早期断奶对羔羊生长发育的影响

将120只10～15 日龄的德国美利奴羊(♂)×小尾寒羊(♀)杂交一代羔羊随机分为Ⅰ、Ⅱ、Ⅲ、Ⅳ组,Ⅰ组于35 日龄断奶、Ⅱ组于45日龄断奶、Ⅲ组于60 日龄断奶、Ⅳ组于90日龄断奶.结果表明:60 d体重4组间无显著差异(P>O.05);90 d体重,Ⅱ、Ⅲ、Ⅳ组极显著(P(0.01)高于Ⅰ组,Ⅱ、Ⅲ、Ⅳ组间差异不显著(P>O.05).30～60日龄日增重,Ⅱ、Ⅲ、Ⅳ组极显著高于Ⅰ组(PO.05).45日龄断奶,羔羊体质健壮,抗病能力较强,综合效益高,为最佳断奶时间.     

Evaluation of Columbia, USMARC-Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: I. Ewe productivity and crossbred lamb survival and preweaning growth

A 3-yr study was conducted to comprehensively evaluate columbia, suffolk, usmarc-composite (composite), and texel breeds as terminal sires in an extensive rangeland production system. The objective was to estimate breed-of-ram effects on ewe fertility, prolificacy, and dystocia, and sire breed effects on lamb survival and growth until weaning at approximately 132 d of age. Data were from 22 columbia, 22 composite, 21 suffolk, and 17 texel rams with 957 exposures to 574 adult rambouillet ewes (3- to 7-yr-old at lambing), 908 lambings, and 1,834 lambs. Ram breed did not affect ewe fertility (mean = 94.9%; p = 0.73), total number born per ewe lambing (mean = 2.02 lambs; p = 0.20), number born alive per ewe lambing (mean = 1.90 lambs; p = 0.24), or number weaned per ewe lambing (mean = 1.45 lambs, p = 0.94). Dystocia rates were different (p = 0.01) for ewes mated to columbia (12.2%), composite (13.5%), suffolk (25.7%), and texel rams (31.9%) during 1 yr of the study, but differences among ram breeds were not repeatable (p ≥ 0.38) during the other 2 yr. Suffolk-sired lambs were heavier (p ≥ 0.02) at birth (5.5 kg) and weaning (40.3 kg) than lambs sired by the other breeds, which did not differ (p ≥ 0.34) for birth weight (mean = 5.3 kg). Texel-sired lambs (37.4 kg) were lighter (p ≥ 0.02) at weaning than columbia- (38.8 kg) and composite-sired (38.4 kg) lambs, which did not differ (p = 0.40) for weaning weight. Sire breed effect approached significance (p = 0.06) for lamb survival to weaning; estimated survival probabilities were 0.87 (columbia), 0.89 (composite), 0.93 (suffolk), and 0.86 (texel) for lambs reared by their birth dam. Interaction between sire breeds and birth weight affected (p < 0.001) lamb survival and revealed that lightweight columbia- and suffolk-sired lambs had a greater risk of death than lightweight lambs sired by composite and texel rams, but risk of death did not increase substantially for heavyweight lambs from any of the breeds. When mated to adult rambouillet ewes in an extensive rangeland production system, the use of suffolk rams is warranted to improve preweaning growth of market lambs and is not predicted to affect ewe fertility, ewe prolificacy, dystocia, or lamb survival compared with the other sire breeds we tested.     

Genetic parameters for early lamb survival and growth in Scottish Blackface sheep

