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Author: Andrea N. Loyd Publisher: ISBN: Category : Languages : en Pages :
Book Description
These studies were designed to evaluate the relationships between residual feed intake (RFI) and performance of growing heifers and Brahman cows. Residual feed intake was determined for 77 heifers of diverse breedtypes (Angus, Brahman, Hereford, Holstein, Jersey and F1 crosses) during both the pre- and post-pubertal periods. Heifers were individually fed and allowed ad libitum access to feed for 84 +/- 6 d during the prepubertal feeding trial and 90 +/- 4 d during the post-pubertal feeding trial. Brahmaninfluenced heifers had lower RFI than heifers without Brahman influence during both the pre-pubertal (P
Author: Andrea N. Loyd Publisher: ISBN: Category : Languages : en Pages :
Book Description
These studies were designed to evaluate the relationships between residual feed intake (RFI) and performance of growing heifers and Brahman cows. Residual feed intake was determined for 77 heifers of diverse breedtypes (Angus, Brahman, Hereford, Holstein, Jersey and F1 crosses) during both the pre- and post-pubertal periods. Heifers were individually fed and allowed ad libitum access to feed for 84 +/- 6 d during the prepubertal feeding trial and 90 +/- 4 d during the post-pubertal feeding trial. Brahmaninfluenced heifers had lower RFI than heifers without Brahman influence during both the pre-pubertal (P
Author: Robert O. Dittmar Publisher: ISBN: Category : Languages : en Pages :
Book Description
Objectives were to characterize residual feed intake (RFI) and determine the phenotypic correlation between performance, feed efficiency, and other biological measurements in Brahman heifers, as well as the relationship between RFI determined in confinement and measurements of grazing activity on pasture. Three separate 70 d feeding trials were performed, and RFI was determined as the residual between actual and predicted dry matter intake (DMI) for a given level of production. Brahman heifers (n = 103; 5-to-9 mo of age) were individually limit-fed a pelleted 12% CP complete ration daily in Calan gates. Weekly body weight (BW) and DMI data were collected, and predicted DMI was determined by linear regression of actual DMI on mid-test metabolic BW. Ytterbium chloride was used to evaluate digestive kinetics, and fecal samples were collected to determine fecal volatile fatty acids (VFA) concentration and determine apparent dry matter digestibility (DMD) utilizing acid insoluble ash as an internal marker. Measurements of temperament were evaluated on all heifers at weaning. High (n = 6) and low (n = 6) RFI heifers (Exp. I) grazed fescue and ryegrass to determine variation in grazing behavior, DMI, and apparent DMD. Data from all three experiments were pooled, and RFI was not correlated with average daily gain (ADG), DMI, BW, partial efficiency of gain, feed conversion ration, fecal VFA concentration, or any measures of temperament. There were no significant differences in digestive kinetics between the RFI efficiency groups. Fecal samples taken for acid detergent insoluble ash (ADIA) determination were not collected at frequent enough intervals to account for weekly variation in fecal ADIA concentration. Pasture measurements were not different between the efficiency groups for heifers evaluated for grazing behavior, as well as estimated intake as a proportion of BW, or apparent DMD. Results of this study suggest that Bos indicus cattle appear to have similar efficiency traits as Bos taurus and Bos indicus influenced cattle, making this measure of efficiency equally as valid for use in both types of cattle. This indicates that selection based on RFI can be made to increase feed efficiency without affecting ADG or BW in Brahman cattle.
Author: Kara J. Matheney Publisher: ISBN: Category : Languages : en Pages :
Book Description
The objectives of these studies were (1) evaluate the relationship between temperament, blood parameters, and performance in Brahman calves (n = 300); (2) evaluate the relationship between residual feed intake (RFI) and reproductive development in Brahman bulls (n = 41). Serum was collected at 24 h and d 21 to 24, and analyzed for total protein (TP) immunoglobulin G (IgG), and cortisol (CS). Calves were weighed at 24 h, weighed and evaluated for temperament using exit velocity (EV) at d 21 to 24, and at 28 d intervals thereafter. Beginning 28 d prior to weaning, and at 28 d intervals through 56 d post-weaning calves were evaluated for pen score (PS) used to calculate temperament score (TS = (EV+PS)/2). The average TS from 28 d prior to weaning and weaning was used to generate temperament groups; calves 1 SD below the mean being calm, those 1 SD above the mean being temperamental and all remaining classified as intermediate. Calf TS influenced WW (P = 0.04) and ADG from birth to weaning (P = 0.03). Serum TP at 24 h affected (P 0.05) WW and ADG from birth to weaning. Serum IgG at 24 h affected (P = 0.03) WW. Brahman bulls (n = 41) were evaluated for RFI, insulin-like growth factor I (IGF-I), temperament, reproductive development, and ultrasound carcass traits. Serum was collected at d 0 and d 70 of the feeding trial and analyzed for IGF-I. Bulls were classified as efficient, intermediate, or inefficient (RFI classification method I) and as efficient or inefficient (RFI classification method II). Bulls were evaluated for temperament at weaning using TS. Temperament influenced (P 0.05) IGF-I concentrations at d 0. Reproductive development was not affected (P 0.05) by TS. Residual feed intake classification did not influence (P 0.05) age at reproductive milestones. Ultrasound carcass traits were not affected by TS or RFI. Serum TP at 24 h was a viable indicator of future growth performance. Temperamental animals had lower growth rates in both studies. Reproductive development was not affected by RFI. BW at reproductive milestones was lower in temperamental bulls.
