This newsletter is published by Texas AgriLife Extension – Animal Science. Media, feel free to use this information as needed and cite Texas A&M University Beef Cattle Browsing Newsletter, Dr. Steve Hammack.
Editor: Dr. Stephen Hammack, Professor & Extension Beef Cattle Specialist Emeritus
Feedyard data were analyzed on 443,129 head collected from January, 2004 through December, 2009. During this period, slaughter prices ranged from $0.75/cwt to $1.00/cwt, ration costs ranged from $153/T to $315/T, and the Choice-Select carcass price spread ranged from $0/cwt to $23/cwt. Since 1973, cattle feeding averaged a loss of $1.50/hd, ranging from a loss of $250/hd to a profit of $350/hd. Those figures account for interest but not risk management. Those are averages. Regardless of the month, some pens return more than others. What factors make the difference among pens?
In these data there was little correlation between purchase price and feeding performance or carcass value, presumably due to variations in marketing conditions, selling location or region, and buying and marketing methods. So, initial feeder cost was standardized using weekly-average Chicago Mercantile Exchange prices for 750 lb feeder steers, adjusted for any variation from that weight.
Pens were divided by month of close-out into three groups of equal number based on profit. Profit groups differed little for initial weight or days on feed. The high-profit group had higher ADG, total gain, slaughter and carcass weight, % Choice or Prime, and % Certified Angus Beef® or other upper 2/3 Choice Premium. The middle-profit group was intermediate on these factors and the low-profit group was lowest. The high-profit group had higher % Yield Grade 4 and 5, the low-profit group was lowest, and the middle group was intermediate.
Another analysis divided pens by month into three groups based on Quality Grade. Again, there was little difference among groups in initial weight or days on feed. In addition to higher QG resulting from the grouping, the high-QG group had higher ADG, total gain, slaughter and carcass weight, and YG 4 and 5. Calculated profit was: High QG = $35/hd, Middle QG = $24/hd, Low QG = $18/hd.
Pens were also grouped into thirds based on ADG. Higher ADG pens were also higher in feeding performance and QG but also had higher % YG 4&5. Profit was: High ADG = $45/hd, Middle ADG = $28/hd, Low ADG = $4/hd. In a grouping based on days on feed, performance and carcass traits varied little except that longer days on feed resulted in more total gain, but lower ADG, to about the same final and carcass weight. Profit varied less than $5/hd for the three DOF groups. With three groups based on carcass weight, profit was: High Wt = $40/hd, Middle Wt = $28/hd, Low Wt = $9/hd.
Other findings were:
- discounts because of Yield Grade were more than offset by premiums for Quality Grade and more pounds of carcass weight;
- gain and feed efficiency impacted profit most when ration cost was high;
- when ration cost was low, highest profit came from lightweight feeders fed to heavier final weight, but when rations were more costly the opposite occurred;
- QG impacts profit more when ration costs are lower and the Ch-Se spread is higher;
- profit increased with increasing slaughter weight until approaching 1500 lb (presumably due to decreased feed efficiency and higher % YG 4&5 and discounts for heavy carcasses);
- profit increased with higher ADG up to 4.3 lb/day while higher ADG produced more carcasses discounted for heavy weight;
- while higher QG tended to result in higher profit, about 30% of pens grading 90% Choice and higher were in the low-profit group;
- ADG and QG were positively related up to about 75% Choice or higher, above which point ADG tended to decline;
- the optimum end-point for feeding is probably at heavier weights to higher fatness than is typical.
(Professional Cattle Consultants, Weatherford, Ok: www.pcc-online.com)
GENETICS OF SUSTAINED REPRODUCTIVE SUCCESS
Records from the American Hereford Association database were used to evaluate sustained reproductive success, defined as a female maintaining a calving interval of 425 days or less. The dataset included 36,866 females and 3,323 sires. Heritability of sustained reproductive success was 0.05. (J. Animal Sci. 89:1712; USDA-ARS Ft. Keogh Res. Lab – Miles City, MT)
NOTE: This work reinforces many other studies showing that genetic variation for most reproductive traits is low, so most of the variation in reproduction is due to non-genetic factors such as nutrition, disease, etc. It should not be surprising that genetic variation is relatively low for reproduction in domesticated livestock. Over time, both natural and human-directed selection tends to eliminate from a population those individuals that are low in reproductive expression. So, a high percentage of individuals are probably inherently fertile. Whether or not that inherent fertility is expressed often depends largely on environmental influences which can vary considerably, from one location to another and from one year to another in the same location.
COMPARISON OF TWO TREATMENTS FOR FIXED-TIME AI
Crossbred beef cows ranging from 3 to 10 years of age and 26 to 91 days postpartum were synchronized in the fall (n = 661 cows) or spring (n = 579 cows). Treatments were
- Co-Synch: injection of gonadotrophin-releasing hormone (GnRH) followed by injection of prostaglandin (PGF2α) 7 days later;
- Co-Synch + CIDR : same as above plus a CIDR (progesterone-releasing device) inserted between the two injections listed above.
At 60 hours after PGF2α administration, all cows were treated with GnRH and artificially inseminated, regardless of estrus, and placed with bulls 10 days after AI. Progesterone was analyzed in blood samples collected 2 weeks before initial GnRH injection, at initial GnRH injection, and at PGF2α injection. Estrous behavior was monitored by heat detectors and pregnancy was determined by ultrasound 72-77 days after AI.
