Submitted to: Western Section of Animal Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2010
Publication Date: July 15, 2010
Citation: Mulliniks, J.T., Muscha, J.M., Lodge-Ivey, S.I., Petersen, M.K. 2010. Predicted mineral intake utilizing both water and forage analysis varies by source and location of livestock water in Eastern Montana. Western Section of Animal Science Proceedings 88(E-Suppl. 2):685. Abstract #W309. Technical Abstract: Circulating serum glucose concentrations as well as glucose utilization have been shown to be affected by forage quality. Supplemental protein provided to grazing range cows while consuming low quality forage may improve glucose metabolism. The objective of our study was to determine the effects of winter protein supplement strategy on serum glucose half-life, insulin response, as well as identify the effects of previous gestational protein supplementation on mid lactation milk yield. The study was conducted two consecutive calving seasons utilizing 5-yr old Angus and Angus crossbred cows (n = 8/trt each yr, 530 kg average BW). Cows were supplemented until calving with 1) a control 36% CP (35% UIP of CP) cottonseed meal based cube (CON), hand-fed at 454 g/d delivered 3d/wk ($16/45.4 kg), or 2) a self-fed 50:50 loose mineral and fishmeal 33% CP (60% UIP of CP) small supplement (SSP), formulated for a targeted consumption of 113g/d ($52/45.4 kg). After calving, cows were supplemented similarly (CON at 908 g/d offered 3 d/wk). Supplemental protein source affected (P = 0.03) glucose half-life, whereby the SSP cows had a lower half-life compared to CON (62 and 85 min respectively). Supplement also influenced insulin area under the curve (AUC; P < 0.01) with CON having a larger area compared to the SSP treatment (95.18 ± 4.9 and 75.02 ± 4.8 respectively). Prepartum glucose AUC (P = 0.10) and insulin half-life (P = 0.75) were unaffected by supplement treatment. Milk yield or components was not affected (P > 0.05) by supplement; however year showed a significant (P < 0.05) effect on these parameters. Milk yield was decreased from 7531 g ± 299 in yr 1 to 4328 g ± 293 in yr 2, possibly due to lower forage quality (~3% CP vs. ~8% CP in yr 1). These results suggest that supplemental undegradable intake protein, during times of low quality forage, may improve glucose clearance.