Estimating Additive and Dominance Variance for Litter Traits in Purebred California White Kits Using Different Models

Reproductive and growth records of 82 purebred California white kits were used to estimate additive and dominance genetic variances using BULPF90PC-PACK. Estimates were obtained for litter size at birth (LSB) and at weaning (LSW); litter weight at birth (LWB) and at weaning (LWW); individual kit weight at birth (IKWB)and at weaning (IKWW)as well as neonatal (Nil) and morlality at weaning (WM). Two mixed model equations were adopted. The first model included fixed effects and random effects identifying inbreeding depression, additive gene effect and permanent environmental effects. The second model was similar to the first model, but included the dominance genotypic effect. Estimates of heritability from sire component of variance for LSB, LSW, LWB, LWW, IKWB and IKWW were 0.4810.53,0.41/0.44, 0.5010.55 ,0.491NA, 0.4410.47 and 0.48/0.56 from model 1 and 2 respectively. Proportions of dominance effect to total phenotypic variance from the dominance model were 0.222, 0.453, 0.206, 0.349, 0.417 and 0.521 for LSB, LSW, LWB, LWW, IKWB and IKWW respectively. Dominance effects, which are not transferable through gametes (haploid entities) but are recreated at random in the offspring, were found to influence the litter traits analyzed. Therefore, genetic evaluation with the dominance model (Model 2) was found more appropriate than the animal model (Model 1). Keywords: Additive, Dominance, Heritability, Inbreeding, Rabbi

Genetic and Non Genetic Sources of Variation for Linear Body Conformation Traits in Bunaji and Friesian X Bunaji cows

The effects of Age of dam at calving, Sex of calf, Breed, Sire, month of calving and season of lactation on linear body conformation traits was investigated in the dairy herd of the National Animal Production Research Institute, Shika Zaria, Nigeria. Seven linear body conformation traits of 25 Bunaji and 25 crossbred (Friesian x Bunaji) cows were measured. The measurements were taken monthly by 3 evaluators for the complete lactation length of the cows, this resulted in 1275 cumulative records, (with 750 records from Friesian x Bunaji and 525 records from Bunaji). The 7 body conformation traits (stature, chest width, wither height, heart girth, body length, body depth and rump width) were measured in centimeter using flexible tape. The results showed that all the genetic and non genetic factors considered had significant effect (P<0.05) on the linear body conformation traits. However, there was no significant (P>0.05) variation amongst the evaluators in their measurements, except RW. The body size characteristics increased with age. The male bearing cows were relatively broader (CW, HG) and longer (BL) than the female bearing cows, though there was no significant difference (P>0.05) in their statures (ST) and the body depth (BD). The crossbred cows were taller (ST, HW) longer (BL), broader (CW, HG), but less deep (BD) than the pure Bunaji. The animals of season 1 were taller (ST, WH), deeper (BD) and longer (BL) than the others. However, animals of season 2 and 3 had similar body sizes (ST, CW, BD, WH, HG, BL and RW). It is therefore suggested that in selecting for body conformation these genetic and non genetic factors should be taken into consideration.Key words: Friesian x Bunaji, linear body conformation, evaluators, breed, sir

Genetic and Non-Genetic Factors Affecting Litter Size and Birth Weight of Rabbit in Minna, Niger State, Nigeria

. Genetic and non-genetic factors influencing litter size and birth weight of rabbit was evaluated using New Zealand White and Chinchilla breeds. Parameters measured were total number of kittens born per litter, number of litter born alive, live litter birth weight and average litter birth weight. Results of the experiment revealed that dam breed had no significant affect on total number of kittens born per litter, number of litter born alive and average litter birth weight while live litter birth weight were affected. Sire breed and month of birth did not significantly influenced all the parameters measured. Heritability estimates were low to moderate for all the traits (0.27 to 0.44), while repeatability estimates were observed to be low (0.17 to 0.26). No heritability and repeatability values were estimated for average litter birth weight of kittens due to negative genetic variance. Significant correlations were found between litter size traits and birth weight. Correlation between litter size traits and average litter birth weight, as well as live litter birth weight and average litter birth weight were observed to be non-significant

Relationship Between Gestation Length and Birth Weight in Nigerian Sheep and Their Crosses

Effect of genotype and birth weight on gestation length was evaluated using Nigerian breeds of sheep and their crosses. The study was carried out at the Sheep Project Unit of Small Ruminant Research Programme (SRRP) of National Animal Production Research Institute (NAPRI), Ahmadu Bello University, Shika-Zaria. The sheep breeds used were Balami, Uda and Yankasa. Heat (estrus) detection was carried out twice daily; in the morning (07:00-08:00 hours); and in the evening (16:00-17:00 hours) using apron fitted rams to pick does on heat. A total of 56 lambs were used for this study. The data obtained were subjected to analysis of variance using General Linear Model and Correlation Procedure of SAS. All the genotypes had similar gestation length with values between 150.3±0.61 days and 153.3±0.60 days, except for Balami pure breed (BAL X BAL) lambs that recorded a shorter gestation length (137.1±0.81 days). There was a wide variation in the birth weight of lambs with the crosses between Balami rams and Yankasa ewes recording a distinct birth weight of 3.5±0.08 kg while the crosses obtained using Yankasa rams on Uda and Balami ewes gave the lowest birth weights (1.7±0.19 and 1.4±0.18, respectively). Sex and litter type have no significant effect (P>0.05) on gestation length. Birth weight was however affected by sex of lambs and their litter type. Litter type was negatively correlated with birth weight (-0.372). Gestation length had a low and non-significant relationship with birth weight; litter type and lamb genotype. Lamb genotype does not have a significant relationship with litter type. Genetic improvement of Nigeria sheep breed is possible if the resources of within and between breed is exploited. Selection for a reduction in gestation length may indirectly increase prolificacy. (Animal Production 12(3): 135-138 (2010)Key Words : gestation length, birth weight, Nigerian Shee

