Progress 07/01/05 to 06/30/07
Outputs
Data were collected from the Young Sire Evaluation Program at the West Virginia University Experiment Station in Wardensville West Virginia from 2003 to 2006 using a total of 431 yearling bulls (388 Angus, 28 Polled Hereford, 8 Charolais, and 4 Red Angus bulls) from 26 different consigners. The test data utilized was collected during year 1 (2003-04), 2 (2004-05), and 3 (2005-06). Bulls were housed from mid-October until mid-March in 10 outdoor pens measuring 14.6 meters by 51.2 meters with an area of 14.6 meters by 10.7 meters being under roof. Bulls were 7 to 11 months old (born between December 1 and March 31) at the beginning of test, weaned and vaccinated according to guidelines (http://www.wvbeef.org/wbt) prior to entry, and were assigned to contemporary pens based on weight and age. In years 1 and 3, bulls were tested for 113 and 98 days, respectively. In year 2, bulls were split into two contemporary groups due to the high number of older bulls (born prior to
January 16), which were tested for 84 d and the younger bulls were tested for 115 d. All bulls were weighed every 2 weeks for the duration of their respective test to obtain an accurate growth curve for each animal. The test ration fed was primarily a hay based diet with approximately 65.7% TDN and 12.7% CP (test year 1, 2, and 3 diets contained 67% and 12%, 65% and 13%, and 65% and 13% TDN and CP, respectively). The GrowSafe 4000E System was used to determine individual feed consumption. The objectives of this study were to validate the use of residual feed intake (RFI), as compared to gain to feed ratio (G:F) as a measure of feed efficiency in purebred beef bulls, and to explore any potential relationships that may exist within other production traits including RFI. Age of dam, carcass traits, growth, production traits and individual feed intakes were recorded for 431 yearling bulls over three test years. Pearson correlations were determined between all recorded variables. Over the
3 test years, RFI was only correlated with measures of feed intake, and other feed efficiency measures. While G:F was correlated with these same traits, there were relationships with age (R2 = -0.35), weight (R2 = -0.51), total test gain (R2 = 0.59), and muscle score (R2 = -0.11). Although, selection on efficiency utilizing G:F could lead to increased weight gain, subsequently it could also select against older, heavier weight and heavier muscled animals. Relationships between common production traits were mostly low to moderate with a few exceptions. Weight per day of age accounted for a substantial portion (R2 = 0.89) of the variability in adjusted yearling weight while frame score and ribeye area accounted for 58 and 54%, respectively. As expected, backfat and percent intramuscular fat showed moderate correlations (R2 = 0.32) with one another. Furthermore, ribeye area had relatively low correlations with backfat, percent intramuscular fat and ADG (R2 = 0.24, 0.11 & 0.22,
respectively). Numerous relationships between common production traits can and do exist. Thus, care must be taken in selection of herd replacements as to not practice single-trait selection as other attributes will be affected.
Impacts
In beef production systems the weight of the animal is the single most important component in determining value. Thus, the ability to identify and propagate cattle that are efficient in converting feed into weight gain becomes an important component of a successful cow-calf unit. A one pound improvement in dry matter feed conversion of feeder calves reduces feed cost by $50 per head. Improved feed efficiency in cow-calf operations will reduce input cost and enhance profit potential for beef producers. Furthermore, the production of offspring is the driving force behind most cow/calf operations. Improved utilization of forage by beef cows, stocker cattle and steers and heifers in forage fed beef programs will provide additional economic impact and increase the number of animal units that can be produced per acre.
Publications
- No publications reported this period
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Progress 07/01/05 to 06/30/06
Outputs
An analysis of production data from two bull tests (yr1 & yr2; n = 266) was conducted examining the relationships between various production traits including residual feed intake (RFI). RFI was determined by regression analysis of actual intake on midpoint MBS and ADG. Data were analyzed by the CORR and GLM procedures of SAS utilizing data for each year both data independently and combined. Utilizing RFI as a selection tool has been previously discussed as a more independent measure of efficiency than are traditional methods (G:F, Feed:Gain). In our analysis RFI was independent of most production variables as well. There was a strong positive relationship (P < 0.05) between RFI and total test DMI, as well as F:G for yr1, yr2, and years combined. Frame score and RFI, had no relationship to one another in yr1, had a weak positive relationship (P < 0.05) in yr2, and a trend for a weak relationship with years combined. This may indicate that smaller frame bulls are more
efficient. These relationships noted were the only relationships discovered with RFI. Regardless, producers are ultimately concerned about the sale price of the bull. Sale price had the strongest relationships (P < 0.05) in yr1 with rib-eye area (REA), sale order, final BW, and % i.m. fat and adjusted yearling weight, weight per day of age (WDA), final BW and sale order in yr2 respectively. When years were combined, sale order, adjusted yearling weight, total test DMI, and WDA had the greatest impact on sale price (P < 0.05). Age of dam had a negative relationship with REA and sale price (P < 0.05) for yr1. In yr2, as the age of dam increased so did the birth weight, WDA, final BW, frame score, and total test expected DMI. When years were combined, birth weight, WDA, frame score, and total test DMI increased as the age of dam increased (P < 0.05). This data indicates that RFI can be used as a selection tool. A pilot trial of adaptation of the feed efficiency system used for bulls at
Reymann Memorial Farms - Wardensville was carried out with 37 University-owned ram lambs in late spring and summer, 2005. The trial showed a clear difference in the feed efficiency of rams, nearly 100 lbs. less feed required by the most efficient ram than by the least efficient ram over the 60-day trial. The most efficient ram would save a sheep producer about $12.00 as compared to the least efficient ram. Feed efficiency is a moderate to highly heritable trait, so given the variability among ram lambs, a great deal of genetic improvement can be made.
Impacts
In livestock production systems the weight of the animal is the single most important component in determining value. Thus, the ability to identify and propagate livestock that are efficient in converting feed into weight gain becomes an important component of a successful production unit. Improved feed efficiency in beef and sheep operations will reduce input cost and enhance profit potential for beef and sheep producers. Furthermore, the production of offspring is the driving force behind most cow/calf and lambing operations. Improved utilization of forage by will provide additional economic impact and increase the number of animal units that can be produced per acre.
Publications
- No publications reported this period
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