共查询到20条相似文献，搜索用时 15 毫秒
1.
Functional traits are an important aspect of long‐term breeding strategies for dairy cattle. In this regard, it is necessary to develop simple methods for estimating the economic value of herd life. In this study, the economic daily value of herd life was estimated when survival rate varied between ?0.05 and 0.05 from the basal survival rate. The extension days per survival rate were 26.5 days in Hokkaido and 20.3 days in other regions. The increases in values of annual income per day of herd life were 95.18 yen in Hokkaido and 101.80 yen in other regions. The relative economic weights of milk yield to herd life per genetic standard deviation were 0.668 in Hokkaido and 1.03 in other regions. Estimated increments in yearly profits based on young sire selection for herd life were 963 yen in Hokkaido and 1,030 yen in other regions. The estimated increments in annual profits based on young sire selection for milk yield were 1,268 yen in Hokkaido and 2,097 yen in other regions. Given that economic value was linearly correlated with herd‐life length, the linear regression coefficients between these factors could be used to estimate the economic value of herd‐life length. 相似文献
2.
The study describes the profiles of culled cows in order to assess the possible contribution to economic losses due to health disorders. Data regarding dates of birth, final calving and culling, parity at culling, milk yield at the two first test-days of the final lactation and reason(s) for culling were collected in a 5-year survey, carried out from 1989 to 1994 in 84 commercial Holstein farms in western France. Polytomous logistic regression was used to assess the relationship between parity, calving-to-culling interval, milk yield and eight groups of primary culling reasons (i.e. udder disorders; infertility or reproductive disorders; lameness or foot/leg defects; emergency culling reasons; other health disorders; low milk yield; sales for dairy purpose; and other voluntary culling reasons). Out of a total of 5133 culled cows, the proportions of culls, for each of these groups of reasons, were 12.4, 28.4, 2.7, 3.9, 4.6, 16.7, 5.9, and 25.4%, respectively. Cows culled for udder disorders left the herd earlier in lactation and were more frequently at parities 4–6 than cows culled for voluntary reasons. In contrast, cows culled for infertility were younger and culled later within lactation. They were also higher yielding cows than those culled for other reasons. Cows culled for lameness were similar to those of the voluntarily culling group. Cows culled for emergency reasons were more frequently younger cows in early lactation. Cows culled for other health disorders left the herd early in lactation, but at a higher parity than the voluntarily culled cows. These results suggest that most of the culls related to health could be contributing to economic loss. However, special priority should be given to reduce culling for reproductive problems, which is the most costly exit reason. 相似文献
3.
The effects of 15 diseases, pregnancy status and milk yield on culling were studied in 39 727 Finnish Ayrshire cows that calved in 1993 and were followed until culling or next calving. Survival analysis, using the Cox proportional hazards model, was performed with diseases, pregnancy status and milk yield as time-dependent covariates. Effects of parity, calving season and herd were also accounted for.
Pregnancy status was the single most influential factor affecting culling decisions, followed by milk yield. Several diseases also had a significant effect on culling, the most influential ones being mastitis, lameness, teat injuries, and milk fever. The effects of all of these factors varied according to the stage of lactation.
Milk yield had a significant effect on culling decisions, depending on the stage of lactation. At the beginning of lactation, milk production did not have any effect on culling decisions, but later on, the highest producers were at the lowest risk of being culled and the lowest producers had the highest risk. Adjusting for milk yield modified the effects of parity, most diseases and also pregnancy status on culling. Effects of parity increased after including milk yield in the model, indicating that milk yield and parity are interrelated in their effects on culling. The effects of pregnancy status also increased towards the end of lactation when milk yield was accounted for in the model. The effects of mastitis, teat injuries and lameness decreased after adjusting for milk production. These diseases lower milk yield and thus, part of their effect on culling was mediated through milk production. The effects of anestrus and ovarian cysts were mainly modified by pregnancy status, but not by milk yield. The effects of milk fever on culling increased at the beginning of lactation after including milk yield in the model. This suggests that even though cows with milk fever tend to be higher producers, it is the disease as such that triggers the culling decision early in the lactation. The changes in the effects of other diseases after adjusting for milk yield varied, depending on the disease and the stage of lactation. 相似文献
4.
