Influence of rumen protein degradability and supplementation frequency on performance and nitrogen use in ruminants consuming low-quality forage: cow performance and efficiency of nitrogen use in wethers2

Abstract

Two studies were conducted to determine the influence of CP degradability and supplementation frequency (SF) on ruminant performance and N efficiency. Treatments included an unsupplemented control (CON) and degradable intake protein (DIP; 82% of CP) or undegradable intake protein (UIP; 60% of CP) provided daily, every 3 d, or every 6 d. Seven wethers (36+/-1 kg BW) were used in the digestibility study with DIP and UIP treatments formulated to meet CP requirements. Eighty-four Angus x Hereford cows (512+/-42 kg BW) in the last third of gestation were used for the performance study. The DIP treatments were calculated to provide 100% of the DIP requirement and UIP treatments were provided on an isonitrogenous basis compared with DIP. Basal diets consisted of low-quality (5% CP) meadow hay. Forage DMI and N intake by lambs decreased (P < 0.05) linearly as SF decreased. Additionally, DMI, OM intake, N retention, N digestibility, and digested N retained were greater (P < 0.01) for supplemented wethers than for controls with no difference due to crude protein degradability. Nitrogen balance, DMI, and OM intake decreased linearly (P < 0.05) as SF decreased. Plasma urea (PU; mM) was measured over a 6-d period and supplemented lambs had increased (P < 0.01) PU compared with CON. Plasma urea linearly decreased (P < 0.01) as SF decreased. Pre- and postcalving (within 14 d and 24 h of calving, respectively) cow weight and body condition score change were more positive (P < 0.05) for supplemented groups than for controls. Results suggest CP supplements consisting of 20 to 60% UIP can be effectively used by ruminants consuming low-quality forage without adversely affecting N efficiency and animal performance, even when provided as infrequently as once every 6 d.

BEEF SPECIES SYMPOSIUM: An assessment of the 1996 Beef NRC: Metabolizable protein supply and demand and effectiveness of model performance prediction of beef females within extensive grazing systems1,2,3

“…Physiologically, the mature beef cow can be triggered to better capitalize on recycled N and/or AA conservation to either meet the needs or reduce the demands during times of limited nutrient supply. Data on the effectiveness of frequency of supplementation strategies for cows (Houston et al, 1999;Bohnert et al, 2002;Farmer et al, 2004a) but not heifers (Moriel et al, 2012) and on the ability of cows to adapt to environments in terms of energy use conservation (Keren and Olson, 2006a,b) also support the concept that the current 1996 Beef NRC does not adequately account for plasticity and adaptability of the mature beef cow in arid and semiarid range conditions. An improvement in the next Beef NRC would be a model that does not ignore the contribution of MP for energy needs rather than going toward lean tissue growth.…”

“…The effectiveness for alternative frequencies of protein supplementation to beef cattle consuming low-quality forage (Houston et al, 1999;Bohnert et al, 2002;Currier et al, 2004a,b,c;Farmer et al, 2004a,b;Schauer et al, 2005) indirectly implicated N recycling as an important process of N conservation in extensive grazing systems. Indeed, Wickersham et al (2008) concluded that in cattle consuming low-protein forage-based diets, N recycling played a significant role in the effectiveness of the alternative frequency of supplementation strategies.…”

The Effect of Rumen Undegradable Protein Level of Concentrate With Rice Straw as Basal Diet on Growth Performance of Sumba Ongole Beef Cattle

“…Konsumsi BK pada kedua kelompok yang sama dikarenakan kedua kelompok mengkonsumsi jerami dan konsentrat dalam jumlah yang relatif sama, dengan bahan baku dan kandungan nutrien yang relatif sama pula, hanya dibedakan pada kandungan RDP dan RUP-nya. Sesuai dengan hasil beberapa penelitian sebelumnya bahwa penambahan tingkat RUP dalam pakan tidak memberikan pengaruh nyata terhadap konsumsi BK (Diaz-Royon et al, 2016;Aboozar dan Niazi, 2013;Lopez, 2012;Duarte et al, 2011;Ali et al, 2009;Broderick et al, 2009;Richardel, 2004;Bohnert et al, 2002;Dunlap et al, 2000;Greenfield et al, 2000;Hartwell et al, 2000).…”

Recria de bezerras de corte em pastagem de azevém sob frequências de suplementação

“…A mudança na frequência de suplementação tem sido estudada internacionalmente (BOHNERT et al, 2002;LOY et. al., 2008) e pode ser uma opção eficiente para reduzir tempo, trabalho e equipamentos relativos ao fornecimento de suplementos, sem causar I Programa de Pós-graduação em Zootecnia, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brasil.…”