Abstract: Estimates of breeding frequencies in wild populations occupy a central place in life-history studies, but they remain hard to obtain in snakes Capture–recapture procedures were carried out during 27 periods over 3 years in a large population of female asp vipers, Vipera aspis (317 marked individuals) Catchability was greater in reproductive females (264 ± 174 (SD) captures/year) than in nonreproductive females (176 ± 102) Three different methods were used to estimate breeding frequency: (i) the proportion of reproductive to nonreproductive females for each period (noncorrected estimates, NC) was measured; (ii) the ratio of the number of reproductive females to the total number of females was estimated using the CAPTURE program (catchability-corrected estimates, CE); (iii) breeding frequencies of marked individuals were observed in the field for 3 years (observed breeding frequency, OF) The results obtained with the three methods were different The NC procedure indicated that 63% of females breed

Abstract: The estimate of inbreeding for registered Holstein females born during 1990 was 5.1 f 0.4% for a random sample of 600 two-line pedigrees. Previously published estimates were 4.7% for 1970, 3.8% for 1976, and 4.3% for 1982 from similar samples of pedigrees. These estimates were calculated using a base of approximately 1884, or the initiation of herdbook registration in the US. The estimate of relationship between randomly paired females born during 1990 was 10.2 f 0.8%; relationships were 5.2% for 1970, 7.3% for 1976, and 9.8% for 1982. Average relationship within the breed increased significantly without a corresponding increase in inbreeding. Inbreeding was also estimated for alternative base years with 10-yr increments to determine the effect of base year on estimates of inbreeding. Using 1950 as the base year, inbreeding was estimated at 0.5% for 1970, 0.3% for 1976, 1.6% for 1982, and 2.1% for 1990. Estimates using 1920 as the base year were 2.0% for 1970, 1.9% for 1976, 2.3% for 1982, and 3.2% for 1990. More recent base years gave lower estimates of inbreeding, as expected, but showed an exaggerated percentage of increase in inbreeding from 1970 to 1990. However, the annual amount of increase of inbreeding from 1976 to 1990 was not significantly affected by time of base year and ranged from 0.08 to 0.12/yr. The five most influential bulls of the breed were Pawnee Farm Arlinda Chief 1427381, Round Oak Rag Apple Elevation 1491007, S-W-D Valiant 1650414, Osborndale Ivanhoe 1189870, and Sir Pietertje Ormsby Mercedes 4493 1; estimated direct relationships to the breed were 0.123, 0.122, 0.096, 0.083, and 0.074, respectively.

Abstract: To distinguish between ewe and lamb breed effects on prenatal growth, ease of parturition and early lamb behaviour, an embryo-transfer study was carried out using a hill breed (Scottish Blackface; liveweight: 54.25 +/- 1.03 kg, mean +/- s.e.m.) and a lowland breed (Suffolk; 80.33 +/- 1.52 kg) to obtain the four possible combinations of ewe and lamb. Data were collected from 38 Blackface ewes (18 with Blackface lambs and 20 with Suffolk lambs) and 41 Suffolk ewes (20 with Blackface lambs and 21 with Suffolk lambs); all ewes were given single embryos. Suffolk lambs had a significantly longer gestation than Blackface lambs (1.5 days, P < 0.01), regardless of ewe breed. Suffolk lambs also had a longer labour (20 min, P < 0.05) and were significantly more likely to require birth assistance (17/21, 81% of all assisted deliveries; P < 0.001), as were male lambs (19/21, 90%; P < 0.01). These variables were independent of ewe breed. Blackface lambs were significantly more active than Suffolk lambs in the first 2 h after birth; ewe breed had little effect on lamb behaviour. Blackface lambs stood twice as quickly as Suffolk lambs after birth (13 min v. 24 min; P < 0.001), and were significantly more likely to suckle within the first 2 h after birth (92% v. 66%; P < 0.05). The behavioural retardation of Suffolk lambs may be a consequence of their birth difficulty which increases their likelihood of suffering birth trauma and hypoxia at parturition. Together, these factors may increase the probability of neonatal death in these lambs.

Abstract: Milk yield and quality were measured on 139 Angus, Brahman, and reciprocal-cross cows grazing common bermuda grass or endophyte-infected tall fescue for 4 yr to evaluate interactions of direct and maternal breed effects and heterosis for these traits with forage environment. Milk yield was estimated by method of milking machine, and milk fat, protein, and somatic cell counts were evaluated in a commercial dairy laboratory. Monthly estimates were made beginning on an average d 61 of lactation and continued monthly for six estimates in 3 yr and five estimates in 1 yr. Data were averaged over month within year, and the model included sire breed, sire in sire breed, dam breed, forage, and age averages. Somatic cell counts were transformed using natural logarithms prior to analyses. Forage effects for milk yield were dissimilar among sire breed x dam breed subclasses (P < .10), resulting in higher levels of heterosis on common bermuda grass than on tall fescue. Maternal breed effects for milk yield favored Angus on bermuda grass (P < .05) but not on tall fescue, whereas direct breed effects were similar on both forages and favored Brahman. Milk fat was reduced on tall fescue compared to bermuda grass by an average of .6% (P < .01), and direct breed effects were similar across forages and averaged 1.04% (P < .01) in favor of Brahman. Heterosis and maternal breed effects for milk fat were not important. There was little evidence of direct and maternal breed effects or heterosis for milk protein or somatic cell counts. These data suggest that heterosis for milk yield is larger on common bermuda grass than on tall fescue and that grazing endophyte-infected tall fescue is detrimental to milk fat.

