Author: Michael Patrick Davis Publisher: ISBN: Category : Beef cattle Languages : en Pages : 90
Book Description
Residual feed intake (RFI) is the difference between measured feed intake and predicted feed intake of an animal. Intake prediction is computed from a regression of intake on gain and metabolic body weight. Residual feed intake is used as a measure of metabolic efficiency. As RFI increases, feed intake (FI) and feed conversion ratio (FCR) increase with no change in postweaning growth and body weight in steers. Identification and selection for lower RFI cattle would improve herd feed efficiency without influencing growth. Steer residual feed intake measured in the growing phase, is related to residual feed intake during the finishing phase. Animals with low residual feed intake in the growing phase had lower residual feed intake and improved feed efficiency in the finishing phase. Serum concentrations of glucose and mitochondrial function are related to metabolic efficiency and may differ between residual feed intake phenotypes. Serum concentrations of glucose at weaning were greater (P [lesser than] 0.05) in low (efficient) compared to high (inefficient) RFI steers. Mitochondrial complex protein concentrations I:II and I:III ratios were greater (P [lesser than] 0.05) in low extreme versus high extreme RFI steers. Diets varied in rumen undegradable protein content were used to determine impact of intestinal amino acid supply on growth performance. Increasing rumen bypass amino acids in no roughage diets during the growing phase tended (P [lesser than] 0.15) to influence ADG and FCR in the growing phase such that as rumen bypass amino acid level increased growth and feed efficiency improved in the growing phase. Steers fed post ruminal absorbable amino acid levels below that required for growth in growing phase tended (P [lesser than] 0.15) to have improved feed efficiency in the finishing phase. Also, during the growing phase as bypass amino acids increased subcutaneous and intramuscular fat deposition decreased in steers during the finishing phase. Feeding a level of bypass amino acids below optimum for growth to steers during the growing phase decreased (P [lesser than] 0.05) longissimus dorsi muscle area in steers during the finishing phase.
Author: Mariana Medeiros Masiero Publisher: ISBN: Category : Languages : en Pages : 139
Book Description
Residual feed intake (RFI), used as a metabolic efficiency measurement, is BW and growth rate independent and also is a moderately heritable trait. Previous research reported RFI was correlated to feed activity and behavior, ruminal fermentation nutrient digestion, body composition, blood hormones and metabolites as well as mitochondria function. Since mitochondria are responsible for producing 90% of the energy for the cell, some of the variations in growth performance and phenotypic expression of feed efficiency might be due to differences or inefficiencies in mitochondria function. Three studies were conducted to understand how AA requirement and mitochondria function influence different RFI phenotypes. The first study had 3 diets with increasing RUP (LOW, MID and HIGH) fed to continuous culture fermenters to characterize RUP supplementation using forage-based diet. We observed RUP supplementation in forage-based diets increased RUP flow from the rumen without influencing microbial fermentation. Reduced RUP for HIGH compared to MID may be due to microbial adaptation to greater RUP levels. The second study evaluated the effects of postruminal AA supply during the GP on growth performance, carcass measurements, RFI, and blood metabolites using roughage-based diet. We reported no interaction between level of bypass AA during growing phase and RFI, leading to main effects examination. Calves consuming diets with postruminal AA supplied above requirements may respond with greater gain rate, however improved growth was not sustained throughout the feeding period. As RFI decreased, steers consumed less feed and were more efficient with no change in BW during all periods. Steers classified as efficient during growing phase were not necessary in the same category during finishing phase. The last study conducted determined if mitochondria complex I, complex III and subunits (from complex I) differed among RFI phenotypes and if mitochondria measurements could account for additional differences in DMI. Examination of lymphocyte mitochondria proteins (complex I, complex I subunits and complex III) found a relationship between mitochondria band I, band VI and RFI. Mitochondrial measurements increased coefficient of determination for intake prediction. These results led to the conclusion that mitochondrial function is in part responsible for animals metabolic efficiency differences.