The objectives of this study were 1) to estimate the heritability of lamb survival and growth in the Scottish Blackface breed; 2) to examine the relationship between lamb survival and live BW; and 3) to investigate the possibility of using lamb survival in a breeding program for this breed. The data used for the analyses contained information about survival and live BW at different ages on 4,459 animals. The records were collected from 1988 to 2003 in a Scottish Blackface flock. Live BW was recorded every 4 wk from birth to 24 wk. Survival was defined either by perinatal or postnatal mortality (up to weaning at 12 wk), or as cumulative survival to 1, 4, 8, and 12 wk. The pedigree file comprised 1,416 dams and 178 sires. A sire model was used to estimate genetic parameters for binary survival traits. Heritabilities of BW traits, and phenotypic and genetic correlations between BW and between survival and BW were estimated by fitting an animal model. Further, correlations of survival with live BW were estimated by using a Markov chain Monte Carlo threshold model, implemented by Gibbs sampling. The heritability estimates for cumulative lamb survival declined from birth onward (from 0.33 to 0.08), and postnatal survival had a heritability of 0.01. The direct and maternal heritabilities for BW traits ranged from 0.08 to 0.26 and from 0.06 to 0.21, respectively, whereas the maternal environmental component was between 0.04 and 0.16. The genetic correlations between BW traits at different ages were high. The genetic and phenotypic correlations between survival and BW were always positive (ranging from 0.04 to 0.54), so there was no antagonism between these traits. Therefore, it is possible to simultaneously improve both survival and live BW in a breeding program for this breed.     

Survival analysis of lamb mortality in a terminal sire composite population

Records of mortality during the first year of life of 8,642 lambs from a composite population at the U.S. Meat Animal Research Center were studied using survival and logistic analyses. The traditional logistic approach analyzes the binary response of whether or not a lamb survived until a particular time point, thus disregarding information on the actual age at death. Survival analysis offers an alternative way to study mortality, wherein the response variable studied is the precise age at death while accounting for possible record censoring. Lamb mortality was studied across five periods based on management practices: birth to weaning, birth to 120 d of age, birth to 365 d of age, weaning to 365 d of age, and 120 to 365 d of age. Explanatory variables included in the models were sex, type of birth, age of dam, and whether or not a lamb was raised in a nursery. The survival analysis was implemented using Weibull and Cox proportional hazards models with sire as random effect. The logistic approach evaluated sire, animal, and maternal effects models. Lambs culled during any period were treated as censored in the survival analyses and were assumed alive in the logistic analyses. Similar estimates of the explanatory variables were obtained from the survival and logistic analyses, but the survival analyses had lower standard errors than the logistic analyses, suggesting a slight superiority of the former approach. Heritability estimates were generally consistent across all periods ranging from 0.15 to 0.21 in the Weibull model, 0.12 to 0.20 in the Cox model, 0.08 to 0.11 in the logistic sire model, 0.04 to 0.05 in the logistic animal model, and 0.03 to 0.07 in the maternal effects logistic model. Maternal effects were important in the early stages of lamb life, but the maternal heritability was less than 0.07 in all the stages studied with a negative correlation (-0.86 to -0.61) between direct and maternal effects. The estimates of additive genetic variance indicate that the use of survival analysis estimates in breeding schemes could allow for effective selection against mortality, thereby improving sheep productivity, welfare, and profitability.     

Competing risks analysis of lamb mortality in a terminal sire composite population

Mortality records from birth to weaning of 8,301 lambs from a composite population at the U.S. Meat Animal Research Center were analyzed using a competing risks model. The advantage of the competing risks model over traditional survival analyses is that different hazards of mortality can be assigned to different causes, such as disease, dystocia, and starvation. In this study, specific causes of mortality were grouped into dam-related (DAMR; e.g., dystocia and starvation), pneumonia (PNEU), disease (DIS; excluding pneumonia), and other (OTHER) categories. The hazard of mortality was analyzed using a competing risk approach, where each mortality category was assumed to be independent. Continuous- and discrete-time survival analyses were implemented using sire, animal, and maternal effects mixed models. The continuous-time survival analysis used the Weibull model to describe the hazard of mortality for each category of mortality. Under the discrete-time survival analysis, a complementary log-log link function was used to analyze animal-time data sets using weekly intervals for each category of mortality. Explanatory variables were sex, type of birth, contemporary group, and age of dam. The significant influences of type of birth and age of dam effects were consistent across category of mortality, and the sex effect was significant for all categories except the OTHER category. Estimates of variance components indicated strong maternal effects for all categories except for PNEU. Estimates of additive genetic heritabilities from the discrete maternal effects models were 0.08+/-0.04, 0.09+/-0.18, 0.16+/-0.12, 0.19+/-0.09, and 0.14+/-0.10 for OVERALL (all causes combined), DIS, DAMR, PNEU, and OTHER categories, respectively. Ignoring the cause of the defining event in mortality and longevity studies may hide important genetic differences. Therefore, the effectiveness of breeding programs relying on models that ignore multiple causes of an event in time-to-event data, such as mortality and longevity, could be affected.     

