Model calculations on the economic efficiency of sheep production

The answers to the questionnaire by the Commission on Sheep and Goat Production show quite large differences in the price relationships, particularly between meat and wool.It is at first shown from model calculations, how the optimum duration of using the ewes changes with a change of the relationship between mutton price and lamb meat price. In all cases, in which mutton is very cheap in comparison with lamb meat, a longer utility period is generally more efficient than a shorter one and vice versa (Fig.1).The relative importance of lamb carcases of different weight, in relationship to varying concentrate costs shows according to the conditions given in the model that when the price per kg meat is equal regardless of the carcase weight, that a 25 kg carcase is more efficient than producing a 20 kg carcase. On the other hand, if the meat of a 25 kg carcase is only valued at 90% of that of the 20 kg carcase, then the 20 kg carcase is preferable (Fig.2).Using the formula formerly developed for meat production and now expanded for other purposes 64 000 model calculations were made. The change of efficiency through changing of wool price, through increasing the level of fertility, through altering of working time and cost per hour as well as other factors, was illustrated by means of a few examples (Fig.3 and 4).The results of special calculations of efficiency should not be generalised even through they could be of valuable help in breeding, management techniques and making economic decisions in business under given conditions.     

Genetic, environmental and interaction effects on lifetime production efficiency of crossbred ewes

A total of 399 crossbred ewes born in 2 yr were maintained either on irrigated or dryland hill pastures. The ewes were sired by North Country Cheviot, Dorset, Finnsheep or Romney rams mated to Suffolk or Columbia-type ewes. The crossbred ewes were mated to Hampshire rams throughout the study and had the opportunity for either 4 or 5 yr of production. Annual feed cost was calculated based upon estimated annual metabolizable energy (ME) requirements for maintenance, ewe growth, pregnancy and lactation. Income from weaned feeder lambs and from orphan lambs sold shortly after birth, feed cost and net revenue were analyzed during each ewe's first production year, as well as for the entire period of the experiment. Crossbred group significantly affected income from lambs produced, feed cost and net revenue for the ewes' first production year. Crossbred group and crossbred group X management system interactions generally influenced lifetime income from lambs produced and from orphans sold, gross income, total cost and net revenue per ewe. Finnsheep X Suffolk ewes performed best on irrigated pastures but were below average for lifetime net revenue on hill pastures. Finnsheep X Columbia ewes performed best on hill pastures and, with Dorset X Suffolk and Dorset X Columbia ewes, were well above average for lifetime net revenue on irrigated pastures as well. Suffolk crossbreds consistently performed better on irrigated than on hill pastures. While most ewes with Columbia-type inheritance were more efficient on hill than on irrigated pastures, this result was not always consistent.     

饲养模式对绵羊冷季生产效益的影响

在肃南裕固族自治县选择草场类型一致,绵羊(Ovisaries sp.)体况相近的3个牧户分别采取暖棚全舍饲(试验组Ⅰ),放牧+补饲(试验组Ⅱ)以及全放牧(对照组)3种饲养方式,通过测定整个繁殖周期绵羊体质量变化、母羊繁殖率和羔羊成活率指标,比较不同饲养模式对绵羊生产效益的影响.结果表明,3种饲养模式下越冬母羊体质量损失...     

Phenotypic relationships among early life traits and lifetime ewe production efficiency

In least-squares analyses of variance, 10 ewe lamb traits were used, singly and in various combinations, to predict lifetime production efficiency. Ewes belonged to eight crossbred groups and were raised on two management systems for either 4 or 5 yr of production. Lifetime production efficiency components were total feed and ewe ownership cost, gross income and net revenue. A ewe lamb's type of birth, actual and adjusted weaning weight (WWt and AWWt), postweaning weight (PWWt) and first year gross income (FGROS) were significantly phenotypically related to one or more components of lifetime production efficiency. While triplets were better than either of the other two birth types, single-born ewes were better than twin-born ewes for lifetime production efficiency. Any of the three ewe lamb weights (AWWt, WWt or PWWt) appeared to be an accurate estimator of lifetime production efficiency. The effect of first year productivity was largely a part-whole relationship with lifetime production because the regression coefficients of subsequent lifetime production efficiency (not including first year production) on first year productivity were near zero. Postweaning average daily gain, ewe age at first estrus and date of first lambing (at approximately 12 mo of age) did not have significant relationships with lifetime production efficiency. When type of birth, date of birth, weaning weight and first year gross income were analyzed simultaneously, weaning weight and FGROS had the greatest effect on lifetime production efficiency. When AWWt and type of birth were considered simultaneously, both had significant relationships with lifetime production efficiency.     

