Performance of Friesian, Jersey and Their Crosses under Smallholder Dairy Production Systems in Tropics: A Meta Analysis

Abstract

Crossbreeding effects of Friesian (FR) and Jersey (JY) breeds for dairy development in the tropics were reviewed. A meta-analysis was performed based on the results of 90 crossbreeding studies carried out in tropics from 1963 onwards. Least squares means (LS) for milk yield (MILK), lactation length (LACL), age at first calving (AFC) and calving interval (CI) of the crosses were compared to study the relationship between the dairy characters and the proportion of exotic breed genes. Breed substitution (ADD) and heterosis effects (HET) of both breeds were estimated. The LS means for the purebred indigenous (IND), FR and JY breeds, respectively, were 962 (± 34), 2788 (± 39) and 1822 (± 43) kg for MILK, 241 (± 5), 323 (± 6) and 322 (± 6) days for LACL, 1316 (± 20), 975 (± 21) and 928 (± 21) days for AFC and 458 (± 7), 455 (± 7) and 427 (± 8) days CI. The ADD of FR and JY were highly significant (p≤0.001), being 1421 (± 100) and 802 (± 102) kg for MILK, 79 (± 9) and 68 (± 13) days for LACL, -204 (± 39) and -337 (± 66) days for AFC and 13 (± 9) and -31 (± 12) days for CI, respectively. The HET of FR and JY were 434 (± 64) and 305 (± 61) kg for MILK, 35 (± 6) and 23 (± 9) days for LACL, -121 (± 19) and -101 (± 23) days for AFC and -23 (± 5) and -27 (± 7) days for CI, respectively. The MILK of the F1 cross of both breeds was 25% higher than that of F2, which indicates a larger recombination loss than expected under the greek temple model of heterosis. The FR crosses gave higher milk yield over longer lactation length than JY crosses. However, the JY crosses calved earlier and continued their calving at shorter intervals than FR counterparts.