Responses to repeated cycles of water restriction in lactating Shami goats

Morphophysiological Responses of the Goat Mammary Gland to Water Scarcity in Arid and Semi-Arid Environments: Are They Enough to Generate Adaptation to New Climatic Challenges?

Due to climate change, diverse territories of the planet will suffer from water restrictions. Goats are perceived as the most resilient ruminants in this scenario. So, various studies have focused on describing how a lower water intake influences milk production, especially in breeds adapted to desert environments. In water-stress situations, goats lose up to 32% of their body weight (BW), the rate of passage is reduced, and the digestibility of the feed increases. When goats consume water again, the rumen prevents hemolysis and osmotic shock from occurring. Regarding milk production, the response varies depending on the breed and the level of water restriction, maintaining the milk volume or reducing it by up to 41%. Systemically, it decreases the urinary volume and glomerular filtration rate, increasing blood osmolality and the vasopressin (ADH) concentration. Studies are scarce regarding changes in blood flow to the mammary gland, but there would be a reduction in blood flow velocity of up to 40% without changing blood pressure. New studies must be undertaken to determine which breeds or crosses are the best adapted to changing environmental conditions and to improve our understanding of the changes that occur at the morphophysiological level of the caprine mammary gland.

Drinking water intake, milk production, and grazing behaviour of alpine dairy goats in response to daytime water restriction on temperate pastures

Certain local breeds of goats have adapted to severe water restriction in arid and semi-arid regions, but little is known about the adaptability of high-producing dairy goats to water restriction while grazing under temperate conditions. The aim of this study was to assess effects of water restriction of lactating Alpine goats during the daytime at pasture (8 h/d) on herd-level drinking water intake and individual milk production and grazing time. Goats remained in the barn between evening and morning milkings, where each animal was offered 600 g of concentrate and 400 g of hay each day, with free access to water. Twenty four goats were used in a crossover design, for two consecutive 14-d periods. The study was conducted in early summer, with a daily mean ambient temperature of 18.2 ± 3.5 °C (range of 13-27 °C over all the study days), a mean temperature-humidity index of 64 ± 4.9 (range of 56-76). Goats had access to a high-quality multispecies pasture with a mean of 216 ± 44 g DM/kg fresh matter. Total drinking water intake averaged 5.57 L/d and did not differ significantly between treatments. Goats with water access at pasture drank a mean of 1.88 L of water per day during the grazing period, but drank 2.24 L less per day in the barn than goats without water access at pasture. Drinking water intake increased by 0.57 L per day for each °C increase in daily mean ambient temperature. Daily milk production, milk composition, body weight, and daily grazing time did not differ between treatments. Only the duration of the first morning meal at pasture differed significantly between treatments. Thus, water restriction for 8 h per day during grazing periods does not seem to influence the variables measured for Alpine dairy goats under temperate conditions.

Performance, Body Water Balance, Ingestive Behavior and Blood Metabolites in Goats Fed with Cactus Pear (Opuntia ficus-indica L. Miller) Silage Subjected to An Intermittent Water Supply

This study evaluated the performance, body water balance, ingestive behavior and blood metabolites in goats fed with cactus pear silage subjected to an intermittent water supply. Thirty-six goats were distributed in a randomized block design arranged as a 3 × 3 factorial with cactus pear silage in the goats’ diet (on a 0%, 21% and 42% dry matter-DM basis) and water offer frequency (ad libitum, and 24 and 48 h water restrictions). There was an interaction only between the cactus pear silage level and water offerings for drinking water. Goats fed 42% cactus pear silage had greater intake of non-fibrous carbohydrates, energy, Ca, Mg and Na minerals, water intake, urinary water excretion, body water retention and nutrient digestibility. Cactus pear silage inclusion up to a 42% rate reduced eating and ruminating time and increased the time spent idling as well as the eating and the ruminating efficiency rate. Water restriction at 48 h reduced drinking water intake. Performance and blood metabolites were not affected by cactus silage inclusion or water offering. Cactus pear silage inclusion at up to 42% for goats is recommended during periods of water shortage in semiarid and arid regions because it improves eating, the ruminating efficiency rate, and body water retention; cactus pear silage inclusion at this rate reduces water consumption and it does not affect the performance or health of the animals.