Effects of genetic and environmental factors on pre-weaning and post-weaning growth in West African crossbred sheep.
Effects of genetic and environmental factors on pre-weaning and post-weaning growth were studied in West African crossbred sheep. Effects of lamb genotype (7/8 Sahelian-1/8 Djallonké, 3/4 Sahelian-1/4 Djallonké and 1/2 Sahelian-1/2 Djallonké; hereafter denoted 7/8Sa, 3/4Sa and 1/2Sa, respectively), parity, type of birth, sex of lamb and year-season of lambing on birth weight, weaning weight, 8-month weight and pre- and post-weaning growth rates were determined. At birth 7/8Sa and 3/4Sa lambs were heavier (p < 0.01) than 1/2Sa lambs. Lambs born to first-parity ewes were lighter (p < 0.01) at birth than lambs of older ewes. At weaning and 8 months of age, lambs born to fourth-parity ewes were heavier (p < 0.05) than those born to ewes of the other parities. Parity did not have any significant effects on pre-weaning growth rate. Lambs born in the rainy season of 2001 were significantly heavier at birth and at 8 months of age than those born in the dry season of 2001/02, but there was no difference between the two groups at weaning. Pre-weaning growth rate was significantly faster in lambs born in the dry season of 2001/02 but the reverse was true for post-weaning growth rate.
Benyi
K
K
Department of Animal Science, Mafikeng Campus, Northwest University, Mmabatho, South Africa.
Norris
D
D
Karbo
N
N
Kgomo
K A
KA
D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology; D000818:Animals; D001835:Body Weight / Q000235:genetics* / Q000502:physiology; D003433:Crosses, Genetic; D004777:Environment; D005260:Female; D008297:Male; D010298:Parity; D011247:Pregnancy; D012621:Seasons; D012737:Sex Factors; D012756:Sheep / Q000235:genetics* / Q000254:growth & development*; D014886:Weaning