Investigation in early growth traits, litter size, and lamb survival in two Iranian fat-tailed sheep breeds

In the present study, 1,635 lambing records of Ghezel (n?=?766) and Mehraban (n?=?869) breeds were used to evaluate the early growth traits, litter size, and lamb survival in sheep reared in Fars Province, southern Iran, during a 5-year-long period. The least squares means (± SE) of lamb birth weight for Ghezel were 5.27 (±0.22), 5.02 (±0.22), and 3.98 (±0.23) kg for single males, single females, and twin lambs, respectively; whereas, the corresponding values for Mehraban were 4.39 (±0.18), 4.18 (±0.18), and 3.50 (±0.19) kg. The least squares means of pre-weaning lamb growth (gram per day) for Ghezel were 239 (±15), 218 (±15), and 181 (±16) for single males, single females, and twin lambs, respectively, and the corresponding values for Mehraban were 204 (±12), 187 (±12), and 156 (±13). Lambs from 2 year old ewes or younger were on average lighter at birth and at weaning and had a lower average daily gain than those from older ewes (P?<?0.05). The percentage of twin births increased from 1.1 and 1.3 % for ewes aged ≤ 2 years to 19 and 12 % for those aged ≥ 6 years old in Ghezel and Mehraban, respectively (P?<?0.05). The mean pre-weaning lamb mortality was 7.1 and 4.1 % for Ghezel and Mehraban, respectively.     

Discrete time survival analysis of lamb mortality in a terminal sire composite population

Mortality records of 8,642 lambs from a composite population at the U.S. Meat Animal Research Center during the first year of life were studied using discrete survival analyses. Lamb mortality was studied across periods from birth to weaning, birth to 365 d of age, and weaning to 365 d of age. Animal-time data sets were created for each period using different time intervals: daily, weekly, fortnightly, and monthly. Each data set was analyzed using logistic and complementary log-log sire, animal, and maternal effects models. Explanatory variables included in the models were duration of time interval, sex, type of birth, contemporary group, age of dam, and type of upbringing (nursery or not). Similar estimates of explanatory variables were obtained within the same period across models and different time intervals. Heritability estimates from the complementary log-log models were greater than those from the comparable logistic models because of the difference in variance of the respective link functions. Heritability estimates from the complementary log-log sire model ranged from 0.13 to 0.21 for all periods. These estimates were greater than the complementary log-log animal model estimates that ranged from 0.04 to 0.12. Maternal effects were important early in life, with the maternal heritability slightly greater than the direct additive heritability. Negative correlations (-0.72 to -0.65) between direct additive and maternal effects was estimated. The similarity of results among survival analysis methods demonstrates that the discrete methodology is a viable alternative to estimate variance components in livestock survival data.     

Magnesium supplementation of lactating ewes and lamb growth

Ewes rearing twin lambs on a restricted ration of irrigated pasture were either supplemented daily with 12.5 mg magnesium chloride or not. Serum magnesium levels measured 24 hours after the previous day's dose did not differ between treatments. They averaged 0.74 mmol/l during the period of supplementation with 36% of values below 0.7 mmol/l, the lower limit of the "normal" range. Milk consumption by and liveweight gains of lambs were not increased by magnesium supplementation indicating that ewe magnesium levels below 0.7 mmol/l serum did not limit production in this instance.     

