A comparison of several methodologies of selection index for productive and reproductive characteristics in Egyptian buffaloes

Data on Egyptian buffalo first lactation records (n = 1167) available at Mehalet Mousa Farm (between 2002 and 2015) of the Animal Production Research Institute (APRI), Cairo, Egypt, were used to analyse the genetic parameters of total milk yield (TMY), lactation time (LP), and age at first calving (AFC). Additionally, four selection indices were created by using a single phenotypic standard derivation as relevant economic values. The data were evaluated using multiple-trait derivative-free restricted maximum likelihood (MTDFREML). The estimated heritabilities for TMY, LP, and AFC were 0.22, 0.17, and 0.08 respectively and the phenotypic and genetic correlations between TMY and LP were 0.76 and 0.56, respectively, and between AFC with TMY and LP were negatives. Using a selection index that incorporates TMY, LP, and AFC (RIH = 0.68) looks to be optimum for increased genetic gain and a shorter generation interval; as a result, selection should thus be exercised near the end of the first lactation.