Abstract

Food deprivation leads to diminished water intake and decreased milk production in lactating goats. The aim of this study was to determine whether these effects could be alleviated by offering six lactating goats (Capra hircus) warm water to drink at normal or hot ambient temperatures. The food deprivation period was started on Day -1 at 0700 h by feeding the goats hay but no concentrates. No food was then given until 1515 h on Day 0. Between 0700 and 1800 h on Day 0 water was supplied to the goats in three different ways at different ambient air temperatures as follows: (1) cool (15 degrees C) water in one bucket and warm (35 degrees C) water in another (cool-warm water experiment); (2) cool (15 degrees C) water in two buckets (cool-cool water experiment); and (3) warm water in one bucket and cool water in the other in combination with a hot ambient temperature from 1045 h to 1700 h (heat-stress). Experiments 1 and 2 were performed at room temperature (17.5-19 degrees C) and at a relative humidity of 60-70%. In Experiment 1, the goats drank 0.7 +/- 0.61 of the cool water and 5.0 +/- 1.21 of the warm water before re-feeding (P < 0.001). In Experiment 2, the goats drank 1.5 +/- 0.61 of the cool water. In Experiment 3, they drank more warm water (4.1 +/- 0.81) than cool water (0.51 +/- 0.21; P < 0.001). Body weight decreased in all experiments during Day -1. It decreased further on Day 0 in Experiment 2, but not in Experiment 1, and in Experiment 3 the goats regained their pre-starvation body weight. The milk lactose concentration fell by 10 and 11 mmol l(-1) in Experiments 1 and 2, respectively (P < 0.001, afternoon Day -2 compared with afternoon Day 0), but only by 2 mmol l(-1) in Experiment 3 (NS). The mean milk K concentration decreased by 7, 8 and 4 mmol l(-1) in Experiments 1, 2 and 3, respectively. The milk Na concentration did not change in any of the experiments. Milk osmolality did not change despite the drop in milk lactose and K concentrations. Food deprivation reduced milk flow in all experiments, which resulted in decreased secretions of lactose and protein in all experiments. The fat secretion did not decrease significantly during the heat-stress experiments. It is concluded that offering warm instead of cool drinking water to food-deprived lactating goats increased their water consumption and that this, in combination with heat stress, counteracted the reduction of the milk secretion. (C) 1997 Elsevier Science B.V.

Keywords

food deprivation; goat; heat stress; milk secretion; water intake

Published in

Small Ruminant Research
1997, volume: 25, number: 1, pages: 69-75

Authors' information