羔羊血清促细胞生长效果的研究

为研究羔羊血清促细胞生长的效果,用羔羊血清以及羔羊与新生牛混合血清来培养VERO、BHK-21细胞,同时培养SP2/0-Ag14细胞并进行计数。结果表明：羔羊血清促细胞生长效应明显低于新生牛血清,但是与牛血清以不同比例混合后,促细胞生长效应有明显的提高,比例在4∶6和5∶5时,促细胞生长能力与牛血清接近。因此,在细胞培养过程中,把羔羊血清和新生牛血清按1∶1混合使用,既可降低成本,又具有良好的促细胞生长效果,使羔羊血清得到了充分利用,并产生一定的经济效益和社会效益。     

两种不同营养水平的代乳粉对羔羊生长性能的影响

试验选用18只10日龄公羔，随即分成A、B、C三组，A组哺喂1号（低营养水平）代乳粉，B组哺喂2号（高营养水平）代乳粉，C组随母羊自然哺乳，每隔10d测定一次体重、体尺，进行了60d的饲养试验，结果表明：30日龄前，特别是10～20日龄阶段，自然哺乳组日增重达到154g／d，而代乳粉组平均日增重仅仅76．9g／d，试验组与对照组差异极显著（P〈0．01）；20日龄时，A、B、C三组体高增加分别为2．4％、6．50％、7．36％，A、B两组分别与C组差异极显著（P〈0．01）；体长A、B两组与C组差异显著（P〈0．05）：但随着日龄的增加，消化道逐渐健全，羔羊越来越习惯于吸允代乳粉，消化吸收能力加强，尤其到试验后期（41—60d），B组表现明显的生长优势，不同日龄体重、阶段平均日增重、体高、体长、胸围、管围都明显高于A组和C组。     

杜泊绵羊羔羊生长发育规律的研究

杜泊羔羊体形外貌一致 ,黑头白身躯 ,肉用体型典型。初生重 :公羔 5 3kg± 0 8kg ,母羔 4 5kg± 0 9kg ;3月龄体重 :公羔 3 7 9kg± 5 3kg ,母羔 3 3 3kg± 4 4kg ;0～ 3月龄平均日增重 3 5 1g± 71g ,其中公羔 3 85g± 74g ,母羔 3 3 3g± 64g。饲料利用率高 ,哺乳期只均日耗颗粒饲料 (含 2 4%花生秧粉 ) 5 2 1g ,料重比为 1 8∶1(母乳除外 ) ;抗寒耐热 ,抗病力强 ,适应性好 ,易管理     

Prevalence of Anaplasma phagocytophilum infection and effect on lamb growth

Background

A major challenge in sheep farming during the grazing season along the coast of south-western Norway is tick-borne fever (TBF) caused by the bacteria Anaplasma phagocytophilum that is transmitted by the tick Ixodes ricinus.

Methods

A study was carried out in 2007 and 2008 to examine the prevalence of A. phagocytophilum infection and effect on weaning weight in lambs. The study included 1208 lambs from farms in Sunndal Ram Circle in Møre and Romsdal County in Mid-Norway, where ticks are frequently observed. All lambs were blood sampled and serum was analyzed by an indirect fluorescent antibody assay (IFA) to determine an antibody status (positive or negative) to A. phagocytophilum infection. Weight and weight gain and possible effect of infection were analyzed using ANOVA and the MIXED procedure in SAS.

Results

The overall prevalence of infection with A. phagocytophilum was 55%. A lower weaning weight of 3% (1.34 kg, p < 0.01) was estimated in lambs seropositive to an A. phagocytophilum infection compared to seronegative lambs at an average age of 137 days.

Conclusions

The results show that A. phagocytophilum infection has an effect on lamb weight gain. The study also support previous findings that A. phagocytophilum infection is widespread in areas where ticks are prevalent, even in flocks treated prophylactic with acaricides.     

