Location: Nutrition, Growth and Physiology2014 Annual Report
Objective 1: Determine the nutrient value and environmental consequences of novel feed products. Component 1: Problem Statement 1A Objective 2: Improve determination of dynamic changes in nutrient requirements as the animal’s physiological status changes to allow for timed nutrient delivery. Component 1: Problem Statement 1A Objective 3: Determine the role of malnutrition during critical periods in developmental programming and epigenetic effects that alter lifetime production potential and product quality. Component 1: Problem Statement 1A Objective 4: Determine metabolic and physiological mechanisms responsible for variation in feed efficiency that is under genetic control. Component 1: Problem Statement 1A Objective 5: Determine age, gender, genetic, and environmental factors that account for variation in feeding activity and growth of swine Component 1: Problem Statement 1C Objective 6: Characterize the response of cattle to changes in environmental temperature with respect to various management strategies and animal risk factors. Component 1: Problem Statement 1C Obective 7: Determine the relationships between ruminal microbial communities, animal genotype, and/or methane production with feed/nutrient use efficiency and/or lactation performance in response to varying nutritional regimens in beef or dairy cattle. Component 1: Problem Statement 1A Component 2: Problem Statement 2B; Problem Statement 2D
Feed costs represent the single largest input in both beef and swine production; however, less than 20% of the feed energy is converted to edible product. Improving the efficiency that feed is converted to animal products has the potential to improve the economic efficiency of animal production while improving the sustainability of animal agriculture. To maximize feed efficiency the correct profile of nutrients are matched to meet an animal’s needs for its current biological status (growth, pregnancy, lactation, previous nutrient history, and disease). In order to provide the correct profile of nutrients, the nutrient composition of feeds and the dynamic nutrient requirements of the animal must both be identified and then synchronized. There is genetic variation amongst animals in their ability to utilize feed. Multiple genes are associated with the regulation of feed intake, and the utilization of ingested nutrients. Differential expression of these genes results in variation of feed efficiency amongst animals within populations, and these genetic differences potentially change the nutrient requirements of the animal. Nutrient status during critical periods of development (fetal and peripuberal) can permanently modify the expression of genes changing the lifetime feed efficiency of an animal. Identifying the role of nutrition in regulating gene expression is needed to develop nutrition management strategies across generations of animals in a production system.
Two replicates of 600 pigs each were weaned from the sow at 26 d of age, blocked by litter and gender, and then randomly assigned to one of 24 pens in either a nursery room that had been fully disinfected or a nursery room left unclean after the previous group of pigs. Within a room, pigs were randomly assigned to control diets, control diets + antibiotics, or control diets + lysozyme. Rectal swab samples were collected on d 0 and 28 of treatment, enriched and cultured for Campylobacter spp., and shigatoxigenic Escherichia coli, and analyzed for enterohemorrhagic E. coli virulence genes. Room hygiene and diet had little effect on shigatoxigenic or enterohemorrhagic E. coli, but percentage of samples cultured positive for Campylobacter spp. was lowest for the lysozyme diet compared to control and control + antibiotic diets. Thus, lysozyme in the diet can reduce fecal shedding of Campylobacter spp. from nursery swine (Objective 1). To determine differences in feeding behavior in the finishing phase of production between barrows and gilts, 240 pigs (mix of barrows and gilts), ear-tagged with a half-duplex, low frequency, passive EID tags were distributed in 1 of 6 pens each equipped with the feed behavior monitoring system (Objective 5). Feeding behavior of three different sire-lines (Yorkshire, Landrace, and Duroc) at different temperatures was determined on 234 finishing pigs. Feeding behavior was measured using half-duplex, low frequency, passive electronic identification (EID) ear tags in six pens equipped with feed behavior monitoring system. Temperature and humidity were monitored at two points within the barn (Objective 5). Heat tolerance was determined in 180 pigs from three different sire lines as nursery, growing, and finishing pigs. Heat tolerance was assessed using thermal images captured at different temperatures (Objective 5). Four-hundred and thirty-eight beef steers were used to determine the effects of feeding dry-rolled corn-based diets with and without wet distillers grains with solubles and zilpaterol hydrochloride on animal performance, carcass characteristics, and heat stress. Animal performance data were collected, respiration rate and panting score were determined as indicators of heat stress, and steers were slaughtered and carcass quality was determined (Objective 1). Blood metabolites and whole-animal oxygen consumptions were determined on eight steers receiving zilpaterol hydrochloride and eight control steers. Blood samples were collected at day -1, 2, 6, 