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

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.

Relationship between primiparas first 100-days lactation and their lifetime milk production in Polish Holstein-Friesian Cattle

“…The phenotypic correlations between AFC and milk yield were very small and negative (−0.05). It is in accordance with other studies in which AFC and milk yield were estimated as small and negative (−0.20 to −0.09) (Ruiz-Sánchez et al, 2007;Ojango and Pollott, 2001;Nilforooshan and Edriss, 2004). However, Teke and Murat (2013) reported the moderate positive correlation between AFC and milk yield (r = 0.32; P<0.001).…”

“…The oldest primiparas were briefly used for milk production, which influenced their lifetime performance. Age at first calving determines the beginning of the cow's productive life and influences it's lifetime productivity (Ojango and Pollott, 2001). Ojango and Pollott (2001) and Ruiz-Sánchez et al (2007) indicated that earlymaturing heifers were better milk producers.…”

“…Age at first calving determines the beginning of the cow's productive life and influences it's lifetime productivity (Ojango and Pollott, 2001). Ojango and Pollott (2001) and Ruiz-Sánchez et al (2007) indicated that earlymaturing heifers were better milk producers. According to Hoffman (1997) calving at less than 22 month of age had a negative influence on milk yield.…”

Genetic and environmental variance and covariance parameters for some reproductive traits of Holstein and Jersey cattle in Antioquia (Colombia)

“…These values were higher than those reported by Ojango and Pollott (2001) and Kadarmideen et al (2000). Nevertheless, some authors (Estrada-León et al, 2008;M'hamdi et al, 2010;Ríos-Ultrera et al, 2010a) report higher repeatability values (0.120-0.180).…”

Dairy production systems and the adoption of genetic and breeding technologies in Tanzania, Kenya, India and Nicaragua

“…Smallholder systems of dairy production in Kenya have been extensively characterized under the Smallholder Dairy Development Programme (ILRI, 2004). Large-scale commercial farms operating in the country as either dairy or dual-purpose units have also been described (Kahi, 2000;Ojango and Pollott, 2001). These systems are highly mechanized, tend to raise pure-bred exotic (B. taurus) breeds, and produce large quantities of dairy products to which they add value.…”