The use of adapted breeds, such as Santa Inês, is of paramount importance for regions with high temperatures because they develop efficient mechanisms for heat dissipation. Furthermore, some breeds have physiological adaptations, such as more efficient mechanisms for the digestion of fibrous foods (e.g. Rabo Largo), which can reduce the harmful effects of semiarid environments. We studied the ingestive behaviour, water consumption, and physiological parameters during feeding of two native sheep breeds fed diets containing high (700 g/kg DM; HC diet) or low (300 g/kg DM; LC diet) percentages of concentrates, based on dry matter (DM). A total of 40 uncastrated male lambs (20 Rabo Largo [breed 1] and 20 Santa Inês [breed 2], with an average body weight of 16.68 ± 2.78 kg, and 19.29 kg ± 3.28 kg, respectively), were distributed in a randomised block design in a two-by-two factorial scheme (breeds × diets) with 10 repetitions. Santa Inês lambs consumed and ruminated DM (P = 0.029 for both) and neutral detergent fibre (NDF; P = 0.001 and P = 0.004, respectively) more efficiently than RaboLargo lambs, while the latter showed an increase in respiratory rate (+19 breaths/min) and rectal temperature (+1.3 °C) compared to the Santa Inês lambs (P = 0.001). The HC diet negatively affected (P < 0.05) the feeding behaviour of the animals, reflecting the higher (P < 0.05) water consumption. The results showed that diets rich in concentrate negatively affected the thermoregulation of lambs. Santa Inês have greater feed and thermoregulatory efficiency than Rabo Largo lambs under conditions of heat stress in the feedlot.
Twenty eight crossbred Boer goat kids (21.6 ± 3 kg BW) were used in a randomized complete block design to evaluate the effects of increasing levels (0, 10, 20 and 30%, DM basis) of babassu mesocarp flour (BMF) on feeding behavior and physiologic parameters. Goat kids were individually confined and fed an isonitrogenous diet (12.6 ± 0.1 CP) containing 70% concentrate and 30% Tifton hay (DM basis) for 58 d, with 12 d for diet adaptation and 46 d for experimental period. Animals were monitored every 5 min during 24 h, on the 23th and 44th days of the experiment, according to the activities: eating, rumination, idle and other activities. The feed and rumination efficiencies, expressed as g DM/hour were obtained by dividing the average daily intake of DM by the total time spent eating and/or ruminating in 24 h, respectively. The animals’ physiological responses were evaluated at 06:00; 10:00; 14:00 and 18:00 h, over 10 consecutive experimental days, in which the following parameters were measured: rectal temperature (RT), body temperature (BT) and respiratory rate (RR). Orthogonal polynomials for diet responses were determined by linear and quadratic effects. Effects were declared significant at P ≤ 0.05. The levels of BMF did not affect (P ≥ 0.05) the time spent in eating, idle, rumination (averaging 217±27.4, 363±17.2 and 859±30.6 min/d, respectively), feed efficiency of DM (averaging 245±32.3 g DM/h), rumination efficiency of DM and NDF (averaging 138±28.1 and 155±26.6 g/h respectively) and RR (averaging 54±3.9 mov/min). However, the efficiency of feeding NDF, RT and BT increased linearly with BMF (P < 0.05). It is concluded that BMF can be added up to 30% in the diet of goat kids and despite the increase in some of physiological variables, there was no thermal stress, confirmed by the absence of differences in feeding behavior.
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