This study was conducted to genetically and environmentally characterize prolificacy (litter
size and weight at birth; LSB and LWB and litter size and weight at weaning; LSW and
LWW, respectively), milk yield at the 7th (MY7), 15th (MY15), 30th (MY30), 60th (MY60), 90th
(MY90) day of lactation and monthly milk yield (MMY) and milk composition traits in
Egyptian Zaraibi goats. A total of 443 and 421 records produced by 121 Zaraibi lactating
goats were used to assess prolificacy and milk production traits, respectively. The milk composition
traits were measured using 371 milk samples obtained at random from 53 goats.
The fourth parity showed the highest values for LWB, LWW, and MMY (3.62, 18.15, and
28.99 kg, respectively). Milk composition traits revealed an inverse tendency, decreasing until
the second month and then increasing until the seventh month. The heritability estimates
ranged from 0.07 to 0.13, from 0.04 to 0.39, and from 0.07 to 0.33 for prolificacy, milk yield,
and milk composition traits, respectively. Negatively high genetic correlations between MMY
and all milk composition traits were found. MMY had the highest estimate of heritability
(0.39 ± 0.07), this means that the genetic improvement of this trait could be achieved
through direct selection. |