Abstract: Crossbreeding parameters and variance components were estimated for lactation and reproductive traits of crosses between the Sahiwal, Brown Swiss and Ayrshire breeds in a dairy herd in sub-humid coastal Kenya. An individual animal model urns fitted to the data with a fixed effect for 20 distinct breed crosses. The estimates of breed cross means were then regressed on average breed content, expected average heterozygosity and recombination loss to determine the additive breed contributions, and the contributions of dominance and epistasis to heterosis. It was estimated that the Sahiwal contributed about 1345 kg (proportionally 0·33) less milk per lactation than the Brown Swiss. The Ayrshire was intermediate. The large amount of heterosis from the crosses of the Sahiwal (Bos indicusj and Bos taurus breeds more than compensated for the lower additive value of the Sahiwal when used in a three-breed rotational cross or synthetic. Heterosis amotig Bos taurus breeds was negligible. Estimates of the maternal heterosis and recombination loss (epistasis) were not significant, although the latter were consistently large and positive. It was concluded that the heterosis between the zebu and European breeds was mainly due to dominance effects. Estimates of heritability for milk yield traits were low (around 0·09 to 0·13) compared with other studies, although estimates of repeatability (around 0·29 to 0·33) were similar to results from the literature, indicating that the accuracy of estimated breeding values in this crossbred herd was reduced because of the non-additive genetic effects. The genetic improvement of crossbred herds is discussed.

Abstract: Fifty (ten per breed) Merino, Polwarth, Corriedale, Romney Marsh and Texel lambs were castrated at 30 days of age and raised up to weaning (ten weeks) on native pasture (mainly composed by Paspalum notatum Flugge and Axonoplus qffinis Chase) in the Southern (Bage, RS) region of Brazil. Following weaning, the animals were feedloted during one week and each lamb was daily fed 200 grams of a diet containing 17% of crude protein and 75% of dry matter basin. The animals were then moved to pasture up to 225 days of age when they were slaughtered to compare their live weight as a total and its components. Live weight was influenced by genotypes. This effect might not be observed in absolute numbers, but in percentage (head), or vice-versa, as shown by heart, lungs and liver. The Texel breed showed higher absolute values as compared to Merino. Polwarth, Corriedale and Romney Marsh. Percentualy, this superiority was only observed in carcass. Merino and Polwarth showed higher skin percentage, as compared to other breeds.

Abstract: Tick resistance in three breeds of cattle, two indigenous breeds (Arssi and Boran) and one Boran x Friesian cross-breed, were compared following natural tick infestations at Abernossa ranch in Ethiopia. The local Arssi breed was found to have the highest tick resistance, followed by the Boran breed, whereas the Boran x Friesian was the least resistant. Over a period of 12 months, from October 1991 to September 1992, a total of 32 897 ticks composed of four genera were collected from the animals. The four most abundant tick species were Amblyomma variegatum (61.7%), Boophilus decoloratus (16%); Rhipicephalus evertsi evertsi (16.3%) and Hyalomma marginatum rufipes (3.7%). Furthermore, 63.5% of all ticks were collected from cross-breed cattle, and 26.2% from the Boran, whereas the local Arssi breed carried only 10.3%. The results indicated that cattle resistant to one species of tick were also resistant to other tick species.

Abstract: Improved methods have been developed for maintaining and breeding the neotropical short-tailed fruit bat, Carollia perspicillata, in an easily-reproduced, laboratory setting. Bipartite, all-metal cages have been designed which permit efficient, non-injurious handling of the animals. Also, a fruit-based liquid diet, which is simple and inexpensive to prepare, has been formulated from readily-available canned and powdered components. When efforts were initiated to breed wild-caught animals at 3-6 months after capture, this progressed slowly in most (but not all) cages. Breeding took place more rapidly when the bats had been in captivity for 11-24 months. Most females (122/144, 84.7%) then bred within 30 days of the introduction of a stud male, and the overall conception rate was 94.3% in those females which bred. This pattern of breeding activity, evidence that this bat is a spontaneous ovulator, and observed intervals between successive breeding periods (apparently representing much or all of non-pregnant cycles) in some individuals suggest that the cycle length in many of these bats probably falls between 20 and 30 days. Analysis of the breeding data also showed that certain patterns of breeding activity were frequently associated with a failure of females to establish ongoing pregnancies. Most laboratory-bred females (69/81) that were permitted to carry their pregnancies to term did so and successfully reared their young. The laboratory-reared young have generally exhibited excellent body condition, and many have proved to be fertile. The bats were found to exhibit a post-partum oestrus, which in nearly all cases (35/36) was fertile. The interval between the discovery of a new baby and the detection of a sperm-positive vaginal aspirate varied between 3-10 days, but most frequently was 3-6 days. Females which aborted non-term fetuses also had a post-partum oestrus with similar timing. These findings indicate that the short-tailed fruit bat, which is widely abundant in the lowland tropics of the New World, can be successfully maintained under controlled conditions, in cages of modest dimensions, for research purposes.

