Rumen parameters of yaks (Bos grunniens) and indigenous cattle (Bos taurus) grazing on the Qinghai‐Tibetan Plateau

Abstract

Yaks and indigenous Qaidam cattle and cattle‐yak crosses (C × Y) graze on the Qinghai‐Tibetan Plateau (QTP) throughout the year, but yaks are raised at higher elevations than cattle. Yaks do not receive supplementary feed whereas cattle require supplementary feed during harsh winter. We hypothesized that yaks would cope with the severe conditions of the QTP better than cattle and utilize the pasture more efficiently. We also hypothesized that differences between species would be pronounced in winter, when conditions are particularly harsh. To test these hypotheses, seasonal rumen fluid parameters of yaks, C × Y and cattle (n = 3 for each) were examined. Rumen fluid was collected in summer and winter from each genotype 2, 5 and 12 hr after a day of grazing. Concentrations of total volatile fatty acid (VFA), acetate, propionate, isobutyrate and isovalerate were greater in yaks than in cattle in summer (p < 0.05), while propionate concentration was lower in yaks than in cattle in winter (p < 0.05). Concentrations of ammonia and urea were greater (p < 0.001) in yaks than in cattle (p < 0.001) in summer, whereas, concentrations of free amino acids (AA) were greater in cattle than in yaks in summer and winter (p < 0.001). Concentrations of total VFA, acetate, propionate and butyrate decreased linearly (p < 0.05), whereas concentrations of isobutyrate and isovalerate increased linearly for yak and C × Y with sampling time (p < 0.05) in summer. In summer, concentrations of isobutyrate and isovalerate were greater in yaks than in cattle (p < 0.05). In conclusion, rumen fermentation characteristics of yaks showed that they coped better than cattle or C × Y in the harsh climate as we hypothesized. However, in contrast to our hypothesis, this emerged only in summer, when pasture was plentiful and not in winter, when pasture was scarce.

An increase in dietary lipid content from different forms of double‐low rapeseed reduces enteric methane emission in Datong yaks on the Qinghai‐Tibetan Plateau

“…The range in rumen pH of the yaks in the present study was relatively high when compared to cattle and was also above the optimal pH range between 6.2 and 7.2 reported for maintaining normal cellulolysis (Van Soest, 1994). In general, the pH of yak rumen fluid tends to be higher than cattle, as Shi et al (2019) reported a range between 6.82 and 7.15 and Zhou et al (2018) reported a range between 6.96 and 7.09 for yaks. High pH values (7.18-7.31) were also reported for Tibetan sheep, a ruminant well adapted to cold and high elevation (Zhou et al, 2005), and that co-exists with yaks.…”

“…In general, the pH of yak rumen fluid tends to be higher than cattle, as Shi et al. (2019) reported a range between 6.82 and 7.15 and Zhou et al. (2018) reported a range between 6.96 and 7.09 for yaks.…”

Metabolismo en rumiantes y su asociación con analitos bioquímicos sanguíneos

“…El NH3 es absorbido mediante difusión pasiva a través de los canales de ion potasio (K + ), ubicados en la membrana del rumen (García et al, 2014), por circulación portal llega al hígado donde es sintetizado en urea (Rostom y Shine, 2018). La síntesis de urea comienza en la matriz mitocondrial (Shi et al, 2019) con la unión del anión hidrogenocarbonato (HCO3 -) y el NH3, por medio de carbamoil fosfato sintetasa. El fosfato de carbamoil se une a la ornitina, por medio de ornitina transcarbamoilasa, generando citrulina.…”

“…Metabolismo de Aminoácidos en Rumiantes El metabolismo de los aa involucra la transaminación y desaminación (Dong et al, 2016), reacciones necesarias para el anabolismo y catabolismo de las proteínas (Golshan et al, 2019). Los aa Arg, histidina (His), isoleucina (Ile), leucina (Leu), lisina (Lys), metionina (Met), fenilalanina (Phe), treonina (Thr), triptófano (Trp) y valina (Val), son producidos en su mayoría por fermentación ruminal (Zhou et al, 2019). Los aa están compuestos por un grupo amino (-NH2) y un grupo COOH; además de una cadena lateral R, que les da propiedades hidrofílicas, hidrofóbicas, ácidas, básicas y aromáticas (Rostom y Shine, 2018).…”

“…Los aa están compuestos por un grupo amino (-NH2) y un grupo COOH; además de una cadena lateral R, que les da propiedades hidrofílicas, hidrofóbicas, ácidas, básicas y aromáticas (Rostom y Shine, 2018). La transaminación se lleva a cabo por aminotransferasas, el grupo -NH2 se transfiere de un aa ácido a un aa cetoácido (Zhou et al, 2019;Batista et al, 2016). Las aminotransferasas se localizan en el citoplasma y mitocondrias, teniendo dos tipos de especificidad: I) el tipo de aa que dona el -NH2 (Emery, 2015) y II) el cetoácido que acepta el -NH2 (Dong et al, 2016).…”