Associations between rearing conditions and the risk of culling in dairy cows were studied by survival analysis. Data were collected from 1039 Swedish Red cows, 1029 Swedish Holsteins, and 56 cows of other milk or cross-breeds, representing all female animals born in 109 Swedish herds during 1998. Length of productive life was defined as the number of days from 1st calving to culling. The applied Weibull proportional hazards model included time-independent effects of breed, housing from 3 to 7 months of age, number of housing changes before calving, grazing before 1st calving, herd median age at 1st calving, age at 1st calving, cow housing, herd lactational incidence risk of veterinary-reported clinical mastitis, and the random effect of herd. Time-dependent effects were year, month, the interaction year by month, parity, number of breedings, pregnancy status, the interaction parity by pregnancy status, herd mean milk-production level, relative milk yield within breed-parity, and veterinary-reported clinical mastitis. The lactation was divided into six stages in which pregnancy status was assumed to be known by the farmer and culling could occur. Median productive life time in culled cows was 780 d and 14% of the records were censored due to terminated data collection. An individual calving age of 28.2–30.9 months was associated with the highest culling risk, 1.2-fold higher than calving at ≤25.3 months, whereas the risk decreased almost linearly with a higher herd median age at 1st calving. Housing in slatted pens with >7 calves from 3 to 7 months was associated with a 1.7-fold increase in risk, relative to litter pens. If a cow had changed housing system 4 times before 1st calving it increased the risk of culling 1.4 times, relative to two housing changes. These results show that rearing factors affect the productive life time of dairy cows in Swedish family operations. 相似文献
5.
Survival analysis of factors affecting culling early in the productive life of Holstein-Friesian cattle in Kenya 总被引：1，自引：0，他引：1
Holstein-Friesian cattle raised in tropical environments pose a challenge due to genotype by environment interactions which may lead to higher rates of involuntary culling and reduce profit margins obtainable. This study assessed factors influencing culling within the first three parities of Holstein-Friesian cattle raised on four large-scale farms in Kenya using a Cox proportional hazard model. Differences in length of productive life (LPL) due to differences in area of origin of sires were also assessed in an attempt to determine possible adaptations by specific genotypes to the Kenyan environment. Environmental effects of herd, year-season, parity, sire area of origin, milk yield class and stage of lactation all significantly affected LPL. Daughters of sires born in Kenya tended to have a higher risk of being culled compared to those from other countries. Part of this higher risk was linked to a higher culling of low-producing cows. Further analyses and possibilities for the inclusion of LPL in selection criteria for sires to be used in Kenya should be encouraged. 相似文献
6.
Objectives To describe the production and reproduction characteristics of the population under investigation and to compare them with the target population of non-seasonally calving dairy herds, to describe the pattern of culling with respect to length of productive life and length of time after calving, and to identify stages of the production cycle that are associated with increased risk of culling from the dairy herd.
Design A longitudinal population study of eight non-seasonally calving dairy herds in the Camden district of New South Wales.
Results The production and reproduction characteristics of this population were broadly similar to herds participating in the New South Wales Agriculture Dairy Herd Improvement scheme. In agreement with recent surveys, risk of culling increased with increased parity. This was accounted for specifically by increased risk of culling for calving disorders, reproductive tract lesions, and disorders of the udder. Risk of culling for failure to conceive appeared to remain constant throughout productive life. The overall risks for culling were greatest during the first 9 days after calving and 300 days after calving.
Conclusion Reducing the incidence of calving-associated disorders, attention to reproductive management and control of herd mastitis offer opportunities to reduce involuntary culling rates in this population. 相似文献
Design A longitudinal population study of eight non-seasonally calving dairy herds in the Camden district of New South Wales.
