Effect of dietary energy on digestibilities, rumen fermentation, urinary purine derivatives and serum metabolites in Tibetan and small‐tailed Han sheep

Abstract

Tibetan sheep are indigenous to the Qinghai–Tibetan Plateau, graze the grassland all year round without supplementation and are well‐adapted to the harsh conditions. Small‐tailed Han sheep were introduced to the plateau and are raised mainly in feedlots. Based on their different backgrounds, we hypothesized that the ability to cope with poor diets would be better in Tibetan than in Han sheep. To test our prediction, we examined the effect of dietary energy on apparent digestibilities, rumen fermentation, urinary purine derivatives and serum metabolites by using a 4 × 4 Latin square design in each sheep breed. Four diets were formulated to be low in crude protein (~7%) but to differ in metabolizable energy concentration. Average daily gain was greater in Tibetan than in Han sheep (p < 0.01) and increased linearly with an increase in energy intake (p < 0.001). The digestibilities of dry matter, organic matter, gross energy, and neutral and acid detergent fibres were greater in Tibetan than in Han sheep (p < 0.05). Ruminal pH was lower (p < 0.05), while volatile fatty acids (VFAs), urea‐N, ammonia‐N and soluble protein‐N concentrations were higher (p < 0.05) in Tibetan than in Han sheep. As a molar proportion of total VFA, acetate decreased (p < 0.001) with an increase in dietary energy whereas propionate and butyrate increased (p < 0.05). Urinary purine derivative excretion was greater in Tibetan than in Han sheep (p < 0.01), as was microbial nitrogen production; both parameters increased with dietary energy (p < 0.01). Serum concentrations of glucose, insulin and insulin‐like growth factor‐1 increased (p < 0.05) as energy level increased, while non‐esterified fatty acids and growth hormone decreased (p < 0.05). It was concluded that Tibetan sheep were better able to cope with low‐protein, low‐energy diets and, consequently, our prediction was supported.

A comparison of average daily gain, apparent digestibilities, energy balance, rumen fermentation parameters, and serum metabolites between yaks (Bos grunniens) and Qaidam cattle (Bos taurus) consuming diets differing in energy level

“…In addition, the size of the rumen relative to omasum was found to be larger in yaks than in lowland cattle, which prolonged the rumen retention time in yaks ( Wiener et al., 2003 ). The apparent digestibilities of NDF and ADF decreased linearly in both yaks and cattle as the dietary energy increased, which was consistent with a study in Tibetan sheep ( Zhou et al., 2019 ), but not with crossbred steers ( Hales et al., 2014 ). In the current study, the digestibilities of DM, OM, CP and EE increased linearly with increasing dietary energy level, which was generally in agreement with results in steers ( Navarrete et al., 2017 ), dairy cows ( Su et al., 2017 ), and sheep ( Jing et al., 2019 ).…”

Comparison of rumen bacterial communities between yaks (Bos grunniens) and Qaidam cattle (Bos taurus) fed a low protein diet with different energy levels

“…However, the concentrations in both bovine species consuming the 6.62 and 8.02 MJ ME/kg DM diets were below the optimal range of 5 to 25 mg/100 mL ( Preston and Leng, 1987 ), which suggests reduced activities of fibrolytic bacteria. The ammonia-N concentration increased linearly with increasing energy level, which indicated increased protein degradability and more N available for rumen microbial production, although the N intake was similar for all energy levels ( Zhou et al, 2019 ).…”

“…available for rumen microbial production, although the N intake was similar for all energy levels (Zhou et al, 2019).…”

Gluconeogenesis Alteration and p53-SIRT6-Fox01 Signaling Adaptive Regulation in Sheep from Different Grazing Periods

“…In this present study, the concentration of propionate, isobutyrate, valerate, and isovalerate were significantly decreased while acetate was increased in sheep from the dry grass period compared to those of the green grass period. The study showed that high-energy diets could cause a reduction in acetate concentration in the rumen fluid [ 27 ]. These results demonstrated that the effects of different grazing periods on glucose metabolism might be due to the disruption of gluconeogenesis.…”