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 nеgаtivеs. 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.

Genetic parameters, phenotypic and genetic trends of litter size on different breeds of goats in Egypt.

Data of 475 goats (242 Zaraibi, 84 Baladi, and 149 Damascus) kept at Sakha Farm, belonging to Animal Production Research Institute (APRI), Ministry of Agriculture, Dokki, Cairo, Egypt, from the period of 2011 to 2017 were used to estimate direct (additive) and maternal genetic effects for litter size at birth (LSB). Three animal models were used. Model 1 includes the fixed effects of breed, season, year of kidding, age of doe, and direct genetic effect. Model 2 is similar to model 1 beside the permanent environmental effect. Model 3 is similar to model 2 and includes the maternal genetic, covariance between direct and maternal genetic effects. The effects of breed, season, year of kidding, and age of doe were significant on LSB. Heritability estimates for LSB are 0.19±0.050, 0.19±0.160, and 0.06±0.007, as estimated from models 1, 2, and 3, respectively. Maternal heritability estimate using model 3 was 0.05±0.006. The removal of additive genetic maternal effect and covariance between direct and maternal effects from the model increased heritability of direct genetic effect by 0.13. Annual phenotypic trends for LSB in Zaraibi, Baladi, and Damascus goat breeds are negative. Annual genetic trends for LSB for the three breeds of goats are positive, significant, and being 0.10±0.01, 0.25±0.02, and 0.01±0.001 litter/year for Zaraibi, Baladi, and Damascus, respectively. The present results indicated that selection for LSB will take a long time. The speed and efficiency of selection is expected to increase by use of molecular markers in selection.

Genetic evaluation of semen traits in Friesian bulls raised in Egypt.

A total of 14696 semen records were collected from Friesian bulls, kept at International Livestock Management Training Center belonging to Animal Research Institute, Ministry of Agriculture, Dokki, Cairo. Traits studied were volume, motility, livability and sperm concentrates in other to construct selection indexes by using all combination between different traits of semen to improve semen traits in a herd of Friesian bull cattle. Data were analysed by using four traits repeatability model and includes effects of the following fixed factors: the age of animal at semen collection, the combined effect of the month and year of semen collection, and the number of times semen were collected per month. Semen motility, volume and livability were highly influenced (p < 0.001) by all the fixed factors. Heritability estimates for semen traits were moderate and ranged from 0.29 to 0.33. All phenotypic and genetic correlations between different traits are positive and ranged from 0.09 to 0.67 for phenotypic correlations and from 0.02 to 0.68 for genetic correlations, while permanent environmental correlations ranged from -0.69 to 0.12. Estimated Breeding Values ranged from -0.68 to 0.78 ml for semen volume, from -13.17 to 7.34% for motility, from -259.42 × 10-6 to 239.64 × 10-6 for concentrates and from -6.83 to 6.09% for livability. Eleven selection indexes were calculated, selection Indexes not including livability showed a reduced accuracy. This study demonstrated that selection index (I3) which includes sperm volume, motility and livability or selection index (I8) which includes sperm volume and livability are the best and both are recommended for Friesian bulls' selection.