13, 20, and 27, and oxygen consumption was determined the following day (Objective 1). Eight steers were placed on one of four glycerin inclusion levels to determine the optimum glycerin level in a dry-rolled corn-based diet. Energy metabolism and nutrient balance data were collected over an 84-day period (Objective 4). Blood samples were collected from 245 individually fed finishing beef steers and heifers. Samples were analyzed for the gut peptide ghrelin (active and total) along with selected metabolites to determine the association of ghrelin with feed intake and efficiency (Objective 4). DNA was isolated from 245 steers and heifers to be used in a genotyping assay to determine the association of single nucleotide polymorphisms in genes related to ghrelin activity with circulating levels and forms of ghrelin and its association with feed intake (Objective 4). Blood samples were collected at three time points during a feed intake and growth measurement period from 255 individually fed finishing beef steers and heifers. A portion of the samples were stored for later metabolomic analysis. Samples were also analyzed for leptin to determine the association of leptin with feed intake, growth, and feed efficiency (Objective 4). Blood and fecal samples were collected for 255 individually fed steers and heifers at the end of a feed intake and growth measurement period. Fecal samples are being analyzed for a glucocorticoid metabolite and blood samples were analyzed for blood cell counts, cortisol, and selected metabolites to determine the association of inflammation and immune function with feed efficiency in finishing beef cattle (Objective 4). Serum leptin was analyzed on 766 steers from the Germplasm Evaluation population to determine the association of leptin with feed intake and other production measure in finishing cattle (Objective 4). The DNA was isolated from 1021 steers and heifers to be used in a genotyping assay to determine the association of single nucleotide polymorphisms (SNPs) in leptin and the leptin receptor and determine the effect of the SNPs on leptin association with feed efficiency and the association of the SNPs with leptin concentrations (Objective 4). The ribonucleic acid (RNA) from the duodenum and rumen tissue of 16 steers was evaluated for differences in the transcriptome among animals with extreme feed efficiency phenotypes. The SNPs identified in the genes that were differentially expressed in the rumen tissue were used to genotype over 1,100 steers to determine whether these SNP segregate with specific phenotypes (Objective 4). The rumen papillae morphology from 64 steers with extreme feed efficiency phenotypes was evaluated (Objective 4). Rumen microbiome was determined on 32 steers that varied in feed intake and body weight gain (Objective 4). The transcript abundance of seven genes within a region on chromosome 15 associated with gain in beef cattle was examined in a library of tissues from 46 steers with extreme gain or extreme gain and feed intake phenotypes (Objective 4). Production records were recorded on 413 cows that had been developed under two different regimens as heifers. Thirty heifers were developed on two diets. Ovaries were collected at three time points and histology and gene expression analyses were performed (Objective 3). Production records were collected on 279 cows that had experienced different fetal nutrition (Objective 3). A heat stress prediction model was developed to summarize weather factors into a single index value. A feedlot cattle heat stress website utilizes both the prediction model developed at USMARC and NOAA-NWS digital forecast maps. The website’s primary feature is a seven-day graphical forecast of cattle heat stress. Based on feedback from producers, the forecast application is being developed. An evaluation of three different types of body temperature monitoring systems was completed in feedlot heifers. Thirty heifers were instrumented with rumen bolus, vaginal probes, and ear-canal temperatures. Data was collected over 2 two-week periods (Objective 6).
1. Methane produced by cattle can increase when the efficiency of feed conversion to body weight gain increases. Methane gas released by cattle is a product of fermentation in the digestive tract. Released methane represents both a lost opportunity to capture dietary energy and a source of greenhouse gas. ARS researchers at Clay Center, Nebraska, conducted two experiments to determine the relationship between the efficiency of feed utilization for body weight gain, and the amount of methane produced. On a high-forage diet, methane emissions increased with increased feed efficiency. There was not a relationship between methane production and feed efficiency on a high-grain diet. Their findings suggest that selecting only for reduced methane may have a negative impact on conversion of feed to body tissues.
2. Feeding a by-product of ethanol production to cattle reduces the amount of additional roughage required in diets. Roughage in feedlot diets promotes good digestion; however, it is a costly portion of the diet. ARS researchers at Clay Center, Nebraska, determined that nutrient retention in feedlot cattle can be improved by reducing the amount of alfalfa hay used in finishing diets containing at least 25% wet distillers grains with solubles. These studies demonstrate that the cost of feed can be reduced by decreasing roughage concentration in diets when distiller grains are fed.
