Effect of inbreeding on growth and reproduction traits of Beetal goats (short communication)
Abstract. Level of inbreeding and its effects on growth and reproductive traits were measured in Beetal goats using 4554 kidding records (1968–2004) from an experiment station in Pakistan. Level of inbreeding varied over the years; was zero in 1974 then increased 0.42% per year till 1987 when all the bucks and some of the does were replaced with unrelated animals. From 1988 till 2000, inbreeding again increased 0.21% per year and declined thereafter due to introduction of unrelated bucks. The average level of inbreeding over the years varied from zero to 7.3%. 42.7 % of all investigated animals were inbred, half of which had inbreeding greater than 6.25%. About 3.4% of animals were 25% or more inbred. Regression analysis indicated that birth weight (p<0.05), weaning weight (p<0.01) and pre-weaning daily gain (p<0.01) had improved in inbreds while post-weaning daily gain (p<0.01) deteriorated. Deterioration in weight at first service and at first kidding did not reach statistical significance. Kidding interval increased (p<0.01) due to inbreeding. Within inbreds, however, decline due to inbreeding was observed for birth, weaning and yearling weight but slopes were not different from zero, statistically. Rate of decline in weight at first service and at first kidding however, was different from zero (p<0.01). Effect of inbreeding on growth and reproductive traits in Beetal goats was not very pronounced in the flock. Planned matings are however, suggested to avoid accumulation of inbreeding and appearance of its deleterious effects.