Divergent selection of chickens for antibody production to sheep erythrocytes: age effect in parental lines and their crosses

Age dependency of antibody response to sheep red blood cell (SRBC) antigen was measured in lines of chickens divergently selected for this trait and in reciprocal crosses between them. At 7 days of age, there were differences among populations for frequency of responders to SRBC antigen. This qualitative pattern persisted in the quantitative context of the antibody titers of those who responded, demonstrating genetic differences in both the event and subsequent levels of antibody. Although chickens from the high line had significantly higher titers than those from the low line and cross populations, all reached serological maturity by 14 days of age. From this age, high-line chickens had higher bursa and spleen weights and lower thymus weights relative to body weight than those from the low line: relative to body weight, spleen and bursa weights increased at a faster rate through 19 and 25 days of age, respectively, and then plateaued. In contrast, there was a progressive increase in thymus weight relative to body weight through 40 days of age.     

无角美利奴细毛羊选育研究

自1996年以来，以强毛型澳洲美利奴无角系公羊为父本，康拜克、邦德等品种母羊为母本进行杂交育种，培育无角美利奴细毛羊。几年来共培育出无角美利奴细毛羊16987只，存栏5250只，核心群羊达3250只，其中特一级羊占83．18％；成年公、母羊剪毛后体重分别为107.9kg和57.48kg，毛长分别为12.35cm和11．02cm，净毛量分别为10.91kg和5.2kg。选育的无角美利奴细毛羊具有体格大、毛长、产毛量高、产肉多、净化率高和羊毛品质好等特点，各项生产性能和体型外貌接近澳洲美利奴羊水平。应用无角美利奴细毛羊改良低产细毛羊，取得了明显效果。     

呼伦贝尔短尾羊产前补饲精喂对家畜个体特征及生产效益的影响

在内蒙古草原牧区,冬季对绵羊补饲精喂的研究具有重要的意义。为研究产羔前对母畜舍饲精料后,呼伦贝尔短尾羊体重、体尺及经济效益的变化,本研究选取60对待产的呼伦贝尔短尾母绵羊作为试验对象,在母畜产羔前一个月,试验组母畜舍饲精料,对照组仅补饲干草,分析100日龄内家畜体重、体尺及经济效益变化。利用方差及偏最小二乘回归法,分析产前补饲对家畜个体、生产效益的影响及影响家畜体重的主要体尺权重,结果显示,100 d时间段内,母畜体重呈先减少后增加的趋势;仔畜出生后一个月左右的时间段,试验组仔畜的胸围、胸宽、体高、胸深、体长和体斜长显著高于对照组(P<0.05)。影响呼伦贝尔短尾羊体重的主要体尺指标为:胸围、胸宽、体高和胸深,影响权重达到50%以上。补饲使得仔畜的成活率、出售价格显著高于未进行补饲的对照组(P<0.05)。通过补饲母畜不仅可以影响仔畜体重和体尺指标,而且对提高仔畜成活率和经济效益具有重要的作用,这为今后后备母羊的选育、家畜的精准淘汰提供了理论基础。     

Reproductive efficiency of Iceland sheep

Iceland sheep are found to be relatively early maturing and the level of reproductive efficiency in the flock is raised by breeding from ewe lambs. Ram lambs are normally used for mating. Ewe prolificacy is progressively being increased by genetic selection for a higher lambing rate in conjunction with improvements in feeding. Lamb mortality is kept at a relatively low level by close supervision at lambing and disease control.     

肉羊生产转型升级提质增效的“程明模式”

铜川市程明牧业股份有限公司(以下简称“程明牧业”)前身是一位残疾青年于2012年与他人合办的羊场。由于该羊场圈舍简陋、品种繁杂低劣、经营管理粗放而亏损,2013年合伙人撤资。2014年,陕西省畜牧技术推广总站联合铜川市畜牧技术推广站等单位,按照“深入实际搞调研、理清思路作指导、技术支撑提水平、抓好样板做示范”的工作思路助残抓点。在有关部门和单位的支持下,该羊场现已发展为以肉羊养殖为主,集饲草饲料经营、肉羊屠宰加工、品牌销售为一体,融合农业种植、休闲观光、科普文化和餐饮服务等产业的综合性企业,成功走出了一条肉羊转型升级提质增效的路子。     