Results The production and reproduction characteristics of this population were broadly similar to herds participating in the New South Wales Agriculture Dairy Herd Improvement scheme. In agreement with recent surveys, risk of culling increased with increased parity. This was accounted for specifically by increased risk of culling for calving disorders, reproductive tract lesions, and disorders of the udder. Risk of culling for failure to conceive appeared to remain constant throughout productive life. The overall risks for culling were greatest during the first 9 days after calving and 300 days after calving.
Conclusion Reducing the incidence of calving-associated disorders, attention to reproductive management and control of herd mastitis offer opportunities to reduce involuntary culling rates in this population. 相似文献
7.
Yuzo Kurokawa Miki Okita Hirokazu Kubota Yoshimasa Tsumiyama Ichiro Chikamatsu Akiyoshi Tanaka Taketo Obitsu Kensuke Kawamura 《Animal Science Journal》2021,92(1):e13591
Farm managers' decision to cull dairy cows is based on the cows' milk production, history of disorder(s), and reproductive performance, each of which affects dairy cows' lifetime (herd life and productive lifespan). We investigated the relationships among the incidence of clinical mastitis (CM), the reproductive performance, and the culling rate. We also assessed the effects of these relationships on the lifetimes of dairy cows, using the records made before and after the introduction of an automatic milking system (AMS) at Hiroshima University Farm. Milk yield, CM incidence density, and culling rate of dairy cows increased after the AMS introduction. The CM incidence was associated with an elongation of the calving interval in cows with the same parity. CM in the 1st parity might have caused the reductions of the cows' lifetime and their parity at culling. A higher age at first calving (AFC) was associated with an increase in culling rate but did not lead to a significant decrease in lifetime. Investigations of the factors mediating CM in the 1st parity or AFC with CM incidence or culling rate in the later stages might contribute to the control of lifetime of dairy cows. 相似文献
8.
为了探究荷斯坦牛泌乳前期体况评分（body condition score,BCS）的影响因素及BCS对生产性能和离群寿命的影响,本研究收集江苏省某大型牛场2018年1月至2020年12月共7 811头荷斯坦牛泌乳前期BCS、生产性能测定（dairy herd improvement,DHI）结果及淘汰记录,利用多因素方差分析法在分析奶牛泌乳前期BCS变化及影响因素基础上,重点分析泌乳前期BCS及其变化对泌乳性能和离群寿命的影响,利用Cox回归对泌乳前期不同BCS的荷斯坦牛生存曲线进行绘制,并对不同BCS荷斯坦牛的淘汰原因进行卡方检验。结果表明,全群泌乳前期BCS均值为（2.95 ±0.32）。胎次、产犊季节和泌乳天数对泌乳前期BCS有极显著影响（P<0.01）,1胎牛和夏季产犊的母牛泌乳前期BCS均最高;5~30、31~60、61~100 d BCS呈显著下降。泌乳前期BCS对产奶量、乳脂率、乳蛋白率、体细胞评分等均有极显著影响（P<0.01）。产奶量和高峰奶量随BCS的增加呈极显著下降（P<0.01）。泌乳前期BCS与产奶量、高峰奶量呈极显著负相关（P<0.01）,与乳蛋白率呈极显著正相关（P<0.01）。泌乳前期BCS的变化对SCS和高峰奶量均有显著影响（P<0.05）。泌乳前期BCS对离群胎次和淘汰月龄有极显著影响（P<0.01）。生存分析表明,BCS为2.75的牛只生存概率最大。2胎和4胎母牛、冬季产犊的母牛不同BCS淘汰比例均呈极显著差异（P<0.01）;低产淘汰的牛只泌乳前期BCS淘汰分布具有极显著差异（P<0.01）。在本研究牛群中,当泌乳前期BCS为2.75时,牛只生产性能较佳且淘汰风险最低,本研究为规模化牛场荷斯坦牛泌乳前期的饲养管理提供了参考。 相似文献
9.
