ORIGINAL ARTICLE: Effects of ambient temperature and soybean meal supplementation on intake and digestion of two sheep breeds differing in mature size

Abstract

The aim of this study was to compare the intake and digestive physiology of mature ewes of two breeds--Ile-de-France (mature weight: 75-80 kg) and Churra-da-Terra-Quente (CTQ; mature weight: 45-50 kg)--and evaluate the effects of ambient temperature and protein supplementation in the comparison. The temperature (25 °C vs. 11 °C) and soybean meal supplementation (150 g/kg of ingested hay on dry matter basis vs. unsupplemented control) were evaluated in 48 adult ewes of two breeds fed hay ad libitum and at a restricted level of intake. The intake, digestibility, rumen pH and NH(3)-N, rumen outflow rates, faeces particle size and thyroid hormones levels were measured. These hormones can be related with gastrointestinal motility, thus explaining rumen outflow rate patterns. Dry matter intake per kg of body weight was higher in CTQ ewes (p < 0.05). This breed also exhibited lower organic matter and neutral detergent fibre digestibility (p < 0.001) and higher solid (p < 0.001) and liquid (p < 0.01) rumen outflow rates irrespective of intake level, supplementation or temperature. Rumen pH remained above 6.6 in all treatments. NH(3)-N rumen content was similar (p > 0.05) when breeds were fed only hay. There was no breed effect (p > 0.05) on faeces particle size. Triiodothyronine was not affected (p > 0.05) by breed and thyroxine was higher (p < 0.10) in the CTQ breed but only at the lower temperatures (breed × temperature, p < 0.05). Ile-de-France sheep showed a lack of adaptation to lower temperatures. This study suggests that the native CTQ breed fulfils its metabolic needs by having a higher intake and inherits faster flow through the gastrointestinal tract, as a result, its digestive ability is diminished.

Low ambient temperature elevates plasma triiodothyronine concentrations while reducing digesta mean retention time and methane yield in sheep

“…() reported similar results using cattle with weights inserted into the rumen to measure effect of ruminal distension on MRT and MY while Lourenço et al. () recorded no temperature effect on apparent digestibility when exposing two different breeds of sheep to different diets and ambient temperatures. This suggests that exposing animals to low ambient temperatures may cause an improvement in the efficiency of utilisation of dietary energy.…”

Thermoregulatory responses related to coat traits of Brazilian native ewes: an adaptive approach

“…These hormones have thermogenesis capacity and play an important role in certain physiological functions related to growth, reproductive efficiency and dairy production (West 2003;Al-Haidary 2004). The animals exposed to thermal stress conditions can reduce these hormones when the air temperature increases sharply (Todini et al 2007;Helal et al 2010;Lourenço et al 2010;Maurya et al 2010).…”

Comparative digestibility of low‐quality grass hay by two breeds of cattle differing in mature live weight

“…When the ewes were compared, at the same degree of maturity and given similar levels of feeding, the rate of passage of feed particles was approximately 90% faster in Churra than in Ile‐de‐France (Lourenço et al., ). This result was later confirmed with mature animals and at the same level of intake (Lourenço et al., ). It is not known whether, and to what extent, the same digestive feature, that is, a higher rumen outflow rate, has been developed by Barrosão cattle, whose female mature weight is also approximately 60% of its Holstein–Friesian breed counterpart.…”

“…Previous comparisons made in our laboratory with growing and mature sheep fed mixed diets and cereal straw or hay supplemented with a protein source, showed that the ability to digest fibre was also higher in the improved Ile‐de‐France breed than in the native Churra breed (Lourenço et al., , ; Gomes, ). These two breeds differ largely in mature weight, with the LW of the Churra breed being approximately 60% of that of the Ile‐de‐France one.…”