Abstract
ObjectiveThe objectives of the current study were to study the main environmental factors affecting birth weight (BW) and weaning weight (WW), estimate variance components, genetic parameters and genetic trend and to evaluate the variability and relationships among breeding value of BW and WW using principal components analysis (PCA).MethodsA total of 16,370 records were collected from 8,271 buffalo calves. Genetic parameters and breeding values were estimated using a bivariate animal model which includes direct, maternal and permanent maternal effects. These estimates were standardized and used in PCA.ResultsThe direct heritability estimates were 0.06 and 0.41 for BW and WW, respectively whereas direct maternal heritability values were 0.03 and 0.14, respectively. Proportions of variance due to permanent environmental effects of dam were 0.455 and 0.280 for BW and WW respectively. The genetic correlation between BW and WWs was weak approaching zero, but the maternal correlation was 0.26. The first two principal components (PC1 and PC2) were estimated utilizing the standardized breeding values according to Kaiser method. The total variance explained by the first two PCs was 71.17% in which 45.91% and 25.25% were explained by PC1 and PC2, respectively. The direct breeding values of BW were related to PC2 but those of WW and maternal breeding values of BW and WWs were associated with PC1.ConclusionThe results of genetic parameters and PCA indicate that BW and WWs were not genetically correlated and improving growth traits of Egyptian buffaloes could be achieved using WW without any adverse effect by BW.
Highlights
Water buffalo are important source of meat, high quality milk and skin as well as other by products, in Egypt and in many countries worldwide
The calves having gestation length between 260 to 310 days had the heaviest birth weight (BW), followed by those having gestation length longer than 325 days whereas the calves having gestation length below 296 days were the lightest BW. These results were in agreement with what reported in other studies on beef cattle by Jamrozik and Miller [15], where they found a positive genetic correlation between BW and GL
The current study found a significant (p
Summary
Water buffalo are important source of meat, high quality milk and skin as well as other by products, in Egypt and in many countries worldwide. Buffalos contribute significantly in agriculture economy and human well-being in these regions. The total num ber of buffaloes worldwide is about 195.1 million heads, in which 97% are raised in Asia [1] and 2% (~4 million head) are reared in Egypt [1] mainly for milk and meat production. Known as river buffalo (Bubalus bubalis) contributed 39.2% and 45.2% of national total meat and milk production, respectively [1]. As 96% of buffaloes popula tion in Egypt are owned by small holders, buffaloes play an essential role in rural economy and have challenges in establishing genetic improvement program. MMI Salem and AMS Amin [2] showed that the stillbirth incidence was similar in either light
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