CHARACTERIZATION OF LITTER MORTALITY IN STRAIGHTBRED NEW ZEALAND WHITE RABBITS

Document Type : Original Article

Authors

1 Animal Breeding and Production, Fac. Vet. Med., Alex. Univ., Edfina

2 Animal and Poultry Behavior and Management, Fac. Vet. Med., Alex. Univ., Bostan Branch

Abstract

Eight hundred sixty six kits of 104 New Zealand White litters were studied for the rate of stillbirth, within litter mortality (M) between birth and day 21 of age (M0-21) where kits rely solely on milk, day 22 to weaning (M22-28) and postweaning to marketing (M29–70). Overall least squares means were 6.96% (stillbirth), 10.62% (M0-21), 0.55% (M22-28) and 3.08% (M29-70). In 30.77% of litters, all kits survived to marketing. Dead kits at birth and those died within the first week of age had significantly (P 60g). Kit survival pre- (M0-21) and postweaning (M29-70) was better when their does gained > 250 g bwt during the first three weeks post-kindling compared to dams losing bwt or gaining < 250 g. The rate of stillbirth increased (P = 0.06) with longer gestation periods. M0-21 was higher (14.39 vs 6.86%, P< 0.05) in large litters (≥ 9 alive kits vs < 9 kits). Summer and spring born litters experienced higher (P<0.05) M0-21 (14.98 and 14.27%) than autumn (7.42%) and winter (5.81%) born ones. Parity affected only stillbirth (P<0.05) with litters of the 1st, 2nd and ≥ 3rd orders lost 5.83, 4.98 and 10.07% of their kits at birth, respectively. Repeatability estimates were generally low (0.00 to 0.07) except for a moderate value of 0.31 for M0-21. It could be concluded that stillbirth and M0-21 are the major components of kit losses. Small kit size, dam bwt loss or low bwt gain during the first three weeks postnatal, large litters, summer and spring kindlings, and 3rd or higher kindling orders reduced kit survival, particularly at birth and during the first three weeks of age.

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Kafrelsheikh Veterinary Medical Journal
Volume 6, Issue 2
October 2008
Pages 210-228

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