PRINCIPAL COMPONENT ANALYSIS OF GENETIC BREEDING VALUES FOR MILK AND REPRODUCTIVE TRAITS IN FRIESIAN CATTLE IN EGYPT | ||||
| Zagazig Journal of Agricultural Research | ||||
| Volume 51, Issue 6, November and December 2024, Page 2123-2132 PDF (460.94 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/zjar.2024.403415 | ||||
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| Authors | ||||
Ali A. El-Raghi   1; A.S. Abo El-Enin2; M.A. Abu El-Hamed3
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| 1. Anim. Poult. and Fish Prod. Dept., Fac. Agric., Damietta Univ., Egypt | ||||
| 2. Anim. Prod. Res. Inst. (APRI), Agric. Res. Cent., Minist.Agric., Dokki, Giza 12619, Egypt | ||||
| 3Anim. Prod. Res. Inst. (APRI), Agric. Res. Cent., Minist.Agric., Dokki, Giza 12619, Egypt | ||||
| Abstract | ||||
| The aim of this study was to assess genetic parameters and breeding values for milk traits (total milk yield, TMY and lactation period, LP) as well as reproductive traits, including days open (DO), calving interval (CI) and age at first calving (AFC) in Friesian cattle. The study also involved analyzing the relationship between genetic breeding values using principal component analysis (PC) and constructing a selection index to improve overall performance. A dataset comprising 2837 records from 1243 cows, offspring of 108 sires and 835 dams during the period from 2000 to 2015 was collected from two experimental stations, Sakha and El-Karada, managed by the Animal Production Research Institute. The estimated heritability values were 0.29, 0.23, 0.04, 0.06, and 0.07 for TMY, LP, CI, DO, and AFC, respectively. Repeatability estimates stood at 0.30 for TMY, 0.27 for LP, 0.04 for CI, and 0.12 for DO. Among four principal components, two exhibited eigenvalues greater than 1, collectively explaining 94.05% of total variance. PC1 and PC2 accounted for 67.87% and 26.18% of the variance, respectively. Genetic index equations derived from these two PCs were formulated as follows: PCs1=0.361EBVTMY+0.446EBVLP +0.490EBVAFC+0.475EBVCI+0.453EBVDO PCs2=0.643EBVTMY+0.494EBVLP -0.178EBVAFC-0.421EBVCI-0.365EBVDO. In conclusion, PC could be utilized in genetic improvements of economic traits instead of traditional selection programs. Notably, a favorable correlation between milk production and reproductive traits was observed in the genetic index represented by PC2, suggesting its potential use in selection programs to enhance milk traits while concurrently reducing CI, DO, and AFC. | ||||
| Keywords | ||||
| Genetic parameters; principal component analysis; milk; reproductive traits; friesian cattle | ||||
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