Effects of type and quality of roughage and energy level on plasma progesterone levels in pregnant goats

Abstract

Norwegian dairy goats ( n = 188) were fed either barn dried hay, good quality silage from tower silos or poor silage from aerobically deteriorated round bales ad libitum plus 400 g concentrate kg −1 milk for the first 90 days of gestation or to the end of lactation. From Day 91 to Day 120 of pregnancy, goats were fed either only roughage to 70% of maintenance energy requirement or were fed roughage ad libitum plus 100 g concentrate per doe per day. From Day 121 of pregnancy until kidding all the goats were given 200 g barn dried hay, good silage ad libitum and 900 g concentrate per goat (12.5% DCP) daily. Goats fed silage of poor quality had a significantly lower ( P < 0.01) plasma progesterone level compared to those fed hay or good silage during the first 90 days of pregnancy. Plasma progesterone level was lower ( P < 0.01) in goats fed to 70% of maintenance energy requirement than in those fed roughage ad libitum with supplementation of concentrate between 91 and 120 days of gestation. A lower ( P < 0.05) plasma progesterone level was found in goats fed poor silage compared with those fed good silage or hay at low energy levels during this period. Goats in which pregnancy terminated in abortion had lower ( P < 0.01) plasma progesterone level during gestation, compared with normal goats. Plasma progesterone decreased rapidly to nearly zero at the time of abortion and remained low after abortion. Plasma progesterone level was higher ( P < 0.01) in goats with multiple foetuses than in those carrying a single foetus. It was concluded that plasma progesterone level was affected by nutrition during pregnancy and was related to reproductive performance.