Author: Aimee Hafla Publisher: ISBN: Category : Languages : en Pages :
Book Description
The objectives of this study were to characterize residual feed intake (RFI) in growing bulls and heifers and in mid-gestation females to examine relationships with performance, body composition, feeding behavior, digestibility (DMD) and heart rate (HR) and evaluate the impact of RFI on bull fertility and cow forage utilization. Additionally, use of the n-alkane method to predict individual animal variations in intake was investigated. To accomplish these objectives, multiple RFI studies were conducted. In all studies RFI was computed as the difference between actual and expected DMI from linear regression of DMI on mid-test metabolic BW and ADG. To evaluate phenotypic relationships between feed efficiency, scrotal circumference (SC) and semen-quality an experiment was conducted with yearling bulls (N=204). Residual feed intake was not correlated with BW and ADG, but was positively associated with 12th-rib back fat (BF) such that the more efficient bulls were leaner. Bulls with low RFI had similar SC and progressive motility of sperm compared to high-RFI bulls. However percent normal sperm were weakly associated with RFI in a negative manner. To examine phenotypic relationships between heifer postweaning RFI, and performance, efficiency, HR, and DMD of mid-gestation cows, RFI was measured in growing Bonsmara heifers (N=175). Forty-eight heifers with divergent RFI were retained for breeding. Subsequently, intake, performance and feeding behavior was measured on mid-gestation females. Pregnant females classified as having low postweaning RFI continued to consume 22% less feed, spent 25% less time eating, and had 7% lower HR while maintaining similar BW, ADG and body composition compared to high RFI females. A moderate association between RFI in growing heifers and subsequent efficiency of forage utilization in pregnant cows was found. Growing heifers identified as efficient had greater DMD, however DMD in mature cows was similar between RFI groups. The n-alkane method of predicting intake detected differences in intake between divergent RFI groups in mid-gestation females. Results from this study indicate that inclusion of RFI as a component of a multi-trait selection program will improve feed efficiency of growing animals and mid-gestation females with minimal impacts on growth, body composition, and fertility traits.
Author: Glenda Marie Bingham Publisher: ISBN: Category : Languages : en Pages :
Book Description
The objective of this study was to determine if feeding behavior traits are correlated with performance and feed efficiency traits in growing heifers. Individual dry matter intake (DMI) was measured in Brangus heifers (n = 115) fed a roughage-based diet (ME = 2.1 Mcal/kg) for 70 d using Calan gate feeders (6 heifers/pen). Residual feed intake (RFI) was computed as the residuals from linear regression of DMI on mid-test BW0.75 and average daily gain (ADG). Heifers with the highest (n = 18) and lowest (n = 18) RFI were identified for feeding behavior measurements. During days 28 through 56 of the 70-d feeding trial, continuous video recordings were obtained for all heifers. Video images of two sets of four 24-h periods, two weeks apart, were analyzed for the focal animals. All occurrences of feeding were timed and counted per day, and the eight 24-h periods averaged to derive the overall feeding event (FE) and meal duration and frequency for each focal heifer. Total feeding event duration was defined as the total min per day the animal0́9s head was down in the feed bunk. A meal included all visits an animal made to the feed bunk that were separated by less than 5 min. The mean RFI values for the low and high RFI heifers were (mean " SE) - 1.03 and 1.00 " 0.03 kg/d, respectively. Low RFI heifers consumed 21.9% less (P
Author: Egleu Diomedes Marinho Mendes Publisher: ISBN: Category : Languages : en Pages :
Book Description
The first objective of this study was to validate the feeding behavior measurements from a radio frequency electronic system (GrowSafe (TM) System Ltd., Airdrie, AB, Canada) and examine the software sensitivity to different parameter settings (MPS) to quantify feeding behavior traits. Data was continuously recorded 24 h per day using the GrowSafe (TM) system for 32 heifers over 81-d. Ten animals were randomly selected and evaluated over 6-d using time-lapse video recordings. Different parameter settings (MPS) from the electronic system (GrowSafe (TM)) used to record feeding behavior data, bunk visits (BV) frequency and BV duration, were compared with the observed (video) values. The second objective of this study was to quantify meal criterion; examine the associations between feeding behavior traits, performance, and feed efficiency; and the effects of breed type on feed efficiency (residual feed intake - RFI) and feeding behavior traits in heifers fed high-grain diets. Results from study one demonstrated that the GrowSafe (TM) system 4000E could accurately predict BV and meal data compared to observed data. The 100 s, used for the maximum duration between consecutive EID recordings to end an uninterrupted BV, was the appropriate MPS to predict BV frequency and duration, and meal frequency and duration compared to observed data using the GrowSafe (TM) 4000E system. The system's ability to detect the animal's presence or absence at the feed bunk was 86.4 and 99.6 percent, respectively. Results from the second study demonstrated that the meal criterion for heifers fed high-grain diets was 13.8 min. The 4 methods to calculate meal criterion demonstrated no differences in results of frequencies and durations of meal and the number of bunk visits per meal. Similar phenotypic correlations were found between the feeding behavior traits with RFI derived from the base model or with adjustments for final back fat. The adjustment of RFI to final back fat changed the RFI rank between breeds. The addition of feeding behavior traits to the RFI base model could accounted up to 40.4 percent of the variation in DMI not explained by ADG or MBW.
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: Andrea N. Loyd
Author: Andrea N. Loyd
Author: Robert O. Dittmar
Author: Kara J. Matheney
Author: Gustavo Durante Cruz
Author: Aimee Hafla
Author: Glenda Marie Bingham
Author: Egleu Diomedes Marinho Mendes
Author: Rodney A. Hill
Author: Dixon D. Hubbard
Author: