- Differences in ruminal and blood metabolites between goats and sheepgrazing two different pastures
|Last update: August 15, 2011 08:34:15 AM|
Differences in ruminal and blood metabolites between goats and sheep grazing two different pastures
M J Herselman*, T Sahlu & S P Hart
E (Kika) de la Garza Institute for Goat Research,
Langston University, Langston, OK, USA
It has been reported that several hormones are associated with adaptation of small stock breeds to different environments. Most adaptational problems can be solved by supplementary feeding, therefore the objective of this study was to investigate ruminal and blood metabolites and to relate it to voluntary feed intake. Angora and Spanish goats and sheep (Suffolk x Rambouillet crossbreds) grazed mature Old World Bluestem grass (Bothriochloa caucasica) or native range with a wide variety of high quality herbage for 46 days prior to sampling. Ruminal acetic, propionic, butyric, iso-butyric, valeric and iso-valeric acids were higher in sheep (P<0.01) than goats on both pastures. Ruminal acetate: propionate ratio in Angora goats was lower (P<0.05) than in Spanish goats and sheep on native range only. Plasma NH3-N was lower (P<0.01) in Spanish goats, plasma glucose was lower (P<0.01) in Angora goats and plasma urea-N was higher (P<0.01) in sheep when compared with the other breeds on both pastures. Concentration of serine in plasma of Angora and Spanish goats and sheep was 305, 79 and 59 mmol/l respectively on Old World Bluestem pasture and 306, 140 and 115 mmol/l on native range. Plasma glycine concentrations for the respective breeds were 1042, 451 and 621 mmol/l on Old World Bluestem pasture and 797, 857 and 620 mmol/l on native range. Plasma alanine concentration was higher (P<0.05) in Angora goats on Old World Bluestem pasture and methionine concentration in Angora goats was lower (P<0.05) than the other breeds on both pastures. Fecal output for Angora and Spanish goats and sheep was 12.5, 19.3 and 19.6 g/kg0.75/d respectively on Old World Bluestem pasture and 19.6, 20.3 and 23.4 g/kg0.75/d on native range. These results indicate that adaptation problems, normally associated with high fibre producing animals, like Angora goats, are related to low voluntary feed intake. Ruminal metabolites may merely reflect differences in feed intake and diet selection, while plasma metabolites may be indicative of metabolic adjustments to compensate for decreased nutrient absorption from the gastro-intestinal tract.
Proceedings 33rd SASAS congress