Abstract
ObjectiveThe present study was carried out to evaluate the effect of high dietary cation and anion difference (DCAD) rations on diurnal variations in eating and meal patterns, water intake and urination patterns in dairy goats fed under high ambient temperature (HTa).MethodsTen crossbred dairy goats during peri-parturition period were selected and divided into two groups of five animals each. Experimental diets were control DCAD (control, 22.8 mEq/100 g dry matter [DM]) and high DCAD (DCAD, 39.1 mEq/100 g DM). The composition of two diets consisted of 44% corn silage and 56% concentrate. From the 2nd week to 8th week postpartum, goats were fed ad libitum twice daily either with the control or DCAD total mix ration with free access to water. The spontaneous eating and drinking patterns were determined.ResultsThe environmental conditions in the present experiment indicated that goats were fed under HTa conditions (average peak THI = 85.2) and were in heat stress. In addition to the typical HTa induced tachypnoea in both groups, the respiratory rate in the DCAD group was significantly higher than the control group (p<0.05). Although the goats from both groups showed comparable level of eating, drinking and urination during experiment, the meal pattern and water intake were different. High DCAD apparently increased eating and meal patterns compared with the control. At week 8 postpartum, goats from high DCAD group had significant (p<0.05) bigger meal size and longer meal duration. Moreover, high DCAD appeared to increase night-time water intake (p<0.05).ConclusionBoth meal pattern and night-time drinking effects of DCAD suggested that feeding with high DCAD ration may alleviate the effect of heat stress in dairy goat fed under HTa conditions.
Highlights
In tropical countries, dairy animals are confronted with prolonged high ambient temperature (HTa) during prolonged summers
The data reported here revealed the effect of dietary high dietary cation and anion difference (DCAD) on eating, drinking and urination behaviors in crossbred dairy goats fed under HTa condition
The higher night-time water intake (WI) and the non-significant difference of milk yield and urine volume apparently contributed to evaporative heat dissipation during day time. It was clear from the environmental conditions and animal responses (Tr and respiration rate (RR)) reported in the present experiment that all goats were fed under HTa condition and were at the stage of heat stress [6,22]
Summary
Dairy animals are confronted with prolonged high ambient temperature (HTa) during prolonged summers. Decreased feed intake and increased water intake (WI) during HTa have been reported in both dairy cattle and goat [1,2,3]. Supplementation with high dietary cation and anion difference (DCAD) by increasing sodium and potassium in both species increased both WI and dry matter intake (DMI) as reported by previous studies [7,8]. It was well accepted that goats fed under HTa have different mechanisms and tolerance compared with cattle. Dairy cattle responded to acute heat stress by increasing respiration rate and body temperature [12, 13] and altering the rumen function [14]. Because goats were considered more tolerant to HTa condition compared with cattle, and because our previous results suggested that supplemented with DCAD increased water balance and influence body fluid distribution [15]. We were interested on the effect of DCAD in relation to eating and drinking behaviors and planed the present study which aimed at investigating the potential effect of higher DCAD to alleviate the HTa effect on diurnal variations in feed intake, WI, and urination patterns
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