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Title:Determining the added value of coproducts based adaptation diets and the heritability of variation in feed intake in Red Angus cattle
Author(s):Fritz, Adam P.
Advisor(s):McCann, Joshua C.
Contributor(s):Shike, Daniel W.; Parrett, Douglas F.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
feed intake
Abstract:The main goal of the feedlot industry is to maximize growth in cattle while minimizing costs in all phases of the finishing period. Traditionally, this is done by feeding diets high in grain to maximize energy intake. However, cattle coming to the feedlot are typically consuming diets high in forage and need time to adapt to a high grain diet. In order to achieve this, diets containing decreasing amounts of forage with increasing amounts of grain are fed in a series of steps. This strategy allows time for the rumen epithelium and microbiome to adjust to high grain diets. Although grains are typically fed as the main energy source in a diet, grain coproducts also contain a great amount of easily digested fiber, which can decrease the risk for metabolic disorders while maintaining energy levels in a diet. Previous findings have suggested that feeding coproducts in adaptation diets could be advantageous by not only increasing performance during adaptation, but also into the finishing phase. Another goal of the feedlot industry is to get cattle eating as consistently as possible to decrease the possibility of metabolic disorders. Fluctuations in daily feed intake, especially of a finishing diet due to its high grain content, are known to increase the risk of acidosis. Acidosis can lead to a multitude of other issue, such as liver abscesses and laminitis, which decrease profitability of a feedlot. Heritability estimates give producers the ability to determine how impactful their selections for a given trait are based on genetics. Considerable research has evaluated the heritability of feed intake and the efficiency of cattle based off of residual feed intake and other measures of efficiency, but none have determined the heritability of fluctuations in daily dry matter intake. Selecting for cattle that consume feed more consistently could reduce the number of metabolic issues in feedlots and increase profitability. Due to previous research by Crawford (2018) at the University of Illinois, an experiment was conducted to determine the effect of replacing forage with coproducts in adaptation diets on growth performance and the rumen microbiome after steers are consuming a common finishing diet. Simmental × Angus and Angus steers (N = 135; 256.3 ± 27.2 kg) were blocked by initial BW and allotted into 9 pens. Steers were fed a common receiving diet for the initial 12 days after weaning. Pens were then assigned to 1 of 3 dietary treatments for the 35 d adaptation period: a forage-based diet (FO; alfalfa and grass hay) with decreasing inclusion of forage and increasing dry-rolled corn inclusion fed with slick bunk management, a coproduct-based diet (CO; soybean hulls and modified wet distillers grains with solubles) with decreasing inclusion of coproducts and increasing dry-rolled corn inclusion fed with slick bunk management, and the coproduct-based diet pair-fed (CO-P) to isoenergetic levels of FO. After the adaptation period, steers were fed a common finishing diet for the remainder of the trial (155 d). During the adaptation period, DMI was greatest for steers fed CO (P = 0.02). On d 40, there were no differences (P ≥ 0.37) in BW or ADG between treatments. A treatment × sampling day interaction (P = 0.02) was observed for in vitro dry matter disappearance. On d 35, in vitro dry matter disappearance was greater (P < 0.01) in steers fed CO compared with CO-P (58% vs. 53%), but no differences were present on d 63. At d 63, BW was not affected (P = 0.71) by treatment. At the end of the finishing period, there were no differences (P ≥ 0.26) in BW, overall ADG, gain:feed, or carcass traits at slaughter. The high inclusion of coproducts in adaptation diets did not affect the subsequent growth performance of steers consuming a common finishing diet. In vitro and rumen microbiome results suggest all treatments were adapted for the finishing diet at the conclusion of the 35 d adaptation period. Unpublished data by McCann at the University of Illinois has indicated that daily feeding fluctuations greater than 30% are a marker for increased risk for acidosis. Therefore, a second study was done to determine the heritability of variation in daily intake in Red Angus cattle. Data from three locations was compiled and pooled together to evaluate the genetic variation of average DMI, standard deviation of DMI, coefficient of DMI, and percentage of days with fluctuations of DMI greater than 30%. The dataset contained 209 sires with an average of 12.0 ± 31 progeny per sire with the top ten sires representing 1225 progeny. Heritabilities were as follows: average DMI, 0.57, standard deviation of DMI, 0.74, coefficient of DMI, 0.74, and percentage of days with fluctuations of DMI greater than 30%, 0.12.
Issue Date:2019-04-25
Rights Information:Copyright 2019 Adam Fritz
Date Available in IDEALS:2019-08-23
Date Deposited:2019-05

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