Relationship Between Gestation Length and Birth Weight in Nigerian Sheep and Their Crosses

Effect of genotype and birth weight on gestation length was evaluated using Nigerian breeds of sheep and their crosses. The study was carried out at the Sheep Project Unit of Small Ruminant Research Programme (SRRP) of National Animal Production Research Institute (NAPRI), Ahmadu Bello University, Shika-Zaria. The sheep breeds used were Balami, Uda and Yankasa. Heat (estrus) detection was carried out twice daily; in the morning (07:00-08:00 hours); and in the evening (16:00-17:00 hours) using apron fitted rams to pick does on heat. A total of 56 lambs were used for this study. The data obtained were subjected to analysis of variance using General Linear Model and Correlation Procedure of SAS. All the genotypes had similar gestation length with values between 150.3±0.61 days and 153.3±0.60 days, except for Balami pure breed (BAL X BAL) lambs that recorded a shorter gestation length (137.1±0.81 days). There was a wide variation in the birth weight of lambs with the crosses between Balami rams and Yankasa ewes recording a distinct birth weight of 3.5±0.08 kg while the crosses obtained using Yankasa rams on Uda and Balami ewes gave the lowest birth weights (1.7±0.19 and 1.4±0.18, respectively). Sex and litter type have no significant effect (P>0.05) on gestation length. Birth weight was however affected by sex of lambs and their litter type. Litter type was negatively correlated with birth weight (-0.372). Gestation length had a low and non-significant relationship with birth weight; litter type and lamb genotype. Lamb genotype does not have a significant relationship with litter type. Genetic improvement of Nigeria sheep breed is possible if the resources of within and between breed is exploited. Selection for a reduction in gestation length may indirectly increase prolificacy. (Animal Production 12(3): 135-138 (2010

Genetic and Relationship Estimations of Body Weight and Morphometric Traits in the Red Sokoto Goat

Data on body weight (BW) and body measurements of 1000 Red Sokoto kids comprising 570 males and 430 females collected from smallholder herds in Kano, Nigeria, were used to evaluate the genetic and relationships estimates amongst growth traits. The records were taken at birth, 1, 3, 6, and 9 months of age for body weight, height-at-wither (HW), body length (BL) and chest girth (CG). Both correlation and regression analyses were carried out on the growth traits. Heritability estimates were computed using paternal half sib analysis, while the repeatability estimates were calculated using the variance components. The model used was the fixed effect of sire. The average birth weight, BW, HW, BL, and CG at 1, 3, 6, and 9 month of age were 1.8, 4.5, 7.6, 10.6, and 12.8 kg;  32.6, 40.2, 45.9, and 51.5 cm; 33.6, 40.8, 49.0, and 52.1 cm and 35.2, 43.6, 52.3, and 56.0 cm, respectively. The heritability estimates for body weight at various ages ranged between 0.91 and 0.97. The heritability estimates for body measurements were between 0.70 and 0.83, while their repeatability was between 0.70 and 0.89. Birth weight significantly (p<0.01) and positively correlated with body weight and body measurements at the different age categories (0.313-0.983) except for BL and CG at 6 month of age. A combination of HW and CG best estimated body weight in Red Sokoto kids. The high heritability and repeatability estimates for the growth traits and their positive relationships are indications that selection for improved body weight and size, early in life of these goats is possible

Effect of Genetic and Environmental Factors on Linear Udder Conformation Traits and Milk Yield in Bunaji and Friesian X Bunaji Cows

The effects of evaluators, sex of calf, breed, sire, parity, month of calving and season of lactation on linear udder conformation traits and milk yield was investigated in the dairy herd of the National Animal Production Research Institute, Shika, Zaria, Nigeria. Seven linear udder conformation traits coupled with milk yield of 25 Bunaji and 25 crossbred (Friesian x Bunaji) cows were measured between 2007 and 2008. The measurements were taken monthly by three evaluators for the complete lactation length of the cows, resulting in 1275 cumulative records, (750 from Friesian x Bunaji and 525 from Bunaji). The seven udder conformation traits; rear udder height (RUH), rear udder width(RUW), Udder-hock distance (UD), udder cleft(UC), fore teat position(FTP), rear teat placements(RTP) and teat length(TL), were measured in centimeter using flexible tape. The result showed that all the genetic and environmental factors considered had significant effect (p<0.05) on the linear udder conformation traits and milk yield. RUH, RUW, TL and milk yield increased with parity, from the 1st to the 5th parity. UD decreased with parity. The males bearing cows had larger udder size with wider teats placement (FTP and RTP) and stronger ligament (UC) than their female counterparts did. In addition, the male bearing cows had significantly (p<0.05) higher milk yield than the female bearing cows. The crosses had larger udder with strong ligament (UC) and longer teats that were further apart in front (FTP) and closer in the rear (RTP) view than the pure Bunaji. The crosses produced higher milk yield than the pure Bunaji. Milk yield was higher in early wet season (April – June), while the late dry season (January – March) had the lowest milk yield. It is therefore suggested that in selecting for udder conformation and milk yield, these genetic and environmental factors should be considered