1) The study evaluated 107 Angus-sired calves from two sire lines - a conventional US grain-based sire (CONV) or New Zealand forage-based sire (FORAGE) - backgrounded for 45 days on starch-based or fiber-based diets then finished. 2) During backgrounding, FORAGE calves gained less initially but ended at similar weights as CONV calves. In finishing, CONV calves gained more and were heavier at harvest with heavier carcasses, larger ribeyes, and more marbling. FORAGE calves had more backfat. 3) The study found no economic advantage for calves from forage-based over grain-based Angus

1. EFFECTS OF ANGUS SIRE LINE AND
BACKGROUNDING DIET ON BEEF CATTLE
PROGENY POST WEANING PERFORMANCE
AND CARCASS VALUE
R.R. Mills1, T. DelCurto2, and C.J. Mueller3
1Extension Livestock Agent, Oregon State University Extension Service, Umatilla County, Pendleton, OR 97801
2 Director, Eastern Oregon Agricultural Research Center, Oregon State University, Union, OR 97883
3Assistant Professor, Eastern Oregon Agricultural Research Center, Oregon State University, Union, OR 97883
Abstract Materials and Methods Results
One hundred seven Angus-sired calves were Two Angus sire lines: 1) Bextor - conventional US grain The FORAGE calves were lighter (P=0.07) than their
backgrounded for 45 days on either a starch-based or based sire (CONV) or 2) Wiegroup 41/97 - New Zealand CONV counterparts at the beginning of backgrounding, but
fiber-based diet and finished in a commercial feedyard to forage based sire (FORAGE). gained adequate weight during the 45 day period to obtain
evaluate the impact of two Angus sire lines and Calves representing both sire lines (n=107; mean weight 696 similar weights prior to finishing (Table 2). The CONV
backgrounding diet on post weaning performance and lbs). calves performed better during the finishing period with a
carcass value. The two sire lines were represented by a Two 45 day backgrounding dietary treatments (formulated higher ADG (3.64 vs. 3.42 lbs/day for CONV and FORAGE
conventional grain-based developed sire typical of US for a minimum 0.75 lb ADG; NRC 1996) respectively; P<0.05) and greater final weights at harvest
production (CONV) and a forage-based developed sire CONV – Starch (barley) based diet (1312 vs. 1254 lbs. respectively for CONV and FORAGE;
typical of New Zealand production (FORAGE). During FORAGE – Fiber (soybean hulls) based diet P=0.03). The CONV calves had heavier carcass weights, a
the 45 day backgrounding period the primary dietary Finished in a common pen in a commercial feedyard. larger ribeye area, and greater marbling scores compared to
energy source was rolled barley (starch-based diet) or Carcass data obtained in a commercial abattoir (Tyson the FORAGE calves (P<0.04). The FORAGE calves had
soybean hulls (fiber-based diet). Following Fresh Meats, Pasco, WA) by trained University personnel greater backfat accumulation (P<0.005) which resulted in
backgrounding, calves were finished in a commercial (USDA 1997). higher numerical USDA yield grades (P<0.05).
feedyard in a common pen on a typical starch-based
finishing ration. Sire line had no effect on backgrounding
ADG (0.93 and 1.08 lbs/day) or final backgrounding Table 1. Backgrounding Diet Formulation and Nutrient Table 2. Feedlot Performance and Carcass
weight (749 and 732 lbs) for CONV and FOARGE Composition Characteristics
respectively, P>0.10. There were no diet type x sire line Starch Fiber CONV FORAGE SEM
interactions during the backgrounding period (P>0.10).
During the finishing period, CONV calves had higher Formulation Background initial wt., lbs. 708 684 9.11
ADG (3.64 vs. 3.42 lb/day; P=0.06) and heavier final Rolled barley, % 44.8 0.0 Background final wt., lbs. 749 732 9.21
weights at harvest (1312 vs. 1254 lbs; P=0.03). The
CONV calves had heavier carcass weights (P<0.02), Soybean hulls, % 0.0 47.0 Background ADG, lbs. 0.93 1.08 0.07
larger ribeye areas (P<0.04), and higher marbling scores Soybean meal, % 55.2 53.0 Finish final wt., lbs. 1312 1254 18.52
(P<0.001) than FORAGE calves. The FORAGE calves
had more backfat (P<0.02) and a higher numerical USDA Nutrient analysis Finish ADG, lbs. 3.64 3.42 0.08
yield grade (P<0.05) There was no backgrounding diet Dry matter, % 89.1 89.0 Carcass hot wt., lbs. 825 786 12.02
type x sire line interaction during the finishing period
(P>0.10). Our results indicate no economical advantage Crude protein, % 33.7 32.8 Fat thickness, in 0.54 0.64 0.02
for calves in conventional US starch-based feeding NDF, % 13.9 48.9 Ribeye area, in2 14.2 13.7 0.20
systems from Angus sire lines developed from forage
based systems. ADF, % 6.5 24.8 Marbling score1 509 435 12.77
NEg, Mcal/100 lbs. 65.8 61.7 USDA Yield Grade 2.90 3.13 0.08
Introduction 1 Marbling score: 400 = small, 500 = modest
Since the 1950’s US beef producers have had
abundant access to inexpensive grains, which has led to Implications
less emphasis on efficiency of forage use. As a result,
the beef breeds used in our current beef industry have The findings of our current study indicate no economical
been developed under a scenario of cheap gains and with advantage for calves in conventional US starch-based
a goal of maximizing total pounds of calf produced. feedings systems from Angus sire lines developed from
Simultaneously, New Zealand beef cattle genetics have forage based systems.
been developed under a forage-based system. Due to
recent feed commodity price volatility, some producers
have begun to re-evaluate their breeding programs and
are attempting to refocus on genetics that emphasize Literature Cited
forage utilization. But little research has been conducted
on the performance of cattle selected for efficiency of Mueller, Chad J., Tim DelCurto, and Randy R. Mills. 2011. Impact of nutrient
resources during bull development on calf crop growth through slaughter.
forage utilization in a typical US starch-based Oregon State University Oregon Beef Council Report BEEF70, pp 53-55.
backgrounding / finishing system. Our current study was
NRC. 1996. Nutrient requirements of beef cattle. Update 2000. National
designed to evaluate gain performance and carcass merit Academy Press, Washington, DC.
of terminal offspring sired by either grain-based or forage- USDA. 1997. Official United States Standards for Grades of Carcass Beef.
based genetics in a typical US production scenario. Agricultural Marketing Service, US Department of Agriculture, Washington, DC.