Article

Genetics of milk yield and fertility traits in Holstein-Friesian cattle on large-scale Kenyan farms

Imperial College at Wye, Ashford, Kent, UK.
Journal of Animal Science (Impact Factor: 1.92). 08/2001; 79(7):1742-50.
Source: PubMed

ABSTRACT Purebred Holstein-Friesian cows are the main exotic breed used for milk production on large, medium, and small farms in Kenya. A study was undertaken on seven large-scale farms to investigate the genetic trends for milk production and fertility traits between 1986 and 1997 and the genetic relationships between the traits. This involved 3,185 records from 1,614 cows, the daughters of 253 sires. There was a positive trend in breeding value for 305-d milk yield of 12.9 kg/ yr and a drop in calving interval of 0.9 d/yr over the 11-yr period. Bulls from the United States (U.S.) had an average total milk yield breeding value 230 kg higher than the mean of all bulls used; Canada (+121 kg), Holland (+15 kg), the United Kingdom (U.K., 0 kg), and Kenya (-71 kg) were the other major suppliers of bulls. Average breeding values of bulls for calving interval by country of origin were -1.31 (Canada), -1.27 (Holland), -0.83 (U.S.), -0.63 (Kenya), and 0.68 d (U.K.). The genetic parameters for 305-d milk yield were 0.29 (heritability), 0.05 (permanent environment effect as proportion of phenotypic variance) resulting in an estimated repeatability of 0.34. Using complete lactation data rather than 305-d milk yield resulted in similar estimates of the genetic parameters. However, when lactation length was used as a covariate heritability was reduced to 0.25 and the permanent environment effect proportion increased to 0.09. There was little genetic control of either lactation length (heritability, 0.09) or calving interval (heritability, 0.05); however, there were strong genetic correlations between first lactation milk yield, calving interval, and age at first calving.