At first GnRH injection, progesterone did not differ (P<0.10) but was higher (P<0.01) in Co-Synch + CIDR at PGF2α injection. At 60 hours after PGF2α, Co-Synch + CIDR cows had 67% in estrus vs. 58% for Co-Synch (P<0.01) and also greater (P<0.01) percent pregnant to AI (55% vs. 44%). When progesterone levels at PGF2α injection were low, Co-Synch + CIDR had higher (P<0.01) pregnancy rate (65% vs. 31%); there was no difference (P<0.10) between treatments when progesterone was high. Regardless of treatment, all cows expressing estrus within 60 hours before AI had higher pregnancy rates. The authors concluded that the addition of CIDR increased progesterone level, percent detected in estrus, and pregnancy rate, primarily in cows with low or decreasing levels of endogenous progesterone. (J. Animal Sci. 89:3060; U. S. Meat Anim. Res. Ctr.)
HAIR COAT SHEDDING IN ANGUS COWS
Hair coat has been shown to influence heat tolerance. A dense, dark coat reduces evaporative cooling under conditions of high temperature and humidity. A study was designed to evaluate: 1) a method of assessing shedding; 2) variation in shedding; 3) effects on weaning weight and Body Condition Score (BCS). Angus cows (n=532) were evaluated over three years at four locations in North Carolina and Mississippi. Cows were 2- to 13-years old, calving was in the fall or spring, and all cows weaned a calf. Cows were evaluated approximately every 30 days in late March through late July. Scoring was: 1 = slick coat; 2 = more than halfway shed; 3 = halfway shed; 4 = started shedding; 5 = thick coat. Five groupings were made based on the month when winter coat shedding started (month of first shedding, MFS), defined as a score of 3 or less. An adapted score (AS) was assigned with cows having MFS in March, April, or May considered subtropically adapted and those in June or July were considered unadapted.
Cows with spring AS weaned heavier (P< 0.05) calves than summer AS by 24 lb. There was no difference within AS groups. Cow BCS did not significantly differ among MFS or AS. Heritability of AS was 0.35. The authors concluded that “cows with scores of 4 or 5 should be culled”. NOTE: An alternative could be the use of types and breeds in which all individuals shed before summer. (Proceedings of 2011 Beef Improvement Federation Annual Meeting, p. 69; North Carolina St. Univ., Mississippi St. Univ.)
DISTILLERS GRAINS FOR GROWING CATTLE
Various coproducts of corn processing are being widely used in finishing cattle, at least where they are economically available. A study was designed to evaluate dried distillers grains with solubles (DDGS) for growing cattle. A group of 144 Angus-cross steers initially averaging 554 lb was divided into three groups based on initial weight (Small, Medium, Large) and assigned to one of four treatments for 98 days:
- 65% DDGS fed to gain 2lb/day (DLo)
- 65% DDGS fed to gain 3 lb/day (DHi)
- 65% corn fed to gain 2 lb/day (CLo)
- 65% corn fed to gain 2 lb/day (CHi)
After the growing period, all steers were put on a full finishing ration and fed until the Large group averaged 1200 lb, the Medium group averaged 1150 lb, and the Small group averaged 1100 lb.
As had been shown by previous research over the years, compensatory gain resulted in the Lo groups having higher ADG during finishing. Source of energy during growing did not affect finishing ADG. After finishing, Lo steers had less fat cover, numerically lower Yield Grades, and larger ribeyes. There were some interactions regarding marbling; CLo had the highest marbling and DLo the lowest while CHi had lower marbling than CLo but DHi had higher marbling than DLo. The authors concluded that DDGS can be effectively used for growing but interactions for marbling involving energy source and rate of growing should be considered. (J. Animal Sci. 89:2273; Ohio St. Univ., Univ. of Wisconsin)
GENOMICS TO PREDICT RESIDUAL FEED INTAKE (RFI), ADG, AND DRY MATTER INTAKE (DMI)
Individual feed consumption and DNA collected over 5 years from 721 crossbred beef steers were analyzed. Steers were by three sire breeds out of crossbred cows. Accuracy of predicting RFI was determined using a 50,000 (50k) single nucleotide polymorphism (SNP) panel and a panel containing the 200 SNPs found to be most highly related to RFI.
As has been shown in other studies, RFI and ADG were essentially independent of each other. However, correlations (both genetic and phenotypic) between DMI and ADG and between DMI and RFI ranged from 0.51 to 0.64. So, cattle that ate more tended to gain faster but were less efficient (higher numerical RFI). For the 200 SNP panel, accuracy of prediction for RFI, ADG, and DMI ranged from 0.22 to 0.48, with RFI being highest. For the 50k panel, accuracy ranged from 0.11 to 0.25, with DMI being highest. The authors concluded, “The results obtained from this study demonstrate that the utility of genetic markers for genomic prediction of RFI in beef cattle may be suboptimal.” NOTE: Utility of genomic prediction of RFI has been found to be more favorable in studies confined to a single breed. (J. Animal Sci. 89:3353; Univ. of Alberta, Alberta Ag. and Rural Devel. Centre at Lacombe, Colorado St. Univ.)
BEEF COWS: 2008 VS. 1920
Various practices and characteristics of beef cow herds were surveyed in 2007-08 by the USDA National Animal Health Monitoring System. The survey reached operations in the 24 states comprising 80% of US beef cow operations with 88% of the nation’s cows. A comparison was made between cow numbers in 2008 and 1920. In 2008 there were 32.4 million beef cows, which comprised 78% of all cows in the country. In 1920 there were 12.5 million beef cows but these made up only 37% of all cows. This means that the total number of cows has increased 23% but beef cow numbers have increased 259%. My assessment of this is that many farms in 1920 had a milk cow or two, and maybe a few beef cows, but maintaining large numbers of cows strictly for beef production was not as prevalent in 1920. (http://www.aphis.usda.gov/animal_health/nahms/beefcowcalf/index.shtml#beef0708)