试验通过收集出生、产犊和离群的记录,探究宁夏地区荷斯坦牛成母牛的淘汰情况,分析影响该地区奶牛长寿性的因素。对15 523头荷斯坦牛的生产寿命、在群寿命和利用胎次进行描述性统计,分析淘汰时的胎次、季节和泌乳阶段的分布情况;计算生产寿命、在群寿命和利用胎次之间的表型相关,利用固定模型分析场-出生年、出生季节、牧场规模、淘汰原因和头胎产犊月龄对长寿性的影响。结果显示,宁夏地区荷斯坦牛的平均利用胎次为2.36胎,平均生产寿命为736.59 d。荷斯坦牛成母牛在产后第1个月内的淘汰风险最高,随着泌乳阶段的延长,成母牛在每个胎次内的淘汰风险均逐渐降低;随着淘汰胎次的增加,奶牛淘汰更加集中发生在产后泌乳早期;生产寿命、在群寿命和利用胎次之间存在较高的表型相关（均>0.9）,场-出生年、出生季节、牧场规模、淘汰原因和头胎产犊月龄对长寿性有显著影响（P<0.05）,春季出生和22月龄头胎产犊的奶牛长寿性表现更好。本研究初步揭示了宁夏地区荷斯坦牛成母牛的淘汰规律和长寿性的影响因素,为宁夏地区牛群选育成母牛长寿性状奠定了基础。 相似文献
10.
试验通过收集出生、产犊和离群的记录,探究宁夏地区荷斯坦牛成母牛的淘汰情况,分析影响该地区奶牛长寿性的因素。对15523头荷斯坦牛的生产寿命、在群寿命和利用胎次进行描述性统计,分析淘汰时的胎次、季节和泌乳阶段的分布情况;计算生产寿命、在群寿命和利用胎次之间的表型相关,利用固定模型分析场-出生年、出生季节、牧场规模、淘汰原因和头胎产犊月龄对长寿性的影响。结果显示,宁夏地区荷斯坦牛的平均利用胎次为2.36胎,平均生产寿命为736.59 d。荷斯坦牛成母牛在产后第1个月内的淘汰风险最高,随着泌乳阶段的延长,成母牛在每个胎次内的淘汰风险均逐渐降低;随着淘汰胎次的增加,奶牛淘汰更加集中发生在产后泌乳早期;生产寿命、在群寿命和利用胎次之间存在较高的表型相关(均>0.9),场-出生年、出生季节、牧场规模、淘汰原因和头胎产犊月龄对长寿性有显著影响(P<0.05),春季出生和22月龄头胎产犊的奶牛长寿性表现更好。本研究初步揭示了宁夏地区荷斯坦牛成母牛的淘汰规律和长寿性的影响因素,为宁夏地区牛群选育成母牛长寿性状奠定了基础。 相似文献
11.
The epidemiology and genetic variability of the most common dairy cow diseases were examined. This paper describes the data set, lactation incidence rates and culling during lactation. The data set consisted of the lactation records of 73,368 Finnish Ayrshire dairy cows. Each cow was under observation for 2 days before and 305 days after calving. Lactational incidence rates (%) for the most common diseases were: ovulatory dysfunction 7.0, ketosis 6.0, acute mastitis 5.4, an oestrus and suboestrus 5.2, retained placenta 4.5, parturient paresis 3.8 and teat injury 2.6. Multiple logistic regression was utilized to investigate the possible effects of certain factors on culling. The model predicted the log odds for culling as an additive function of the explanatory factors. Using the estimated odds and forming the odds ratios it was possible to investigate, relative risks between any combination of groups of the explanatory factors. The risk of culling increased with parity after the second parturition, and with increasing herd milk yield. Mastitis and parturient paresis had positive associations with culling, while ketosis and infertility had negative associations. Heritability estimates for culling in various parity groups were from 2 % to 9 % on the binomial scale corresponding from 5 % to 14 % on the normal scale. There was a neagtive genetic correlation between culling and previous milk production. 相似文献
12.
