• Asian-Australasian Journal of Animal Sciences
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• 제13권10호
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• pp.1347-1352
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• 2000

The objectives of the study were to examine non-genetic factors that influence somatic cell counts in dairy cattle and to estimate the genetic parameters of somatic cell counts. A total of 34, 097-test day somatic cell count records were obtained from the Zimbabwe Dairy Services Association (ZDSA). The data were from 5, 615 Holstein daughters of 390 sires and 2, 541 dams tested between May 1994 and December 1998. First lactation cows contributed 22, 147 records to the data set, while 11, 950 records were from second and later parity cows. The model for analysis included fixed effects of month of calving, year of calving, stage of lactation, calving interval and test date. Milk yield and age on test day were fitted in the model as covariates. The additive genetic effects pertaining to cows, sires and dams and the residual error were the random effects. The Average Information Restricted Maximum Likelihood algorithm was used for analysis. The heritability of somatic cell scores was low at $0.027{\pm}0.013$ for parity one cows and $0.087{\pm}0.031$ for parity two and above. Repeatability estimates were $0.22{\pm}0.01$ and $0.30{\pm}0.01$ for the two lactation groups, respectively. Genetic and phenotypic correlations between the somatic cell scores and test day milk production were small and negative. It seems that there is no genetic link between somatic cell counts and milk yield in Holstein cattle in Zimbabwe. The results also seem to indicate that somatic cell count is a trait that is mainly governed by environmental factors.

• Asian-Australasian Journal of Animal Sciences
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• 제16권6호
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• pp.789-793
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• 2003

An investigation was conducted on 729 Hariana cows maintained at Government Livestock Farm, Hisar, from 1973 to 1999, with an objective to compare the efficiency of various selection indices for attaining desired genetic gains in the index traits. The various traits included were age at first calving (AFC), service period (SP), calving interval (CI), days to first service (DFS), number of services per conception (NSPC), lactation milk yield (LY), peak yield (PY), dry period (DP). Except for LY, PY and AFC the heritabilities of all other traits were low. Desirable associations among reproductive traits are supportive of the fact that any one of these traits incorporated in simultaneous selection is expected to cause correlated response in other traits. Production traits (LY and PY) were positively correlated, while DP had low negative genetic correlation with LY, and high genetic correlation with PY. Thus, DP can be taken as additional criteria in selection index for better over all improvement. Almost all production traits except DP had low negative correlation with AFC, SP, DFS and CI meaning that reduction in reproduction traits up to certain level may increase production performance. While, the correlation of NSPC with LY and PY was moderate positive. Among four trait indices I23: incorporating PY, AFC, SP and NSPC and among three trait indices I1: incorporating LY, AFC and SP were the best as these required least number of generations (4.87 and 1.35, respectively) to attain desired goals. Next in order of preference were PY or LY along with DP and SP as the best indices (I20 and I16) of which, index with PY may be preferred instead of LY as it produced considerably high correlated response in LY and reduction in NSPC as well.

• Asian-Australasian Journal of Animal Sciences
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• 제12권3호
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• pp.336-340
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• 1999

Age at maturity was studied in 661 Nili Ravi buffaloes maintained at six dairy farms in Pakistan. The mean age at maturity in the overall data from the six farms was $976.49{\pm}9.2$ days. Significantly lower mean age at maturity $(957.93{\pm}10.68\;days)$ was observed at Military Dairy Farm, Khyber Okara, Military Daiiy Farm, Punjnad and Livestock Research Station, National Agricultural Research Centre, Islamabad (Group I) compared to $(1015.26{\pm}17.39\;days)$ other three Military Dairy Farms, Peshawar, Nowshera and Rawalpindi (Group II). The advantages associated to early age at maturity were as following. Male and female calves were heavier $(38.35{\pm}0.17\;and\;31.84{\pm}15kg,\;respectively)$ in Group I as compared to $(29.27{\pm}0.26\;and\;26.27{\pm}0.26kg)$ in Group II. Milk yield per lactation was significantly higher in Group I $(1912{\pm}12\;lit.)$ as compared to $(1833.36{\pm}16.56\;lit.)$ in Group II. Lactation length was significantly longer $(284.41{\pm}1.23\;days)$ in Group I as compared to $(277.77{\pm}2.02\;days)$ in Group II. Dry period and service period were significantly shorter $(241.59{\pm}4.18\;and\;217.05{\pm}4.95\;days,\;respectively)$ in Group I as compared to $(306.39{\pm}78\;and\;280.95{\pm}9.32\;days)$ in Group II. The mean age at first calving and sex ratio were low ($1282.75{\pm}10.14$ days and 100 ♀ ♀:130.7 ♂ ♂) in Group I as compared to ($1308.7{\pm}16.44$ days and 100 ♀ ♀:152.15 ♂ ♂) in Group II but the differences were non significant.

