Effect of type of roughage and energy level on reproductive performance of pregnant goats

Abstract

Wilted grass silage of good quality from tower silos, silage of poor quality from aerobically damaged round bales, or barn-dried grass hay was used as the roughage component of the diet fed to 188 goats over 2 years. The goats were fed roughage ad libitum plus 400 g concentrate kg −1 milk for the first 90 days of gestation. From Day 91 to Day 120 of pregnancy they received either roughage ad libitum with supplementation of 100 g concentrate per goat day −1 or were fed only roughage to 70% of maintenance energy requirement. From Day 121 of pregnancy until kidding the feed consisted of 200 g hay, good silage ad libitum and 900 g concentrate per animal day −1. Reproductive losses were significantly higher ( P < 0.01) in goats fed silage of poor quality compared with those fed hay or good silage in both experiments. Low energy feeding between Day 91 and Day 120 of pregnancy caused an increase ( P < 0.01) in the rate of abortion in goats fed poor silage. Reproductive losses were lowest and number of kids born per goat after normal pregnancy were highest in goats fed good silage, irrespective of the energy level. Listeria monocytogenes was identified as the cause of abortion in five of the 43 goats that aborted. The rate of abortion was higher in older than in younger goats. Feeding silage of poor quality combined with low energy in the period of 91–120 days of gestation increased the rate of abortion in goats. Underfeeding with roughage of good quality during the same period had no influence on the rate of abortion.