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    • "In view of these facts, several researchers estimated the heritability of total milk yield in Holstein cows. Estimation ranged from 0.06 to 0.39 (Klopcic et al., 1997; Ojango and Pollott 2001; Hermiz et al., 2005; Cilek and Sahin 2009; Ayied et al., 2011; Usman et al., 2012; Nawaz et al., 2013; Hamrouni et al., 2014), while heritability of LL ranged from 0.02 to 0.49 (Hermiz et al., 2005; Ayied et al., 2011; Usman et al., 2012; Nawaz et al., 2013). http://www.openveterinaryjournal.com F.R. Al-Samarai et al. "
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    ABSTRACT: A total of 956 lactation records of Holstein cows kept at Kaa Albon station, Imuran Governorate, Yemen during the period from 1991 to 2003 were used to investigate the effect of some genetic and non-genetic factors (Sire, parity, season of calving, year of calving and age at first calving as covariate) on the Total Milk Yield (TMY), Lactation Length (LL), and Dry Period (DP). Components of variance for the random effects (mixed model) were estimated by Restricted Maximum Likelihood (REML) methodology. Sires were evaluated for the TMY by three methods, Best Linear Unbiased Prediction (BLUP) using Harvey program, Transmitting Ability (TA) according to the Least Square Means of sire progeny (TALSM) and according to Means (TAM). Results showed that TMY and DP were affected significantly (P < 0.01) by all factors except season of calving and age at first calving, while LL was affected significantly (P< 0.01) only by year of calving and parity. The averages of the TMY, LL, and DP were 3919.66 kg, 298.28 days, and 114.13 days respectively. The corresponding estimates of heritability (h²) were 0.35, 0.06, and 0.14 respectively. The highest and lowest BLUP values of sires for the TMY were – 542.44 kg and 402.14 kg, while the corresponding estimates for TALSM and TAM were – 470.38, 380.88 kg and – 370.12, 388.50 kg respectively. The Spearman rank correlation coefficients among BLUP, TALSM and TAM ranged from 0.81 to 0.67. These results provide evidence that the selection of sires will improve the TMY in this herd because of the wide differences in genetic poetical among sires, and a moderate estimation of heritability.
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    • "This implies that the reported infertility and increase in mammary and metabolic disorders in Kenyan herds may be as a result of the previous selection practices. The availability of records on milk production and reproduction traits in the Kenyan dairy cattle population has enabled investigations into the forms and types of relationships between these traits (Ojango & Pollott, 2001; Ilatsia et al., 2007). However, records are not available on udder health and metabolic disorders in lactating animals, such as somatic cell count, mastitis, milk fever, displaced abomasums and ketosis. "
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    ABSTRACT: In Kenya, selection of dams for the national contract mating scheme is based on 305-day lactation milk yield (TMY) performance across parities. At farm level, only cows that had good TMY performance in previous parity are retained for the subsequent lactation. This strategy has resulted in improved milk production performance, although increased incidences of physiological disorders, mastitis and reduced fertility have been reported in high-yielding cows. Records on functional traits relative to milk yield are scant. Properties of lactation curves could be used indirectly to explain the productive and functional efficiency of dairy cows. This study assesses the relationship between lactation traits, based on the lactation curve, to evaluate the effects of selection for TMY on lactation curve properties and to assess the effects of selection decisions based on first lactation on performance in later lactations. A repeatability analysis revealed negative genetic correlations between peak milk yield (MYmax) and persistency (S); MYmax and days in milk at peak (DIMP); and TMY and DIMP. Genetic correlations were positive between DIMP and S, and TMY and MYmax. This implies that selection for high TMY would result in high MYmax and a reduction in DIMP. This alters the shape of the lactation curve, shifting production pressure to early lactation, which aggravates a negative energy balance, thus compromising the physiological integrity of the cow. Continuous selection for high TMY could be responsible for the reported decline in reproductive efficiency and lactation physiology. Correlation estimates between traits in different parities were bidirectional (correlation estimates changed signs (+/-) in different parities), implying that selection decisions made in lactation 1 may not have similar outcomes in lactations 2 and 3. Selection at farm level should be optimised by using records from three parities, as is done in the contract mating scheme.
    South African Journal Of Animal Science 08/2014; 44(3):245. DOI:10.4314/sajas.v44i3.6 · 0.35 Impact Factor
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    • "Failure to implement scientifically developed and balanced breeding objectives in South African Holstein cattle is cause for concern. The widely reported unfavourable genetic relationships between milk yield and fertility (Van Arendonk et al., 1989; Frick & Lindhe, 1991; Bagnato & Oltenacu, 1994; Campos et al., 1994; Hoekstra et al., 1994; De Jong, 1997; Ojango & Pollot, 2001; Kadarmideen, 2004; Pryce et al., 2004) and milk yield and mastitis (Emanuelson et al., 1988; Simianer et al., 1991; Uribe et al., 1995; Mrode & Swanson, 1996) raise concern that udder health and reproductive performance could deteriorate as a correlated response to selection for increased yield. Recent research (Makgahlela et al., 2008; Dube et al., 2009) supports these concerns. "
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    ABSTRACT: Well-defined breeding objectives form the basis of sound genetic improvement programmes. Breeding objectives for Holstein cattle in South Africa were developed in the current study. Economic values were calculated for those economically relevant traits that had adequate bio-economic data, namely milk volume, fat yield, protein yield, liveweight, longevity, calving interval and somatic cell score (SCS). A bio-economic herd model for pasture-based and concentrate-fed systems in South Africa was used to calculate economic values by determining changes in profit arising from an independent unit increase in each trait. Alternative payment systems were used from four major milk buyers in South Africa. Relative economic values, standardized to the value of protein yield, were used to compare the relative importance of traits. Protein yield and longevity consistently had positive economic values and the converse was true for liveweight and calving interval. Economic value for volume was positive or negative, depending on whether the payment system rewarded or ignored volume. Sensitivity analysis showed that economic values were reasonably robust against fluctuations in the cost of feed and price of beef; with the exception of fat yield, whose value became negative when feed price exceeded ZAR 3.50. Generally, protein yield was the most important trait, although volume, longevity and SCS were more important in some situations. Calving interval was the least important trait, its value ranging from 4% to 22% of protein yield, although the model may have underestimated its value. Further work should focus on facilitating the wide adoption of these breeding objectives by industry.
    South African Journal Of Animal Science 07/2014; 44(3):199. DOI:10.4314/sajas.v44i3.1 · 0.35 Impact Factor
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