《Livestock Production Science》1993,33(1-2):77-90
A range of preplanned dry period lengths in a dairy herd was evaluated, at different culling strategies and feeding regimes, by means of a dynamic stochastic model simulating the production at herd level. Dry period lengths were studied in the range of 4 to 10 weeks. The culling strategies exhibited two different rates of voluntary culling for reproductive failure and milk production, and the feeding regimes consisted of grass silage ad lib. and either 8 or 12 kg of concentrates/day in the first 24 weeks of lactation. The economic result was studied under a herd size and a milk quota constraint, respectively. A dry period of seven weeks appeared to be preferable under most circumstances. The net revenue per unit of milk sold was less sensitive to dry period length than the net revenue per cow per year. No major interactions between dry period length and culling strategy or feeding regime were found. The conclusions were fairly insensitive to price changes, and to variation in the assumed effect on lactational performance of dry period lengths from 6 to 8 weeks. 相似文献
13.
To assess the profitability of control schemes for Mycobacterium avium subspecies paratuberculosis (Map)-infection implemented in dairy herds, accurate estimates of its production effects are needed. This study aimed at quantifying the variation in milk yield of dairy cows according to their Map-infection status. The cow-status was determined by combining (i) its testing(s)-result(s) (serum ELISA, faecal culture (FC), PCR, Ziehl staining), (ii) the Map-status of its herd, and (iii) its possible vaccination against Map. A total of 15 490 cows in 569 herds located in western France was considered. The effect on test-day milk yield (TDMY) of the cow-status to Map was assessed separately in parity 1, 2 and 3 or more, using mixed linear models, after adjustment for herd-season (random), days in milk and breed. Average TDMY was significantly lower in cows from herds with at least one Map-infected cow (defined as positive herds). Individual TDMY showed a reduction ranging from 1.58 to 3.30, 2.03 to 2.51, 5.36 to 7.20 kg/day (P < 0.001) depending on parity for unvaccinated cows and testing ELISA-positive, PCR- or FC-positive, and Ziehl-positive, respectively, compared to cows in Map-free herds. The loss in milk yield increased with increased parity in ELISA-positive and Ziehl-positive cows. Cows that were both tested ELISA-positive and vaccinated had a smaller loss in TDMY than those that were unvaccinated. The estimates from this study can be used to further assess the economic impact associated with Map-infection in dairy herds or to help in the culling decisions regarding infected cows. 相似文献
14.
Voluntary culling on low milk yield and the economic returns for herds with a stable number of milk cows was investigated for spring calving dairy herds in the Republic of Ireland. The analysis was conducted at annual involuntary removal rates: 15, 20 and 25% and replacement costs as percent of beef value 94, 126, 157%. Varying cow replacement rate above involuntary removal rate by voluntary culling increased milk sold per cow in year 16 to a maximum of +5 to +10% after practicing a fixed strategy for 16 years. Greatest absolute and relative gains in yield occur from voluntary culling at the lowest involuntary replacement rate. Voluntary culling up to 3 to 8 percentage units above involuntary cow replacement rate maximizes economic returns per cow in herd when the market price for replacement heifers exceeds 150% of their beef value. Maximum voluntary culling may be practiced for prices near or below beef value. 相似文献
15.
Johne's disease (JD) is caused by infection with the organism Mycobacterium avium spp. paratuberculosis, leading to chronic diarrhoea and ill thrift in adult cattle. JD is considered to adversely affect farm performance and profitability. This retrospective case study was undertaken on a single commercial dairy herd in the south west of Ireland. Animal production records were interrogated to assess the effect of JD on milk yield (total kg per lactation), somatic cell count (the geometric mean over the lactation), reasons for culling, cull price and changes in herd parity structure over time. JD groups were defined using clinical signs and test results. One control animal was matched to each case animal on parity number and year. Specific lactations (clinical, pre-clinical and test-positive only) from 1994 to 2004 were compared between JD case and control cows. A significantly lower milk yield (1259.3 kg/lactation) was noted from cows with clinical JD in comparison to their matched control group. Clinical animals had an average cull price of €516 less than animals culled without signs of clinical disease. In contrast, little effect was noted for sub-clinical infections. These direct effects of JD infections, in combination with increased culling for infertility and increasing replacement rates, had a negative impact on farm production. Results from this study provide preliminary information regarding the effects of JD status on both herd and animal-level performance in Ireland. 相似文献
16.