3. There is increased expression of genes in a region of the genome previously identified to be associated with feed intake and body weight gain in cattle. Feed is the single largest input cost associated with beef production. Cattle differ in their ability to convert feed to meat and those differences are heritable. ARS researchers at Clay Center, Nebraska, determined that expression of markers in adipose tissue of heifers and cows and their expression in muscle of steers was correlated with variation in feed intake. The expression of this gene in the muscle of cows was correlated with variation in average daily gain. These data support earlier genetic associations with feed intake and body weight gain within this region and represent the potential for biological activity of these genes in the muscle and adipose tissues of beef cattle; however, they also suggest that sex, age and/or nutrition-specific interactions may affect their expression in these tissues.
4. Crude glycerin a byproduct of biodiesel production can be used as a feed resource for cattle. The cost of traditional feed resources has fluctuated with drought conditions, and the use of corn for biofuels. ARS researchers at Clay Center, Nebraska, and Bushland, Texas, found that body weight gain increased in steers eating diets that substitute less than 7.5% of the steam-flaked corn with glycerin; however, when glycerin was included at greater than 7.5% of the diet, body weight gain decreased. Feed efficiency decreased with increased substitution of glycerin for corn. Adding glycerin to cattle diets is more effective when it replaces alfalfa hay rather than corn. These studies suggest the moderate inclusion of glycerin in beef cattle diets can be used as a strategy to reduce diet cost.
Hales, K.E., Brown-Brandl, T.M., Freetly, H.C. 2014. Effects of decreased dietary roughage concentration on energy metabolism and nutrient balance in finishing beef cattle. Journal of Animal Science. 92(1):264-271.
Camacho, L.E., Lemley, C.O., Prezotto, L.D., Bauer, M.L., Freetly, H.C., Swanson, K.C., Vonnahme, K.A. 2014. Effects of maternal nutrient restriction followed by realimentation during midgestation on uterine blood flow in beef cows. Theriogenology. 81(9):1248-1256.
Lindholm-Perry, A.K., Kuehn, L.A., Oliver, W.T., Sexten, A.K., Miles, J.R., Rempel, L.A., Cushman, R.A., Freetly, H.C. 2013. Adipose and muscle tissue gene expression of two genes (NCAPG and LCORL) located in a chromosomal region associated with cattle feed intake and gain. PLoS One. 8(11):e80882.
Lindholm-Perry, A.K., Kuehn, L.A., Oliver, W.T., Kern, R.J., Cushman, R.A., Miles, J.R., McNeel, A.K., Freetly, H.C. 2014. DNA polymorphisms and transcript abundance of PRKAG2 and phosphorylated AMP-activated protein kinase in the rumen are associated with gain and feed intake in beef steers. Animal Genetics. 45(4):461-472.
Hales, K.E., Bondurant, R.G., Luebbe, M.K., Cole, N.A., MacDonald, J.C. 2013. Effects of crude glycerin in steam-flaked corn-based diets fed to growing feedlot cattle. Journal of Animal Science. 91(8):3875-3880.
Hales, K.E., Kraich, K.J., Bondurant, R.G., Meyer, B.E., Luebbe, M.K., Brown, M.S., Cole, N.A., MacDonald, J.C. 2013. Effects of glycerin on receiving performance and health status of beef steers and nutrient digestibility and rumen fermentation characteristics of growing steers. Journal of Animal Science. 91(9):4277-4289.
Davis, M.P., Freetly, H.C., Kuehn, L.A., Wells, J. 2014. Influence of dry matter intake, dry matter digestibility, and feeding behavior on body weight gain of beef steers. Journal of Animal Science. 92(7):3018-3025.
Kim, M.S., Kim, J., Kuehn, L.A., Bono, J.L., Berry, E.D., Kalchayanand, N., Freetly, H.C., Benson, A.K., Wells, J. 2014. Investigation of bacterial diversity in the feces of cattle fed different diets. Journal of Animal Science. 92:683-694.
Freetly, H.C., Brown-Brandl, T.M. 2013. Enteric methane production from beef cattle that vary in feed efficiency. Journal of Animal Science. 91(10):4826-4831.