Author: Rodney A. Hill Publisher: John Wiley & Sons ISBN: 1118388240 Category : Science Languages : en Pages : 328
Book Description
Feed Efficiency in the Beef Industry provides a thorough and concise overview of feed efficiency in beef cattle. It frames the great importance of feed efficiency to the industry and details the latest findings of the many scientific disciplines that intersect and aim to improve efficient and sustainable production of nutritious beef. The vast majority of production costs are directly tied to feed. With increased demand for grains to feed a rapidly increasing world population and to supply a new demand for alternative fuels, feed costs continue to increase. In recent years, the negative environmental impacts of inefficient feeding have also been realized; as such feed efficiency is an important factor in both economic viability and environmental sustainability of cattle production. Feed Efficiency in the Beef Industry covers a broad range of topics ranging from economic evaluation of feed efficiency to the physiological and genetic bases of efficient conversion of feed to high quality beef. Chapters also look at how a fuller understanding of feed efficiency is leading to new selective breeding efforts to develop more efficient cattle. With wide-ranging coverage from leading international researchers, Feed Efficiency will be a valuable resource for producers who wish to understand the complexities, challenges, and opportunities to reduce their cost of production, for students studying the topic and for researchers and professionals working in the beef industry.
Author: Colin G. Scanes Publisher: CRC Press ISBN: 1351648136 Category : Nature Languages : en Pages : 509
Book Description
There is increasing interest in the biology of domestic animals ranging from genomics, transcriptomics, metabolomics, nutritional physiology, and systems biology. This book touches on all of these, with a particular focus on topics such as domestic animals as comparative models to humans, molecular regulation of growth, metabolic efficiency, reproduction, and the impact of stress on growth and development. The book concludes with a discussion on the current and future directions for researchers.
Author: Marcelo Hentz Ramos Publisher: ISBN: Category : Electronic Dissertations Languages : en Pages : 67
Book Description
Residual feed intake (RFI) is a calculated using DMI as dependent variable and metabolic body weight (BW 0.75) and ADG as independent variable. Mitochondria complex I (mitochondrial NADH:ubiquinone oxidoreductase) is one of the least understood membrane bound protein complexes. Insulin resistance has been reported in calves, dairy cows, horses and swine. For all four mitochondria experiments, there was a significant difference (P 0.05) between RFI and DMI but no difference (P 0.05) was reported for ADG and MMBW. For experiments one, two and three, CI was greater (P 0.05) for -RFI compared to other treatments. The correlation between CI and RFI was -0.37 (P = 0.02), -0.48 (P = 0.034), and -0.84 (P = 0.015) for experiment one, two and three, respectively. For experiment 4, animals with -RFI had a trend for greater concentration (P = 0.07) of Band I (protein S1) than +RFI. Correlation between RFI and Band I was -0.72 (P = 0.04). A regression was developed using Band I and RFI with RFI = 6.1715 -0.00015 Band I, R2 = 0.85, RMSE = 0.62. No significant difference (P 0.05) was reported in any variable measured during both the glucose and epinephrine tolerance test. We concluded that mitochondrial function was at least in part responsible for differences among animals in metabolic efficiency. In addition, insulin resistance is not responsible for RFI classification in feedlot animals.