Improved knowledge about conception rates influences the decision to stop insemination in dairy cows
The conception rate in dairy cows is dependent on a number of cow factors such as days in milk and insemination number. Unfortunately, some of these factors were not accounted for in optimal insemination and replacement decision models. By using wrong estimates of the conception rate, the calculated optimal insemination and replacement policy might differ from the real optimal insemination and replacement policy. The objective of this study was to evaluate different sets of conception rates with an increasing level of accuracy to determine the insemination policy. An existing dynamic program for optimal insemination and replacement was used to compare three different scenarios in the estimation of conception rates, based on the reproductive performance of Dutch dairy cattle: (i) constant conception rate throughout lactation, (ii) conception rate dependent on parity and months in milk, and (iii) conception rate dependent on parity, months in milk and insemination number. The time step of the model was 30.4 days (1 month). The discounted future cash flow of culling a cow at each time step (replace a heifer immediately) was compared with keeping that cow under optimal future decisions. The difference between immediate culling and optimal decisions is defined as the retention pay-off. The insemination value was calculated as the difference between the future cash flow between immediate insemination of a cow and waiting one time-step. The results show that the difference in the insemination values and the optimal time to stop insemination depend on parity, lactation stage and the relative milk yield. In older cows with equal milk yields and at the same months in milk, the insemination value was lower than in younger cows. Within a parity, the insemination value was higher for cows with a higher milk yield. On individual cow level, using more accurate conception rate as input in the optimal insemination and replacement model might reduce miscalculation of the economic consequences for at least of €20-€38 per cow per year. Basing insemination decisions on less accurate input of the probabilities of conception, however, did not have an economic consequence at the herd level. In conclusion, using the appropriate conception rate as input in the optimal insemination and replacement model would increase the precise decision for the optimal time to stop insemination and hence improve the reproductive management efficacy. 相似文献
17.
Efforts to reduce the prevalence of Staphylococcus aureus intramammary infection were monitored in 3 Ohio dairy herds. Bacteriologic culturing of milk from all lactating cows in each herd was completed multiple times to identify infected cows and monitor reduction. Partial budgeting techniques were used to determine the economic outcome of the reduction program. Of particular emphasis was the economic impact of culling to maintain or achieve milk quality premium payments on the basis of bulk tank somatic cell counts. The prevalence of S aureusinfected cows was reduced in each herd. Culturing of milk from all lactating cows appeared to be an effective method to identify infected cows. Although numbers were limited, it also appeared that culturing of composite quarter samples was effective as a herd screening test to identify S aureus-infected cows. Bacteriologic culturing had a negative financial impact in all 3 herds. Using partial budgeting to assess the economic impact of the programs, it was determined that 2 herds experienced negative financial impacts as a result of an excess culling rate when compared with a 12-month baseline period prior to the initiation of the project. All herds had increased milk production per cow during the study as measured by the mature-equivalent method. However, when actual production was considered, increased milk production in each herd was not as great as that of other Ohio herds enrolled on Dairy Herd Improvement Association testing programs.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
18.