Genetic relationships between length of productive life and lifetime production efficiency in a commercial swine herd in Northern Thailand

Genetic parameters and trends for length of productive life (LPL), lifetime number of piglets born alive per year (LBAY), lifetime number of piglets weaned per year (LPWY), lifetime litter birth weight per year (LBWY) and lifetime litter weaning weight per year (LWWY) were estimated using phenotypic records of 3085 sows collected from 1989 to 2013 in a commercial swine farm in Northern Thailand. The five‐trait animal model included the fixed effects of first farrowing year‐season, breed group and age at first farrowing. Random effects were animal and residual. Heritability estimates ranged from 0.04 ± 0.02 for LBWY to 0.17 ± 0.04 for LPL. Genetic correlations ranged from 0.66 ± 0.14 between LPL and LBAY to 0.95 ± 0.02 between LPWY and LWWY. Spearman rank correlations among estimated breeding values for LPL and lifetime production efficiency traits tended to be higher for boars than for sows. Sire genetic trends were negative and significant for all traits, except for LPWY. Dam genetic trends were positive and significant for all traits. Sow genetic trends were mostly positive and significant only for LPWY and LBWY. Improvement of LPL and lifetime production efficiency traits will require these traits to be included in the selection indexes used to choose replacement boars and gilts in this population.     

Case study: The effect of inbreeding on the production and reproduction traits in the Elsenburg Dormer sheep stud

Data of the Elsenburg Dormer sheep stud, which was kept closed since inception, were collected over a period of 62 years (1941–2002). The breed is a composite, resulting from a cross of Dorset Horn rams with South African Mutton Merino ewes. These data were analysed to quantify the increase in actual level of inbreeding and to investigate the effect of inbreeding on phenotypic values, genetic parameters and estimated breeding values. After editing 11954 pedigree, 11721 birth weight (BW) and survival, 9205 weaning weight (WW) and 7504 reproduction records were available for analysis. The mean level of inbreeding (F) of all animals over all years was 16%; 14% for dams and 16% for sires. Mean, minimum and maximum F for the lambs in 1997 (when 3 rams from outside were introduced) were 22%, 21% and 24% respectively. Estimates of inbreeding depression for individual inbreeding of 1% were − 0.006 kg for birth and − 0.093 kg for weaning weight respectively. These were the only estimates that were significantly (P < 0.01) different from zero. No significant effects of inbreeding on the other traits were found. There were virtually no differences in the genetic parameters estimated when fitting the two models (inclusion or exclusion of inbreeding coefficients as covariates). Estimates of the phenotypic variance differed slightly for WW between the two models. Ranking of animals were studied for weaning weight when the two models were considered. The high correlation coefficients (0.990) indicate that the use of inbreeding coefficients did not cause important changes in ranking of animals and sires for WW. It was concluded that slow inbreeding (rate of inbreeding of approximately 1.53% per generation over 19 generations) allows natural selection to operate and to remove the less fit animals. At any given mean level of F, less inbreeding depression would then be expected among the individuals who accumulated the inbreeding over a larger number of generations. Nevertheless, inbreeding coefficients should be considered when mating decisions are made, to limit the possible deleterious effects of inbreeding on productive and reproductive traits and to detect animals “resilient to” higher levels of inbreeding.     

Influence of selenium on antibody production in sheep

Three experiments were carried out, using sheep fed a marginally low selenium diet, to study the effect of selenium supplementation on the antibody response to tetanus toxoid and on the serum IgG concentration. Six groups of three six-month-old lambs were fed a basal diet containing 0.13 mg Se kg-1 supplemented with either 0.1, 0.5 or 1.0 mg Se kg-1, as sodium selenite or as selenomethionine. These animals generally showed enhanced antibody response to tetanus toxoid, parainfluenza-3 virus and Corynebacterium pseudotuberculosis, and their total serum IgG concentrations were higher than in unsupplemented control animals although few responses were statistically significant. In two field studies significantly higher titres to tetanus toxoid were detected in ewes injected with 100 mg selenium as barium selenate, although no influence on serum IgG concentrations was detected. Lambs from selenium supplemented ewes had significantly higher titres to tetanus toxoid than lambs from ewes in the control group. Dietary vitamin E supplementation had a similar effect on the antibody response to tetanus toxoid in ewes, though no additive effect was seen when vitamin E was given together with selenium.