EFFECTS OF SEX AND GENOTYPE ON MORPHOMETRIC TRAITS OF RABBIT

A total of one hundred (100) matured rabbit of 4 – 6 month of age comprising of New Zealand White (NZW) and Dutch (DUT) breeds were used in the study. They comprised of forty nine (49) New Zealand White, thirteen (13) males and thirty six (36) females, Fifty one (51) Dutch breed comprising of twenty one (21) males and thirty (30) females. The experiment was conducted at the Livestock Teaching and Research Farm, University of Maiduguri, Borno State. Maiduguri. The management system used was intensive system and semi intensive system. By housing them in a cage based on breed and sex. Each rabbit is housed in a cage measuring 33cm x 38cm x 45cm and the cages were tagged for easy identification, measurement and weighing. The cages were slightly raised above the ground for cross ventilation and to facilitate cleaning.Body weight was measured with a digital weighing scale in kilograms and the body measurements were measured using tailor tape calibrated in centimeters. The data measured are body weight (BW), body length (BL), nose to shoulder length (NSL), heart girth (HG), height at withers (HW), ear length (EL), leg length (LL), tail length (TL) and height of the rabbit (HR). Results obtained showed that sex had no significant effect on all the morphometric data measured. Significant effect of genotypes on morphometric traits were observed on NSL, HG, HW, EL and TL with their corresponding values of 10.83, 13.57, 13.37, 14.73, 10.95 in Dutch breed and corresponding values in New Zealand White were 10.34, 12.90, 14.30, 13.22 and 9.98 respectively. The results of the study also revealed that Dutch breed performed better than the New Zealand White in the study area.


INTRODUCTION
Rabbits can be considered as one of the several species quite suitable for meat production. They are characterized by quality protein (20 -21%crude protein) with high biological value amino acids, meat low in calories and fat, prolificacy, short gestation length, initial capital outlay is minimal, great genetic flexibility, lipids are highly unsaturated (60% of the total fatty acids), valuable animal model for biomedical research, low sodium and cholesterol level and it is considered a delicacy for health food products (Dalle, 2002).
There are numerous breeds and varieties of rabbit all over the world varying in types of coat colors and sizes. A breed name depends on location or place of origin, color of coat, breeder nomenclature or size (Aduku and Olukosi, 2000). Medium and heavy breeds weigh about 4.1 -5.5 kg and 5.9 -7.3 kg respectively while small breeds weigh about 1.4 -1.8 kg at maturity (Aduku and Olukosi, 2006). Common breeds of rabbits found in Nigeria are New Zealand white, Californian white, and chinchilla. However, almost all of the rabbits found in Nigeria are crosses, among these, the most common exotic and next common exotic breeds in Nigeria are New Zealand White and chinchilla Aduku and Olukosi, ( 2006) other breeds not common in Nigeria according to Ekpenyong, (2008) are champagne D Argent, Dutch, Checkered giant, Florida white and white pearl.
The male progenies recorded highest values of BW (359.09+72.69) and they also recorded the highest values for morphometric body measurements. Generally, at 4 weeks Cross bred DUT X NZW recorded the highest value of BW and Ologbose et al. (2017) reported the mean standard error of Dutch(DUT)New Zealand White (NZW) and Dutch X New Zealand White (DUT X NZW). Female progenies from DUT X NZW recorded the highest body weight (BW) (347.92+67.81) and likewise for all the morphometric body measurements (MMBs) while, MBMs while NZW recorded least values of BW (234.09+77.68) and MBMs. The cross bred (DUT X NZW) indicated superiority over the pure bred at the pre-weaning ages, this observation was in line with the reports of Odubote and Somade (2008) and Chineke et al. (2000) that pre-weaning growth performance of crossbred rabbits were significantly higher than those of purebreds.Body measurements provide good report on performance, productivity and carcass quality of animals (Ige et al. 2006). Biometric measurements allow comparisons of growth in different parts of the body (Abdullah et al. 2003).Morphometric measurements have been found useful in contrasting size and shape of animals (Ajayi et al., 2008). The objective of the study is to evaluate the effects of sex and genotype on the morphometric traits of rabbit.

EXPERIMENTAL SITE
The experiment was conducted at the Livestock Teaching and Research Farm, University of Maiduguri, Borno State. Maiduguri, the state capital is located within the sahelian (semi -arid) region of West Africa on latitude 11 o 50' North and longitude 13 o 09' East and at altitude of 354m above sea level.

MANAGEMENT OF EXPERIMENTAL STOCK
A total of one hundred (100) matured rabbits of 4 -6 months of age comprising of New Zealand White (NZW) and Dutch (DUT) were used for the study. The Dutch are fifty one (51) with twenty one (21) male and thirty (30) females while the New Zealand White are forty nine (49) with thirteen (13) males and thirty six (36) females. The rabbits were sourced from two different places: one from University of Maiduguri Livestock Teaching and Research Farm Borno State and the other one were sourced from a reputable small holder's farm within Maiduguri Metropolitan council. The rabbits in the Livestock Teaching and Research Farm were managed intensely by housing them based on breed and sex. Each rabbit is housed in a cage measuring 33cm x 38cm x 45cm and the cages were tagged for easy identification, measurement and weighing. The cages were slightly raised above the ground for cross ventilation and to facilitate cleaning. Plastic drinkers (cups) and metallic feeding troughs were provided in each cage. The feeds and fresh clean water were provided ad -libitum including fresh grasses as well as fresh vegetables were used during the study. The other rabbits sourced from reputable farmers were managed under semi intensive management system. This may be as a result of feeding to reduce cost of feeding.

DATA COLLECTION
Data were collected on body weight (BW), body length (BL), nose to shoulder length (NSL), heart girth (HG), height at Withers (HW), ear length (EL), leg length (LL), tail length (TL) and height of rabbit (HR). Body weight was measured with a digital weighing scale in kilograms and the body measurements were measured using tailor tape calibrated in centimeters. Height of the rabbit: This was measured asthe distance from the ground to the back bone by using graduated measuring stick.

STATISTICAL ANALYSIS
The data collected were subjected to analysis of variance and the means separation was done using Duncan's multiple range tests. The statistical tool used was SAS version 2000. Pearson's correlation was used to analyze the association between body weight and the morphometric traits

EFFECT OF SEX ON MORPHOMETRIC MEASUREMENTS OF TWO BREEDS OF RABBIT
The effect of sex on morphometric measurement is presented in table 1. The result of the study indicated that there was nonsignificant different (p>0.05) between sex on morphometric traits studied. The present study findings do not agreed with the investigation obtained by Odubote and Somade (2008), Chineke et al. (2000) and Sam et al. (2020) who reported a significant (p<0.05) different between sex and morphometric measurements of rabbits. These may be due to heterosis, which is an indication of non-additive genes for growth traits. Abdullah et al. (2003) reported superior performance of male New Zealand White over females of other breeds, and observed that the difference could be partly attributed to the possession of major genes that improved growth.

EFFECT OF GENOTYPE ON THE MORPHOMETRIC TRAITS OF TWO BREEDS OF RABBIT
The effect of breed on morphometric measurements of rabbit is presented in  (Oke et al., 2011, Obasi et al., 2019and Sam et al., 2020.

CONCLUSIONS
The results of the present study revealed non significant (p>0.05) different observed between sex and morphometric measurements. The nonsignificant difference in traits between both sexes may be as a result of tandem. But there is significant (p<0.001) variation among breeds and morphometric traits studied. Variation among different genetic groups may be due to the genetic makeup of rabbits that influence the growth rate and may translate into higher body weight in one breed than the other.