Author: Wimberley K. Krueger Publisher: ISBN: Category : Languages : en Pages :
Book Description
Objectives of this study were 1) to characterize the relationship between beef cattle efficiency, namely residual feed intake (RFI), and digestive, microbial, and fermentation parameters in growing beef calves and 2) to examine the effects of added dietary hydrolysable or condensed tannin on animal performance and efficiency, fermentation and carcass and non-carcass traits. To accomplish the first objective, multiple RFI studies were conducted and in all studies RFI was calculated as the difference between actual and expected dry matter intake (DMI) based on average gaily gain (ADG) and body weight0.75(BW). A total of 187 head selected out of a population of 600 head of growing beef calves were evaluated for diet and nutrient digestibility, ruminal and fecal volatile fatty acids (VFA) concentrations and methane producing activity (MPA). Low RFI calves consumed less DMI and had lower feed conversion ratios (FCR) as compared to high RFI calves. Low RFI calves also had higher diet and nutrient digestibilities compared to high RFI calves. Residual feed intake was negatively correlated with diet and nutrient digestibilities such that more efficient animals had higher digestibilities. Low RFI calves tended to have lower ruminal propionate and higher acetate:propionate ratios when fed a high-forage diet. Calves with divergent RFI did not have different gross microbial populations as evidenced by the Firmicute:Bacteriodetes ratio, but low RFI calves tended to have higher fecal Prevotella spp. and lower fecal Spirochaetes and ruminal Cyanobacteria. The importance of these subtle shifts in microbial ecology is not evident at this time and more research is needed to fully elucidate the interaction of host and microbes to fully grasp the importance of minor microbial deviations. No differences in 3 h MPA were detected in low vs. high RFI calves but low RFI calves had higher fecal MPA when sampled at 24 h; however, calculated methane emissions were lower for low RFI calves. Tannin supplementation had no effect on animal performance and efficiency, ruminal fermentation VFA concentrations, MPA, or ammonia concentrations in finishing beef steers. There was also no detrimental effect of tannins on carcass traits; however, hydrolysable tannin supplementation resulted in increased empty rumen mass. Results from these studies indicate that diet and nutrient digestibility are affected by RFI such that more efficient calves had higher DMD, microbial ecology is responsive to RFI such that minor microbial shifts were observed, and tannin supplementation, at the current inclusion rate, had no effect on animal and carcass performance.
Author: Phillip Allan Lancaster Publisher: ISBN: Category : Languages : en Pages :
Book Description
Objectives of this study were to characterize residual feed intake (RFI) in growing calves and to examine relationships with growth, carcass composition, physiological indicators, energy metabolism and reproduction. To accomplish these objectives, multiple experiments were conducted. In all experiments, RFI was calculated as the difference between actual DMI and expected DMI from linear regression of DMI on mid-test metabolic BW and ADG. To examine the relationships between RFI and rate and composition of growth, and reproduction an experiment was conducted with postweaning Brangus heifers (N = 348). Measures of carcass composition (longissimus muscle area, LMA; and 12th rib fat thickness, BF) were obtained by ultrasound at the start and end of each experiment. To determine if serum IGF-I concentration is associated with RFI, two experiments were conducted with Angus bulls and heifers (N = 95) divergently selected for serum IGF-I concentration. To evaluate relationships with energy metabolism, calves with low and high RFI were selected for determination of heart rate as an indicator trait for energy expenditure (4 experiments) and liver mitochondrial function (3 experiments). Residual feed intake was not correlated with ADG, but was positively correlated with gain in BF such that the more efficient calves were leaner. Calves from the low IGF-I selection line had lower RFI suggesting that RFI and IGF-I are related and that IGF-I could be used as an indicator trait to aid in selection for improved RFI in Angus cattle. Calves with low RFI had lower energy expenditure and greater mitochondrial acceptor control ratios than calves with high RFI suggesting improved regulation of energy metabolism. A similar percentage of heifers with low RFI attained puberty as those with high RFI by the end of the experiment. Results from this study indicate that producers can utilize RFI to select for improved feed efficiency with minimal impact on growth, carcass composition and reproduction.