• 한국유기농업학회지
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• 제27권3호
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• pp.365-380
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• 2019

본 연구는 봄에 출생한 송아지 10두(3.90±0.26개월령)와 가을에 출생한 송아지 10두(4.10±0.30개월령)를 약 24개월간 조사료와 농후사료를 분리 급여하거나 또는 TMR을 급여하여 분만 후의 유생산과 비유지속성을 조사하였다. 처리구는 사료 급여 형태와 분만계절의 2가지 요인으로 육성기에 조사료와 농후사료를 분리하여 급여하고 봄에 분만한 CS구, 육성기에 조농분리 급여한 후 가을 분만한 CF구, 육성기에 TMR을 급여한 후 봄에 분만한 TS구 그리고 육성기에 TMR을 급여하고 가을에 분만한 TF구의 4가지로 구분하였다. 육성기의 건물섭취량은 분만계절의 영향을 받아 가을에 분만한 구가 봄에 분만한 구보다 높게 나타났으나(P<0.01), 사료급여 방법에 의해서는 유의한 차이를 나타내지 않았다. CP 섭취량과 TDN 섭취량은 분만계절(P<0.05)과 사료급여(P<0.01)에 의해 유의한 영향을 받았으며 가을에 분만한 구가 봄에 분만한 구에 비해 약 1.2% 높게 나타났고 TMR 급여구가 조농분리 급여구보다 약 4.7%정도 높은 결과를 보였다. 평균 산유량과 9, 10개월차의 산유량은 사료급여 방법에 의해 유의한 영향을 받아 TMR 급여구(TS구, TF구)가 조농분리 급여구(CS구, CF구) 보다 높은 결과를 나타내었다(평균 P<0.05; 9개월차와 10개월차 P<0.01). 평균 비유지속성은 분만계절(P<0.05)과 사료급여 방법(P<0.01)에 의해 유의한 영향을 받아 가을에 분만한 구가 봄에 분만한 구에 비해 높은 결과를 보였으며 TMR 급여구가 조농분리 급여구 보다 높은 결과를 나타냈다. 산유량의 결과와 유사하게 비유후기인 9, 10개월차에 사료급여에 의해 통계적 유의차를 보여(P<0.01) TMR 급여구가 약 8% 높았으며, 7개월차(P=0.12)와 8개월차(P=0.09)에도 높은 경향을 나타내었다. 따라서 육성기에 TMR을 급여하고 가을에 분만할 경우 초산우의 산유량과 비유지속성 증진에 효과적일 것으로 사료된다. 평균 유지율은 사료급여의 영향을 받아 TMR 급여구가 조농분리 급여구 보다 7.8% 높았는데(P<0.01) 육성기 TMR 급여가 분만 후 섭취행동에 영향을 주어 반추위의 안정화로 인해 유지율이 증가한 것으로 사료된다. 분만 후 3개월차에는 봄에 분만한 구가 가을에 분만한 구보다 유지방 함량이 낮았으며(P<0.05) 이는 계절적 차이에 의한 것으로 사료된다. MUN은 평균과 4, 5 및 6개월차에 조농분리 급여구에서 유의하게 높았다(4개월차 P<0.01; 5, 6개월차 P<0.05). 체세포수는 평균과 분만 후 3, 4개월차에 TMR 급여구가 조농분리 급여구 보다 높은 결과를 보였다(P<0.01). 결과를 종합해보면, 육성기에 TMR 급여방법을 적용하고 가을에 분만하는 경우 봄에 분만하는 경우에 비해 여름철 고온의 영향을 비교적 덜 받아 산유량과 비유지속성 뿐만 아니라 유지율 등이 개선되어 경제성이 향상되는 효과를 보았다. 그러나 본 실험은 봄과 가을의 분만계절이 미치는 영향만을 보았기 때문에 여름과 겨울의 분만계절의 영향에 대한 추가 실험이 필요할 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권7호
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• pp.943-950
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• 2015

