COMPUTER-BASED PEDIGREE CHARTING AND INBREEDING EFFECTS ON PERFORMANCE TRAITS OF N’DAMA CATTLE IN FASHOLA, OYO STATE, NIGERIA

Abstract

The limited number of information usually available on farm animals in the developing countries and the need for the animal breeder to know the pedigree of individual animals in order to determine their level of inbreeding and relationship has been a most challenging task. A computer-based pedigree charting and inbreeding coefficient calculation program was developed. It was written with Nantucket Clipper (R) 5.01 and Nantucket Tools II (R) for Clipper 5.01 to take care of animals with minimal parental information peculiar to most developing countries. The program finds and saves to the disk the pedigree information to the seventh generation on all individual animal whose immediate parental information is available. The new database file is then used to calculate the inbreeding coefficient of that individual animal using Wright's formula. The speed and capacity of the computer program is basically determined by the available computer resources. Records of 4184 N'Dama calves born between 1947 and I984 at Fashola Stock Farm, Oyo State, Nigeria was used to test the efficiency and efficacy of the computer program and to determine the effects of inbreeding on some performance trails, these traits include age at first calving (AFC), average calving interval (CALINT), birth weight (CALBWT), 120-day adjusted weight (AD120D), average daily gain to 120 days (I20DG), 205-day adjusted weight (AD205D), average daily gain to 205 days (205DG), 365-day adjusted weight (AD365D) and average daily gain to 365 days (365DG). Only 273 of the 4184 calves (6.53%) were inbred with an average inbreeding coefficient (INCOEF) of 9.71%, while five out of 293 sires (1.71%) with INCOEF of 9.25% and 43 out of 1849 dams (2.33%) with INCOEF of 9.95% were inbred. The INCOEF for the entire population was 0.63%; for males the mean was 0.70% and 0.58% for females. The mean CALBWT (n=4162) was 18.86 ± 0.05kg. The effects of sex, year, season, parity, age of dam, dam's AFC and dam's INCOEF was highly significant. A percentage increase in the dam's inbreeding coefficient resulted in 65.2g decrease in calf birth weight. The mean ADI20D and I20DG (n=54) was 99.73 ± 1.95kg and 0.670 ± 0.0015kg respectively. The mean AD205D and 205DG (n=652) was 105.54 ± 0.74kg and 0.427 ± 0.0004kg respectively. The mean AD365D and 365DG (n=779) was 133.90 ± 0.88kg and 0.315 ± 0.002kg respectively. Neither the inbreeding coefficient of the calf nor that of its dam had any important influence on these traits, however, these traits were affected by sex, season and parity (P<0.05). The mean AFC (n=1756) was 40.43 ± 0.18 months and the mean CAUNT was 445.34 ± 2.68 days. The AFC of heifers was significantly affected by the heifer's level of inbreeding and a percentage rise in inbreeding level of heifers resulted in about 10 days decrease in AFC. The study shows that inbreeding was low in the N'Dama population at Fashola and that it affected only the calf's birth weight and heifer's age at first calving in N'Dama cattle. The major implications of the conclusions drawn from this study is that although the number of inbred animals in the population is relatively low, however the inbreeding level of these animals is high. This is a result of the fact that breeding policy on the farm was not strictly adhered to and the lack of proper and adequate registration system and inconsistent animal identification on the farm may be responsible for the inbreeding observed in the N'Dama population at Fashola Stock Farm.