Abstract: Two hundred and fifty Border Leicester x Merino ewes (40% heterozygous for the Booroola Fec B gene) were used in an experiment, replicated over 2 years, to examine the effects of cottonseed meal-based supplementation on lamb survival, birth, marking and weaning weight, as well as, liveweight and fleece characteristics of ewes. From 50 to 100 days of pregnancy, half of the ewes were supplemented with 80 g/head.day. The supplemented group was then split according to litter size and, until 30 days after lambing, were offered pellets at 80, 160 and 220 g/head .day, respectively, for ewes bearing single, twin and triplet (or more) lambs. Over the 2 years, ewes averaged 2.11 lambs per parturition and supplementation significantly increased lamb survival to weaning (73 v. 58%) with no interaction with litter size. Although supplementation had a positive effect on birth weight of all but twins, the effects of supplementation on survival were independent of birth weight effects. Significant effects of year, sire breed and litter size on lamb survival and birth weight were also noted. No effects of supplementation were apparent on lamb growth while ewe age, sire breed, sex and rearing rank all significantly influenced growth rates. Ewe weights, fleece weights and staple strength were significantly influenced by year, ewe age and litter size but not by supplementation. These findings indicate the benefits to lamb survival of providing a 'bypass' protein supplement to high fecundity flocks even when ewes are grazing good quality pastures.

Abstract: Fifty (ten per breed) Merino, Polwarth. Corriedale, Romney Marsh and Texel lambs were castradet at 30 days of age and raised up to weaning (ten weeks) on native pasture at the Centro de Pesquisa de Pecuaria dos Campos Sulbrasileiros (EMBRAPA), Southern (Bage, RS) region of Brazil. Following weaning, the animals were feedioted during one week and each lamb was daily fed with 200 grams of a diet containing 17% of crude protein and 75% of dry matter basin. The animals were then moved to pasture up to 225 days of age when they were slaughtered to quantify and compare in vivo and carcass tosses and morphology. Liveweight (with and without a fasting period) was influenced by genotype. However, Merino, Polwarth and Corriedale live weight were not different among themselves, but lower than Romney Marsh lambs, which by their turn, were lower than Texel animals live weight. Fasting losses was significantiy affected when compared in absolute numbers (kg), bui not percentually. Highest tosses were observed in Texel breed lambs followed by Romney Marsh, whereas Corriedale, Polwarth and Merino didnot differ among themselves. Live weight carcass yield were significantly influenced by genotype. Heavier lambs showed superior carcass yield. Texel animals showed superior in vivo and in the carcass morphology, along wilh better conformation, body condition and body and carcass capacity, as cpmpared to other breeds.

Abstract: The main purpose of this work was to compare two breeds of improved rams (Suffolk and Merino Precoce) with the local Galego Bragangano breed for the production of crossbred slaughter lambs and to evaluate which cross was more adapted for meat production from the local breed in locations in the north-east of Portugal The experiment was carried out over a 4-year period in three locations: (1) a farm with an intensive management; (2) an upland farm (400 to 600 m); and (3) a hill farm (above 800 m) Within each flock with 90 Galego Bragangano ewes, two rams of each of the sire breeds were used: Galego Bragangano, Suffolk and Merino Precoce The lambs were slaughtered at 20 and 40kg, to obtain the carcass weight range of 8 to 14kg The left sides of 151 carcasses were dissected into muscle, subcutaneous fat, intermuscular fat and bone The lambs from location 1 had the highest carcass muscle proportion and the lowest carcass intermuscular fat proportion; their differences over locations 2 and 3 were 13 and 16 g/kgfor muscle proportion and 11 and 19 g/kgfor intermuscular fat proportion, respectively The differences between breeds were relatively small and not significant However the Suffolk crosses had less kidney, knob and channel fat than the other genotypes (5 and Uglkg less than Merino crosses and Bragangano, respectively) The Suffolk crosses tended to have less body fat

Abstract: This study investigated the influences of breed and gender on the response to form deprivation and subsequent changes (recovery) when normal vision was restored Two breeds of chickens, the White Leghorn and broiler cross, were compared, as well as male and female chicks for the White Leghorn breed Normal eye growth was faster in the more rapidly growing broiler chicks; gender-differences were not as great as breed-differences although male White Leghorns ultimately became heavier and showed slightly greater normal eye growth than females While both breeds showed high myopia and axial elongation in response to form deprivation, they differed significantly in the magnitude of their response, with White Leghorns showing more myopia and greater axial elongation and also recovering more slowly Responses to form deprivation were similar for both genders, with respect to both the amount of myopia and axial elongation produced, although the female chicks recovered faster Together these observations indicate that, although the overall pattern of response of form deprivation is consistent across both breed and gender, related quantitative differences in responses can be expected and need to be taken into account in experimental design and cross-study comparisons