Heat stress has adverse effects on fertility of dairy animals. Decline in fertility is linearly associated with an increase in combination of both temperature and humidity. The purpose of this study was to investigate the relationship between temperature humidity index (THI) and the pregnancy rate of Murrah buffaloes in a subtropical climate. The effects of genetic and non-genetic factors viz., sire, parity, period of calving and age group at first calving were found non-significant on pregnancy rate. The effect of THI was found significant (p<0.001) on pregnancy rate of Murrah buffaloes calved for first time and overall pregnancy rate. The threshold THI affecting the pregnancy rate was identified as THI 75. The months from October to March showed THI<75 and considered as non heat stress zone (NHSZ), while months from April to September were determined as heat stress zone (HSZ) with $THI{\geq}75$. The lowest overall pregnancy rate (0.25) was obtained in July with THI 80.9, while the highest overall pregnancy rate (0.59) was found in November with THI 66.1. May and June were identified as critical heat stress zone (CHSZ) within the HSZ with maximum decline (-7%) in pregnancy rate with per unit increase in THI. The highest overall pregnancy rate was estimated as 0.45 in NHSZ with THI value 56.7 to 73.2. The pregnancy rate was found to have declined to 0.28 in HSZ with THI 73.5 to 83.7. However, the lowest pregnancy rate was estimated as 0.27 in CHSZ with THI value 80.3 to 81.6.

• Asian-Australasian Journal of Animal Sciences
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• 제22권5호
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• pp.611-617
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• 2009

This study was aimed at a genetic evaluation of Iranian Holstein cattle for milk and fat yields and calculating daughter yield deviation (DYD) of bulls. The data file that was used in this research included 367,943 first three lactation records of 186,064 Holstein cows which calved between 1983 and 2006 in 11,806 herd-year-season groups. The model included herd-year-season of calving and age at calving as fixed effects and animal and permanent environment as random effects. Mean breeding values of cows for each year were regressed on birth year to estimate genetic trends. Genetic trends in milk and fat yields were greater for cows born after 1997 (59.38 kg/yr and 1.11 kg/yr for milk yield and fat yield, respectively). Animal evaluations were partitioned into contribution from parent average, yield deviation (YD) and progeny. DYD of bulls was calculated as described by VanRaden and Wiggans (1991). DYD provides an indication of the performance of the daughters of a bull without consideration of his parents or sons. Variance of bull DYD was greater than variance of their predicted transmitting ability (PTA). Correlation of bull DYD and PTA was dependent on the number of daughters and when this increased, the correlation of DYD and PTA was increased. Also as lactation number of daughters increased, the correlation of bull DYD and PTA was increased.

• Asian-Australasian Journal of Animal Sciences
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• 제33권2호
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• pp.197-202
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• 2020

Objective: The objective of this study was to identify environmental factors strongly associated with and to estimate genetic parameters of reproductive traits in Japanese Black heifers. Methods: Data included reproduction records of Japanese Black heifers born between 2004 and 2014. First service non-return rate (NRR) to 56 days from first to successful insemination (FS), number of services per conception (IN), age at first calving (AFC) and gestation length were analyzed with the use of the general linear model. Genetic parameters were estimated with the use of the univariate animal model of the residual maximum likelihood. Results: Averages of reproductive traits over eleven years were assessed, and the effects of farm, year, month, artificial insemination technician and interaction of farm×year on the traits were determined. Estimated heritability of FS was very low and that of AFC was higher than that of the other traits. A close genetic relation was observed among NRR, IN, and FS; however, their heritabilities were very low. AFC shows favorable genetic correlation with IN and FS. Conclusion: Low heritabilities of most reproductive traits in Japanese Black heifers are strongly influenced by farm management practices, and that large residual variances make genetic evaluation difficult. Among the reproductive traits, AFC is potentially more useful for genetic improvement of heifer reproductive traits because it has high heritability and favorable genetic correlations with IN and FS.

• 한국수정란이식학회지
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• 제28권4호
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• pp.319-324
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• 2013

