-4/0.014, OR 3.0) was significantly increased in cholestatic/mixed cases. The A*3002 and/or B*1801 carriers were found to be younger (54 vs 65 years, P = 0.019) and were more frequently hospitalized than the DRB1*1501-DQB1*0602 carriers. No additional alleles outside those associated with liver injury patterns were found to affect potential severity as measured by Hy’s Law criteria. The phenotype frequencies of B*1801 (P/Pc = 0.015/0.42, OR 5.2) and DRB1*0301-DQB1*0201 (P/Pc = 0.0026/0.07, OR 15) were increased in AC DILI cases with delayed onset compared to those corresponding to patients without delayed onset, while the opposite applied to DRB1*1302-DQB1*0604 (P/Pc = 0.005/0.13, OR 0.07).

Conclusions

HLA class I and II alleles influence the AC DILI signature with regards to phenotypic expression, latency presentation and severity in Spanish patients.     

Distance recognition in ewes and lambs kept permanently indoors or at pasture

We tested the ability of Merino and Merino × Romanov ewes and lambs to recognise each other at a distance when given the choice between an alien partner and their own. Two groups of animals were studied. In the first group, multiparous ewes and their lambs were housed permanently indoors at a stocking-rate of 1 ewe/2 m². In the second group, ewes and lambs were run permanently outside in a paddock at a stocking rate of 1 ewe/500 m². Of animals living outside, 87% of ewes recognised their own lamb (100% of multiparous dams versus 84% of primiparous ones, P = 0.02). This differed significantly from a random choice. By contrast, the proportion of correct choices by ewes living inside (all multiparous) was significantly lower (64%) and did not differ from a random choice at the 5% level. Lambs reared outside recognised their dam in 95% of cases, versus 72% in lambs reared indoors (P = 0.01). Both frequencies differed significantly from a choice at random. It is concluded that the environmental conditions in which ewes and lambs are maintained can influence their ability to select their partners at a distance with the help of auditory and visual cues.     

Characterization of Major Histocompatibility Complex (MHC) DRB Exon 2 and DRA Exon 3 Fragments in a Primary Terrestrial Rabies Vector (Procyon lotor)

The major histocompatibility complex (MHC) presents a unique system to explore links between genetic diversity and pathogens, as diversity within MHC is maintained in part by pathogen driven selection. While the majority of wildlife MHC studies have investigated species that are of conservation concern, here we characterize MHC variation in a common and broadly distributed species, the North American raccoon (Procyon lotor). Raccoons host an array of broadly distributed wildlife diseases (e.g., canine distemper, parvovirus and raccoon rabies virus) and present important human health risks as they persist in high densities and in close proximity to humans and livestock. To further explore how genetic variation influences the spread and maintenance of disease in raccoons we characterized a fragment of MHC class II DRA exon 3 (250bp) and DRB exon 2 (228 bp). MHC DRA was found to be functionally monomorphic in the 32 individuals screened; whereas DRB exon 2 revealed 66 unique alleles among the 246 individuals screened. Between two and four alleles were observed in each individual suggesting we were amplifying a duplicated DRB locus. Nucleotide differences between DRB alleles ranged from 1 to 36 bp (0.4–15.8% divergence) and translated into 1 to 21 (1.3–27.6% divergence) amino acid differences. We detected a significant excess of nonsynonymous substitutions at the peptide binding region (P = 0.005), indicating that DRB exon 2 in raccoons has been influenced by positive selection. These data will form the basis of continued analyses into the spatial and temporal relationship of the raccoon rabies virus and the immunogenetic response in its primary host.     

Segregation of a major gene influencing ovulation in progeny of Lacaune meat sheep

Inheritance of the ovulation rate (OR) in the Lacaune meat breed was studied through records from a small nucleus of 36 hyper-prolific ewes screened on farms on the basis of their natural litter size, and from progeny data of three selected Lacaune sires. These sires were chosen at the AI centre according to their breeding values estimated for the mean and the variability of their daughters'' litter size. Non-carrier Lacaune dairy ewes were inseminated to produce 121 F1 daughters and 27 F1 sons. Twelve sons (four from each sire) were used in turn to inseminate non-carrier Lacaune dairy ewes providing 260 BC progeny ewes. F1 and BC progeny were brought from private farms and gathered after weaning on an experimental farm where ovulation rates were recorded in the first and second breeding seasons. With an average of 6.5 records each, the mean OR of hyper-prolific ewes was very high (5.34), and 38.4% of records showed a rate of 6 or more. F1 data showed high repeatability of OR (r = 0.54) within ewe, with significant variability among ewes. High OR (≥ 4) were observed in each family. A segregation analysis provided a significant likelihood ratio and classified the three founders as heterozygous. BC ewes also displayed high repeatability of OR (r = 0.47) and the mean OR varied considerably between families (from 1.24 to 1.78). Seven of the 12 BC families presented high-ovulating ewes (at least one record ≥ 4) and segregation analysis yielded a highly significant likelihood ratio as compared to an empirical test distribution. The high variability of the mean ovulation rate shown by a small group of daughters of BC ewes inseminated by putative carrier F1 rams, and the very high ovulation rate observed for some of these ewe lambs, confirmed the segregation of a major gene with two co-dominant alleles borne by an autosome. The difference between homozygous non-carriers and heterozygous ewes was about one ovulation on the observed scale and 2.2 standard deviations on the underlying scale.     

Polymorphism of insulin-like growth factor 1 gene and its association with litter size in Small Tail Han sheep

The insulin-like growth factor 1 (IGF1) gene was studied as a candidate gene for high prolificacy in sheep. Polymorphisms of 5' regulatory region and all four exons of IGF1 gene were detected in Small Tail Han (n?=?277), Hu (n?=?58), Texel (n?=?48) and Dorset (n?=?46) sheep by PCR-RFLP and PCR-SSCP analysis. A microsatellite polymorphic site and a restriction fragment length polymorphism were shown in the 5' regulatory region of IGF1 gene. The ewes with genotype 123/123?bp had 0.81 (P??0.05) in Small Tail Han sheep. These results preliminarily indicated that these polymorphisms of IGF1 gene could be used in molecular marker-assisted selection for sheep breeding programs.     

Behavioral patterns of domestic sheep and their relationship to coyote predation

Activity patterns between individuals in a large herd of domestic sheep (Ovis aries) were examined to determine whether or not behavioral characteristics predisposed certain individuals to coyote (Canis latrans) predation. Coyotes killed 73 of 958 lambs and 6 of 624 ewes between 24 April and 15 August 1975. Twenty ewes and 19 lambs died from non-predatory causes. Coyote-kills accounted for 79.3% of the lamb losses. The amount of time ewes spent at various activities differed significantly by age or genotype, but the behavior of ewes whose lambs were killed was remarkably similar to that of other ewes. Single lambs were more active and were killed proportionately more often than twins. Within litters in which one of the lambs was killed, the killed sibling tended to be more active. Coyotes killed proportionately more disabled lambs and lambs from disabled ewes than healthy lambs or lambs from healthy ewes. Reduced mobility of either a lamb or a ewe increased the probability of a lamb's being on the periphery of the bed-ground and, hence, the probability that it would be noticed and attacked by a coyote. Coyote predation on domestic sheep was related more to the chance of an animal's being on the periphery of the bed-ground than to the animal's behavioral characteristics.