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ARS Home » Plains Area » Mandan, North Dakota » Northern Great Plains Research Laboratory » Research » Publications at this Location » Publication #184899
Title: EFFECT OF RESTRICTED INTAKE OF RUMINAL DISAPPERANCE OF BROMEGRASS HAY AND A BLOOD MEAL, FEATHER MEAL, AND FISHMEAL SUPPLEMENT

Author
item Scholljegerdes, Eric
item LUDDEN, PAUL - UNIVERSITY OF WYOMING
item HESS, BRET - UNIVERSITY OF WYOMING

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2005
Publication Date: 9/8/2005
Citation: Scholljegerdes, E.J., Ludden, P.A., Hess, B.W. 2005. Effect of restricted intake of ruminal disapperance of bromegrass hay and a blood meal, feather meal, and fishmeal supplement. J. Anim. Sci. 83:2146-2150

Interpretive Summary: Two experiments were conducted to determine the rate of ruminal disappearance of bromegrass hay and a ruminally undegradable protein (RUP) supplement in beef cattle fed restricted amounts of forage. Six Angus-cross cattle (Body weight = 589 ± 48.1 kg) fitted with ruminal cannulas were fed chopped (2.54 cm) bromegrass hay (8.9% CP) at one of three percentages of maintenance intake (30%, 55%, 80%). In both experiments, the cattle were allowed 7 d for diet adaptation followed by 3d of sample collection. In Exp 1, nylon in situ bags (50-µm pore size) containing 4.1 g of bromegrass hay (OM basis) were inserted into the rumen and subsequently removed at 3, 6, 9, 12, 15, 18, 24, 36, and 48 h after insertion. Statistical models were used to determine protein fractions A and B and protein degradation rate. Intake level did not affect forage protein remaining after ruminal incubation or protein fractions A, B, and C. However, effective ruminal degradation of hay protein tended to increase as forage intake increased. In Exp 2, 4.2 g of an RUP supplement (6.8% blood meal, 24.5% feather meal, and 68.7% fish meal) formulated to provide equal amounts of protein to the small intestine across all levels of hay consumption was evaluated in a similar manner as in Exp 1. The undegraded protein fraction of the supplement was not different across treatments at 3, 6, 9, and 18 h. However, increasing forage intake resulted in a linear increase in undegraded protein remaining at 12, 15, 24, 36 and 48 h. Dietary treatment had no affect on protein fractions A, B, or C; however, protein degradation rate of the supplement declined linearly (P = 0.03) as forage intake increased. Therefore, effective ruminal degradation of the supplement decreased linearly from 50.8 to 40.9% as forage intake increased from 30 to 80% of maintenance. Corresponding estimates of supplement RUP were 49.2, 56.5, and 59.1% for the 30, 55 and 80% of maintenance intake treatments, respectively. Restricting dietary intake can reduce the quantity of dietary protein that escapes ruminal degradation. Therefore, tabular estimates of RUP may not be appropriate for formulating diets to balance protein in beef cattle limit-fed forage.

Technical Abstract: Two experiments were conducted to determine in situ disappearance of bromegrass hay and a ruminally undegradable protein (RUP) supplement in beef cattle fed restricted amounts of forage. Six Angus-cross cattle (BW = 589 ± 48.1 kg; n = 3 steers and n = 3 heifers) fitted with ruminal cannulas were fed chopped (2.54 cm) bromegrass hay (8.9% CP) at one of three percentages of maintenance intake (30%, 55%, 80%). In both experiments, the cattle were allowed 7 d for diet adaptation followed by 3d of sample collection. In Exp 1, in situ bags (50-µm pore size) containing 4.1 g of bromegrass hay (OM basis) were inserted into the rumen and subsequently removed at 3, 6, 9, 12, 15, 18, 24, 36, and 48 h after insertion. Non-linear regression models were used to determine protein fractions A and B and protein degradation rate. Intake level did not affect (P = 0.15 to 0.95) forage protein remaining after in situ incubation or protein fractions A, B, and C. However, effective ruminal degradation of hay protein tended to increase quadratically (P = 0.12) as forage intake increased. In Exp 2, 4.2 g (OM basis) of an RUP supplement (6.8% blood meal, 24.5% feather meal, and 68.7% fish meal) formulated to provide equal amounts of metabolizable protein across all levels of hay consumption was evaluated in a similar manner as in Exp 1. The undegraded protein fraction of the supplement was not different (P = 0.16 to 0.74) across treatments at 3, 6, 9, and 18 h. However, increasing forage intake resulted in a linear increase (P ÿ 0.06) in undegraded protein remaining at 12, 15, 24, 36 and 48 h. Dietary treatment had no affect (P = 0.30) on protein fractions A, B, or C; however, protein degradation rate of the supplement declined linearly (P = 0.03) as forage intake increased. Therefore, effective ruminal degradation of the supplement decreased linearly (P = 0.01) from 50.8 to 40.9% as forage intake increased from 30 to 80% of maintenance. Corresponding estimates of supplement RUP were 49.2, 56.5, and 59.1% for the 30, 55 and 80% of maintenance intake treatments, respectively. Restricting dietary intake can reduce the quantity of dietary protein that escapes ruminal degradation. Tabular estimates of RUP may not be appropriate for formulating diets to balance metabolizable protein in beef cattle consuming limited quantities of forage.