Supplementing a ruminally undegradable protein supplement to maintain essential amino acid supply to the small intestine when forage intake is restricted in beef cattle1

Abstract

Twelve Angus crossbred cattle (eight heifers and four steers; average initial BW = 594 +/- 44.4 kg) fitted with ruminal and duodenal cannulas and fed restricted amounts of forage plus a ruminally undegradable protein (RUP) supplement were used in a triplicated 4 x 4 Latin square design experiment to determine intestinal supply of essential AA. Cattle were fed four different levels of chopped (2.54 cm) bromegrass hay (11.4% CP, 57% NDF; OM basis): 30, 55, 80, or 105% of the forage intake required for maintenance. Cattle fed below maintenance were given specified quantities of a RUP supplement (6.8% porcine blood meal, 24.5% hydrolyzed feather meal, and 68.7% menhaden fish meal; DM basis) designed to provide duodenal essential AA flow equal to that of cattle fed forage at 105% of maintenance. Experimental periods lasted 21 d (17 d of adaptation and 4 d of sampling). Total OM intake and duodenal OM flow increased linearly (P < 0.001) as cattle consumed more forage; however, OM truly digested in the rumen (% of intake) did not change (P = 0.43) as intake increased. True ruminal N degradation (% of intake) tended (P = 0.07) to increase linearly, and true ruminal N degradation (g/d) decreased quadratically (P = 0.02) as intake increased from 30 to 105%. Duodenal N flow was equal (P = 0.33) across intake levels, even though microbial N flow increased linearly (P < 0.001) as forage OM intake increased. Total and individual essential AA intake decreased (cubic; P < 0.001) as forage intake increased because the supply of nonammonia, nonmicrobial N flow from RUP was decreased (linear; P < 0.001) by design. Total duodenal flow of essential AA did not differ (P = 0.39) across these levels of forage intake. Although the profile of essential AA reaching the duodenum differed (P < or = 0.02) for all 10 essential AA, the range of each essential AA as a proportion of total essential AA was low (11.1 to 11.2% of total essential AA for phenylalanine to 12.3 to 14.3% of total essential AA for lysine). Duodenal essential AA flow did not differ (P = 0.10 to 0.65) with forage intake level for eight of the 10 essential AA. Duodenal flow of arginine decreased linearly (P = 0.01), whereas duodenal flow of tryptophan increased linearly (P = 0.002) as forage intake increased from 30 to 105% of maintenance. Balancing intestinal essential AA supply in beef cattle can be accomplished by varying intake of a RUP supplement.

Effects of early- to mid-gestational undernutrition with or without protein supplementation on offspring growth, carcass characteristics, and adipocyte size in beef cattle1

“…The mitrient-restricted (NR) diet was 70% of NE," and GP provided by the Gon diet. The nutrient-restricted -I-protein-supplemented (NRP) diet was 70%) of NE," provided by the Gon diet plus a RUP supplement (6.8% porcine blood meal, 24.5% hydrolyzed feather meal, and 68.7% menhaden fish meal; DM basis; Scholljegerdes et al, 2005) to provide duodenal essential AA fiow equivalent to the Gon diet (Scholljegerdes et al, 2004). Diet composition and daily intakes are shown in Table 1.…”

“…It has previously been reported that AA stimulate protein synthesis and muscle growth acting through mammalian target of rapamycin signaling (Zhu et al, 2004;Han et al, 2008). A protein supplement has been developed that can be fed to supply the intestine of a beef cow the same quantity of essential A A, even when she is experiencing restricted forage intake (Scholljegerdes et al, 2005). The objective of this study was to understand the impacts of maternal imdernutrition and protein supplementation during early and mid gestation on offspring growth, adipocyte size, and expression of nutrient transporters and transcription factors in steer and heifer offspring slaughtered at normal production endpoints.…”

Small intestinal growth measures are correlated with feed efficiency in market weight cattle, despite minimal effects of maternal nutrition during early to midgestation1

“…Minerals and vitamins were added to the CON and NR diets to provide intake similar to the NR+RUP treatment (Table 1). The RUP supplement (68.7% menhaden fish meal, 24.5% hydrolyzed feather meal, and 6.8% porcine blood meal, DM basis), designed by Scholljegerdes et al (2005b), was provided to match the duodenal AA flow of CON using the following equation: total essential AA flow to the small intestine (g/d) = (0.055 × g of OM intake) + 1.546 (Scholljegerdes et al, 2004). This was also adjusted to account for increased RUP supplement degradation in feed-restricted cattle (Scholljegerdes et al, 2005a).…”

Supplementation of molasses and branched-chain amino acid to increase in vitro digestibility of ammoniated corn cob in ruminants feed

“…Therefore amino acid composition of feed protein is important for ruminant animals. Methionin, lysine, fenylalanin and threonine were amino acid needed by ruminants (Scholljegerdes et al 2005). Other amino acid also needed by ruminants were valin, isoleusin, dan leusin (Volden 1999;Zain 2007).…”