Gröhn YT González RN Wilson DJ Hertl JA Bennett G Schulte H Schukken YH 《Preventive veterinary medicine》2005,71(1-2):105-125
The objective of this study was to estimate the effects of clinical mastitis (CM) (both with and without specific pathogen identification) occurring in different stages of lactation on length of herd life in two New York State dairy farms. The 2,697 cows in the study were followed for one lactation (the first-occurring one on or after 1 October 1999), until it ended because of a new lactation, culling, or end of study (31 March 2001 in one farm; 31 July 2001 in the other). A Cox proportional hazards model with time-dependent covariates, in SAS((R)), was used to measure, within a lactation, the effect of the first occurrence of CM (without specific pathogen identification) occurring 1--7, 8--66, 67--100, 101--225, or >or=226 days in milk (DIM), on how long cows remained in the herd. For the first occurrence of CM due to Streptococcus spp., Staphylococcus aureus, Staphylococcus spp., Escherichia coli, Klebsiella spp., and 'no pathogen isolated', the intervals were before and after the median DIM of first occurrence of each pathogen. There were too few cases due to Arcanobacterium pyogenes, and 'other pathogens grouped together' to split into intervals, so they were modeled as binary variables, i.e. as they occurred. CM was modeled using time-dependent covariates, to account for its differing effects throughout lactation on culling. Other variables controlled for were herd, parity, calving season, and other significant diseases. In the dataset, the lactational incidence risk of the first occurrence of CM was 18.2%; 20.0% of the cows did not survive the lactation that was studied. The overall annual culling percentage for both herds during the study period (including all cows, whether eligible for the study or not) was 35.6%. For cows with CM without pathogen identification, their highest hazard ratio (HR) of culling occurred from 67 to 100 DIM. All of the pathogens modeled markedly reduced herd life. On average over the entire lactation, cows with Staphylococcus spp. CM had the highest HRs for culling, although there were no significant differences among pathogens (at p=0.0018 (reflecting 28 pairwise comparisons)). For early-occurring (before median DIM of first occurrence) S. aureus CM, the daily rate of change of the HR of culling increased over time. The HRs for culling were particularly high for late-occurring (after median DIM of first occurrence) E. coli and Klebsiella spp. CM early in the interval, but the daily rate of change of the hazard of culling for these two pathogens decreased sharply over time. Treating CM as time-dependent therefore allowed us to measure in greater detail, its varying effects (of when it occurred) on herd life. 相似文献
19.
Abdelgadir Musaad Bernard Faye Abdelmoneim Abu Nikhela 《Tropical animal health and production》2013,45(4):1039-1046
Weekly milk records of 47 she-camels in a multibreed dairy camel herd were collected for over a period of 5 years. A total of 72 lactation curves were defined, and relationships with parity, calving season, lactation length, milk production level, following lactations, and dam weight were analyzed. Overall mean values were milk yield up to 12 months, 1,970?±?790 l; lactation length, 12.5 months; persistency, 94.7 %; weekly peak yield, 50.7 l; monthly peak yield, 220?±?90 l; and the number of weeks to reach peak yield, 28. The highest productivity was recorded in summer with a weekly mean of 48.2?±?19.4 l, compared with 34.1?±?16.3 l in winter. The highest average yield recorded was for camels at sixth parity, whereas the highest weekly peak was at eighth parity, and highest persistency at fifth parity. Camels that calved during the cold months (November to February) were most productives, with the highest persistency, peak yield, and longest lactation length. Four types of curves were identified corresponding to different parities and milk yield levels. Based on these data, specific models for camels are proposed. 相似文献
20.
Onteru SK Fan B Nikkilä MT Garrick DJ Stalder KJ Rothschild MF 《Journal of animal science》2011,89(4):988-995
Profits for commercial pork producers vary in part because of sow productivity or sow productive life (SPL) and replacement costs. During the last decade, culling rates of sows have increased to more than 50% in the United States. Both SPL and culling rates are influenced by genetic and nongenetic factors. A whole-genome association study was conducted for pig lifetime reproductive traits, including lifetime total number born (LTNB), lifetime number born alive (LNBA), removal parity, and the ratio between lifetime nonproductive days and herd life. The proportion of phenotypic variance explained by markers was 0.15 for LTNB and LNBA, 0.12 for removal parity, and 0.06 for the ratio between lifetime nonproductive days and herd life. Several informative QTL regions (e.g., 14 QTL regions for LTNB) and genes within the regions (e.g., SLC22A18 on SSC2 for LTNB) were associated with lifetime reproductive traits in this study. Genes associated with LTNB and LNBA were similar, reflecting the high genetic correlation (0.99 ± 0.003) between these traits. Functional annotation revealed that many genes at the associated regions are expressed in reproductive tissues. For instance, the SLC22A18 gene on SSC2 associated with LTNB has been shown to be expressed in the placenta of mice. Many of the QTL regions showing associations coincided with previously identified QTL for fat deposition. This reinforces the role of fat regulation for lifetime reproductive traits. Overall, this whole-genome association study provides a list of genomic locations and markers associated with pig lifetime reproductive traits that could be considered for SPL in future studies. 相似文献