This study was conducted among 120 different breed cows at selected areas of Sirajgonj district from March to July 2010 to compare the reproductive performance of crossbred and Desi cows at farmer's level. The results showed that the average daily milk yield of Desi, Shahiwal ${\times}$ Desi, Friesian ${\times}$ Desi and Jersey ${\times}$ Desi cows was $2.3{\pm}0.2$, $4.9{\pm}0.9$, $6.0{\pm}1.0$ and $5.7{\pm}0.9$ liters, respectively. The milk yield of crossbred cows ($5.5{\pm}0.6$ liters/day) was significantly (p<0.01) higher than Desi cows ($2.3{\pm}0.2$ liters/day). The average age at puberty of Shahiwal ${\times}$ Desi, Friesian ${\times}$ Desi and Jersey ${\times}$ Desi was significantly (p<0.01) lower than that of Desi breed. The crossbred cows had significantly (p<0.01) lower pubertal age ($20.4{\pm}1.2$) than Desi ($25.9{\pm}1.1$). The age at first calving in Desi cows was significantly (p<0.01) higher ($37.6{\pm}1.1$ months) than crossbred cows ($31.2{\pm}1.3$ months). The average gestation length of Desi, Shahiwal ${\times}$ Desi, Friesian ${\times}$ Desi and Jersey ${\times}$ Desi was $289.9{\pm}1.4$, $285.0{\pm}0.0$, $285.0{\pm}4.2$ and $282.1{\pm}2.4$ days, respectively. It is suggested that the overall reproductive performance of Friesian ${\times}$ Desi, Jersey ${\times}$ Desi and Shahiwal ${\times}$ Desi cows were better than that of Desi cow.

• Asian-Australasian Journal of Animal Sciences
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• 제19권5호
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• pp.627-631
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• 2006

The objective of this study was to evaluate the association of genetic differences in the bovine leptin gene and milk yield, reproduction, body condition score (BCS), and plasma glucose level in Iranian Holstein cows. In total, two hundred and thirty eight cows were used and genotyped for a restricted fragment length polymorphism at the leptin gene locus. Two genotypes, AA and AB, have been distinguished which have the frequencies of 0.89 and 0.11, respectively. The genotypes were distributed according to the Hardy - Weinberg equilibrium ($x^2$ = 0.733). During the first 12 wk of lactation, milk yield and composition, live weight, BCS and plasma glucose were measured in 50 cows. Data were analyzed based on a repeated measures ANOVA. During this period, milk yield and composition, live weight, BCS and plasma glucose level were similar among the genotypes. The first cumulative 60-d milk yield, 305-d milk yield, days to first breeding, days open and days from first breeding to conception using previous lactation records were also analyzed using Standard Least Square within mixed models. Fixed effects were year, season, parity and age at calving, and sire. For the reproductive traits the cumulative first 60-d milk yield was also added to the model. Animal was fitted as a random effect. A significant association was detected between the RFLP-AB genotype and 305-d milk yield (p<0.05). The first 60-d cumulative milk yield was similar for the two genotypes (p = 0.21) and tended to be higher in the heterozygous cows. The heterozygous genotypes at the above mentioned locus had a trend to better reproductive performance than the homozygous. The results demonstrate that the RFLP B-allele can yield a higher 305-d milk production with a trend to better reproductive performance.

• 한국수정란이식학회지
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• 제1권1호
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• pp.35-49
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• 1986

Recipients are an integral part of embryo transfer and they are expensive to maintain as a good recipient. Recipient management is one of the most important components in a successful embryo transfer program. Management includes selection and subsequent care of the animals. A good recipient is basically on "open" cows or heffers whose reproductive tract is capable of receiving one or two embryos and incubating it to term. Potential recipients should be always be healthy and cycling normally ranging from 18 to 23 days. A thorough veterinary examination is recommended for candidate of recipients and cattle for questionable health should be eliminated from the recipient herd. Age and size of recipients are particularly important considerations when heifers are used, because of most embryos available for transfer are from large dams and sires. Body condition can influence a recipient's production, reproduction and health. Obese and underconditioned cattle should be avoided for use. Transfer of fresh embryos especially requires precise synchronization of donors and recipients. For estrus synchronization, PGF$_2$$\alpha$ is injected twice 10 to 12 days apart and short4erm progestagen treatment is applied to potential recipient cattle by coil into vagina (PRID) or ear implant (Synchro-Mate-B). The highest pregnancy results are achieved in recipients at exact synchrony with donors or 12 to 24 hr earlier than donors. Estrus detection is a major factor in breeding efficiency. High accuracy can be achieved by use of heat mount detection alds or by obserbing cattle for 30-minute peroids 3 times daily. Assay progesterone in milk can be used to discrIminate between pregnant and nonprenant recipients. Rectal palpation on day 35 to 70 after is an accurate and safe method of pregnancy diagnosis. Embryonic mortality in recipients may be associated with factors such as high environmental temperature and nutritional or lactational stress in early lactation period. Achievement of short calving interval requires concentrated management activity during the first 90 days following calving. Acceptable candidate for a recipient should be routinely vaccinated for infectious diseases. Proper nutritional programs according to NRC requirements and body condition scoring system for recipient cattles are vital to the ultimate success of an embryo transfer program.r program.