EFFECT OF PARITY ON LITTER SIZE AT BIRTH AND AT WEANING IN RABBITS
Background of the Study
Owing to the increasing cost of animal protein sources in the developing Nations, leading to animal protein deficiency especially in Nigeria, it will be wise for farmers to embark on the production of livestock species which will give high protein turn over within a short period interval. Rabbit, a mini livestock fits into this description. All these benefits can be annexed with effective breeding programme such as selection of animals from reputable does and this should not be approached half hazardly. It should be done from litters in parities that have proven to perform outstandingly. This study was therefore carried out to evaluate the effect of parity on litter size at birth and weaning in order to identify parities with higher litters. Selection on litter size has had a lower than expected success as a consequence of its low heritability ( Baselga, 2004). A reduction in the environmental variance of litter size would increase the heritability and consequently its response to selection. Besides, homogeneity in litter size reduces cross-fostering, facilitating management with a consequent reduction of costs. Pre-weaning mortality is a major cause of wastage in rabbit production. Filiz et al. (2009) stated that birth weight variation within litters affects kits survival and weight gain. Parity and litter size are some of the factors affecting birth weight. Milligan et al. (2002) indicated that parity influences birth weight and generally, does in first parity kindled litters with lower birth weight than does in other parities. Litter size at birth increases as parity increases. Yamani et al. (1991) reported that effect of parity on litter size at birth did not show any consistent trend. Litter size at weaning increased as parity advanced up to the sixth one. The differences in this character due to parity were significant (P ≤ 0.01). Ouyed and Brun (2008) reported that rabbits from second parity were heavier at weaning (0.69 kg) and had the highest commercial carcass weight. This was in agreement with the result reported by Prayaga and Eady (2003). Litter size, parity and birth weight are some of the factors affecting survival rate. Higher litter size may cause elevation in mortality rate in first 10 days (Filiz et al., 2009). Recent studies have reported evidences for an additive genetic control of environmental variance on litter size (Sorensen and Waagepetersen, 2003) in pigs; (Gutiérrez et al., 2006) in mice and in uterine capacity; (Ibañez-Escriche et al., 2007) in rabbits, and in litter weight at birth (Garreau et al., 2004, in rabbits). According to Armero et al. (1995), litter size at birth and weaning have been the traits of choice to select specialized dam line. Parity have been reported to affect litter size which thus suggest that at some parities, litter size will be better than others.
Objectives of the Study
The objectives of this study are therefore:
- To determine the body weight of rabbits from different parities
- To determine the relationship between litter size and parity.