Author: Rodney A. Hill Publisher: John Wiley & Sons ISBN: 0470959525 Category : Science Languages : en Pages : 328
Book Description
Feed Efficiency in the Beef Industry provides a thorough and concise overview of feed efficiency in beef cattle. It frames the great importance of feed efficiency to the industry and details the latest findings of the many scientific disciplines that intersect and aim to improve efficient and sustainable production of nutritious beef. The vast majority of production costs are directly tied to feed. With increased demand for grains to feed a rapidly increasing world population and to supply a new demand for alternative fuels, feed costs continue to increase. In recent years, the negative environmental impacts of inefficient feeding have also been realized; as such feed efficiency is an important factor in both economic viability and environmental sustainability of cattle production. Feed Efficiency in the Beef Industry covers a broad range of topics ranging from economic evaluation of feed efficiency to the physiological and genetic bases of efficient conversion of feed to high quality beef. Chapters also look at how a fuller understanding of feed efficiency is leading to new selective breeding efforts to develop more efficient cattle. With wide-ranging coverage from leading international researchers, Feed Efficiency will be a valuable resource for producers who wish to understand the complexities, challenges, and opportunities to reduce their cost of production, for students studying the topic and for researchers and professionals working in the beef industry.
Author: Brook Bradbury Publisher: ISBN: Category : Languages : en Pages :
Book Description
Feed efficiency and metabolism affect profitability of the various components of the beef industry by modulating distribution and use of nutrients within cattle. Separate studies were conducted to determine the 1) repeatability of feed efficiency measurements over time as beef heifers mature into cows, and 2) whether the production and regulation of glucose in heifers is affected by temperament. The influence of temperament on glucoregulatory hormones was studied in Angus crossbred heifers and Brahman heifers whose temperament was determined at weaning. The 6 most calm and 6 most temperamental heifers of each breed were fitted with jugular cannulas. Blood was collected at cannulation and then via the cannula during a 90-min rest period. Following 90 min, dextrose was infused (0.5 mg/kg BW) and blood samples were collected at specific intervals for 3 h total. In the crossbred heifers cortisol (P = 0.0560) and glucose (P = 0.0485) concentrations during the challenge were higher in temperamental relative to calm crossbred heifers. Insulin concentrations tended (P = 0.0737) to be higher in temperamental crossbred heifers. Cortisol (P = 0.0282) and glucose (P = 0.0011) concentrations were significantly higher in temperamental Brahman heifers. Insulin concentrations tended (P = 0.0793) to be greater for calm Brahman heifers. Temperamental cattle had a greater HPA axis response, which led to greater concentrations of cortisol and glucose, possibly because the glucose was being utilized differently by the temperamental cattle. Mature Brahman cow feed efficiency data was collected over two years, on two different cohorts of cows that had previous residual feed intake data as post-weaning heifers. In 2009 and 2010, 37 and 41 cows, respectively, in their first trimester of gestation were evaluated for RFI via the Calan gate system. Cows were fed 2.6% BW for 70 d with BW recorded weekly. Cows were classified according to their RFI values as either efficient or inefficient. Heifer RFI was not correlated to mature cow RFI based on assessment of the Pearson's correlation coefficient (r = -0.06, P = 0.57). This study indicates that establishment of RFI in heifers may not accurately predict their feed efficiency as mature cows.
Author: Mario Luiz Chizzotti Publisher: Brill Wageningen Academic ISBN: 9789086863402 Category : Animal nutrition Languages : en Pages : 0
Book Description
Variations in feeding frequency may lead to difference in utilization of dietary nutrients. The effects of feeding frequency have been tested in growing pigs and finishing pigs using respiratory quotient and postprandial kinetics of plasma metabolites. A reduced feeding frequency resulted in an increased lipogenesis and proteolysis shortly after the meal both in growing and finishing pigs. Nevertheless, growing and finishing pigs exhibit different metabolic pathways when feeding frequency is reduced.
Author: Michael Patrick Davis
Author: Mariana Medeiros Masiero
Author: Rodney A. Hill
Author: Colin G. Scanes
Author: Marcelo Hentz Ramos
Author: Wimberley K. Krueger
Author: Phillip Allan Lancaster
Author: Rodney A. Hill
Author: Brook Bradbury
Author: Mario Luiz Chizzotti