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ARS Home » Southeast Area » Booneville, Arkansas » Dale Bumpers Small Farms Research Center » Research » Publications at this Location » Publication #66833
Title: NET FLUX OF NUTRIENTS ACROSS SPLANCHNIC TISSUES IN WETHERS CONSUMING AD LIBITUM DIFFERENT PROPORTIONS OF BERMUDAGRASS AND RYEGRASS-WHEAT

Author
item Goetsch, Arthur
item PATIL, A - UNIV OF ARKANSAS
item GALLOWAY SR, D - UNIV OF ARKANSAS
item WANG, Z - UNIV OF ARKANSAS
item KOUAKOU, B - UNIV OF ARKANSAS
item PARK, K - UNIV OF ARKANSAS
item ROSSI, J - UNIV OF ARKANSAS

Submitted to: Archives of Animal Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Little information exists regarding differences between tropical and temperate grasses in fate or efficiency of metabolism of absorbed nutrients, particularly with grass mixtures, which along with intake and digestibility dictate level and efficiency of performance. Therefore, objectives of this experiment were to determine effects of dietary proportions of tropical and temperate grasses (i.e., 0, 33, 67 and 100%) on net flux of oxygen and nutrients across the portal-drained viscera, liver and splanchnic bed in growing wethers with ad libitum consumption. As a percentage of digestible energy intake, energy used by the splanchnic bed increased linearly as digestible energy intake declined. Thus, performance of growing ruminants consuming low-quality grass appears limited not only by low intake and(or) digestibility but also is restricted by a relatively high proportion of absorbed energy used by splanchnic tissues. Furthermore, factors in addition to physiological workload, as depicted by intake of digestible energy, may influence the quantity of energy consumed by the splanchnic bed and seem deserved of study.

Technical Abstract: Crossbred wethers (18, 7.5 mo of age and 31 +/- 0.8 kg) were used in a 23-d experiment to determine effects of ad libitum consumption of diets differing in proportions of coarsely chopped bermudagrass hay (B) and ryegrass-wheat hay (0, 33, 67 and 100%) on net flux of nutrients across the portal-drained viscera (PDV), liver and splanchnic bed. Bermudagrass and ryegrass-wheat were 9 and 13% crude protein and 78 and 71% neutral detergent fiber, respectively. Intake of dry matter (1.03, 0.92, 0.92 and 0.76 kg/d), digestible energy (3.22, 2.56, 2.52 and 1.97 Mcal/d) and digestible nitrogen (12.8, 8.7, 7.6 and 5.2 g/d for 0, 33, 67 and 100% B) changed linearly and cubically (P<0.05) as B level increased. Consumption of oxygen by the PDV tended to decrease linearly (P=0.14) with increasing B (182, 154, 156 and 137 mM/h), and hepatic oxygen consumption decreased linearly (P<0.05) and changed cubically (P=0.07; 150, 113, 116 and 103 mM/h for 0, 33, 67 and 100% B, respectively). However, splanchnic tissue energy consumption as a percentage of digestible energy intake increased linearly (P=0.08) with increasing B (24.0, 27.6, 28.6 and 33.2% for 0, 33, 67 and 100% B, respectively). Release of alpha-amino nitrogen by the PDV was similar among treatments (25.9, 21.0, 22.4 and 18.9 mM/h; SE 3.09), and hepatic urea nitrogen release changed linearly (P<0.05) and quadratically (P=0.08) as dietary B increased (43.5, 31.7, 21.5 and 24.1 mM/h for 0, 33, 67 and 100% B, respectively). In conclusion, the proportion of absorbed energy utilized by the splanchnic bed may vary with characteristics of forage being consuming ad libitum and, thus, influence ruminant performance.