白萨福克羔羊和特克塞尔羔羊早期生长发育的比较研究

试验对白萨福克羊(White Suffolk)和特克塞尔羊(Texel)两个肉羊品种的羔羊在6月龄以前的生长发育进行了比较研究。结果表明:白萨福克羔羊和特克塞尔羔羊初生重大,除白萨福克母羔外,其余羔羊初生重都在5 kg以上,其中白萨福克公羔的初生重最大;4月龄时,白萨福克公羔体重达到32.88 kg,显著高于特克塞尔公羔(P<0.05),极显著地高于特克塞尔母羔(P<0.01);6月龄时白萨福克公羔体重达到42.60 kg。白萨福克羔羊2月龄时的绝对生长速度最大,公羔日增重达到256.15 g,母羔达到236.67 g;特克塞尔羊从出生到1月龄,绝对生长和相对生长比白萨福克羊要高一些,但是白萨福克羊保持快速生长发育的持续期较特克塞尔羊相对较长。白萨福克羔羊从母乳到饲草饲料过渡较好,断奶后适应性要好于特克塞尔羔羊,从4月龄到6月龄的体重、体尺高于特克塞尔羔羊。在整个测定阶段,白萨福克公羔和母羔的体躯均比特克塞尔公羔和母羔的体躯长,白萨福克公羔体高比特克塞尔公羔的体高要高。     

维生素E对羔羊成活率和生产性能的影响

维生素Ｅ是所有具有α -生育酚功能的母育酚和生育三烯醇衍生物的总称。放牧到春天青草茂盛草场上的母羊 ,一般含有高浓度的血清维生素Ｅ。相比之下 ,饲喂贮藏干草或休牧期的母羊 ,通常含有较低的血清维生素Ｅ浓度。母羊血清维生素Ｅ水平产前 7ｄ可降低约 50 % ,直到产后 2 0～ 3 0ｄ才会恢复至正常水平。因此有理由推测休牧期或喂给收割饲料的怀孕绵羊在冬末春初产羔之前 ,为提高羔羊生产力需补充维生素Ｅ。脂肪组织是机体储存维生素Ｅ的主要部位 (Ｐｕｌｓ ,1 994)。然而维生素Ｅ不可能以合理的浓度被储存于机体内 (Ｒａｍ ｍｅｌｌ,1 983…     

Interrelationship between late gestational ewe factor and early life lamb factors in semi-arid tropical region

Tropical Animal Health and Production - The limitation in feed availability in the semi-arid region during the lean period can result in a variation of the body condition, body weight of pregnant...     

Effect of system of lamb rearing and season on early post‐partum fertility of ewes and growth performance of lambs in Katahdin sheep

The effect of season (S), lamb rearing system (RT) and grain supplementation (GS) on post‐partum fertility in Katahdin ewes and growth in Katahdin lambs was evaluated. Katahdin ewes were bred to lamb in fall (n = 36) or spring (n = 56) and at approximately 2.5 months post‐partum were randomly assigned to be permanently separated or to continue to suckle their lambs for an additional 3 months. All ewes were joined with rams following treatment to synchronize oestrus. Weaned (W, n = 84) and continuously suckled lambs (CSK, n = 88) were fed forage only (n = 84; hay and pasture for fall‐ and spring‐born lambs respectively) or were supplemented (n = 88; 18% crude protein ration ad libitum) and all weighed biweekly. Ewes rebred in the fall had a shorter ram introduction to lambing interval (p < 0.05), higher prolificacy (p = 0.001) and higher lambing rates (p = 0.02); however, the proportion of ewes lambing was not affected by season. The first service lambing rate was lower in ewes continuously suckling lambs in the spring, but not in the fall breeding season (S × RT, p = 0.03). Lambs that continuously suckled their dams and were supplemented grew quicker and gained more (p < 0.001) than their weaned and unsupplemented counterparts. The effect of CSK on growth rate of lambs was greater in the spring (RT × S; p = 0.05), and the effect of supplementation on growth rate of lambs was greater in the fall (GS × S; p < 0.0001). In conclusion, Katahdin lambs achieved higher weight gains from continuous suckling and grain supplementation. Moreover, Katahdin ewes are capable of early rebreeding post‐partum while suckling their lambs, which makes them suited for use in accelerated lambing programmes.