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PubMed2001

Genetic and phenotypic variance and covariance components for feed intake, feed efficiency, and other postweaning traits in Angus cattle.

Records on 1,180 young Angus bulls and heifers involved in performance tests were used to estimate genetic and phenotypic parameters for feed intake, feed efficiency, and other postweaning traits. The mean age was 268 d at the start of the performance test, which comprised 21-d adjustment and 70-d test periods. Traits studied included 200-d weight, 400-d weight, scrotal circumference, ultrasonic measurements of rib and rump fat depths and longissimus muscle area, ADG, metabolic weight, daily feed intake, feed conversion ratio, and residual feed intake. For all traits except the last five, additional data from the Angus Society ofAustralia pedigree and performance database were included, which increased the number of animals to 27,229. Genetic (co)variances were estimated by REML using animal models. Direct heritability estimates for 200-d weight, 400-d weight, rib fat depth, ADG, feed conversion,and residual feed intake were 0.17 +/- 0.03, 0.27 +/- 0.03, 0.35 +/- 0.04, 0.28 +/- 0.04, 0.29 +/- 0.04, and 0.39 +/- 0.03, respectively. Feed conversion ratio was genetically (r(g) = 0.66 ) and phenotypically (r(p) = 0.53) correlated with residual feed intake. Feed conversion ratio was correlated (r(g) = -0.62, r(p) = -0.74) with ADG, whereas residual feed intake was not (rg = -0.04, r(p) = -0.06). Genetically, both residual feed intake and feed conversion ratio were negatively correlated with direct effects of 200-d weight (r(g) = -0.45 and -0.21) and 400-d weight (r(g) = -0.26 and -0.09). The correlations between the remaining traits and the feed efficiency traits were near zero, except between feed intake and feed conversion ratio (r(g) = 0.31, r(p) = 0.23), feed intake and residual feed intake (r(g) = 0.69, r(p) = 0.72), and rib fat depth and residual feed intake (r(g) = 0.17, r(p) = 0.14). These results indicate that genetic improvement in feed efficiency can be achieved through selection and, in general, correlated responses in growth and the other postweaning traits will be minimal.

Adipose Tissue↗

PubMed1986

Comparative feed efficiency of Holstein and Jersey cows.

Feed efficiency measures, gross energy (solids-corrected milk/estimated energy intake), N (milk N/N intake) utilization, and apparent digestibilities of ration dry matter and N were calculated for 34 daughters of 21 Holstein and 29 daughters of 18 Jersey sires in first and second trimesters of lactation. Cows were studied in N balance trials and were fed ad libitum corn silage-based, complete rations formulated to meet average nutrient requirements. The objective was to determine whether these breeds differ in rates of converting dietary protein or energy to milk protein or milk energy. Holstein and Jersey did not differ for digestibility of ration dry matter in either trimester of lactation. They also converted dietary protein to milk protein at similar rates. Energy efficiencies of Holstein and Jersey did not differ in first trimester, but Holstein exceeded Jersey in second trimester. Because intake of dry matter by Jersey increased about 4% from first to second trimester (opposite of Holstein) and N balance was higher than for Holstein, Jersey cows may have been repleting more adipose tissue. We suggest no comparative advantage for Jersey in spite of higher ratios of milk to body weight and feed intake less than Holstein.

Animals↗

PubMed1979

[T4 metabolism in age matched heavy and light rats with good and bad feed efficiency following high- or low-in-fat diet].

Rats, fed two diets (high or low in fat content), were at the and of the feeding-period separated in light and in heavy animal groups. The leaner rats from the diet group high in fat content show opposite to the heavier animals of this diet group significantly increased T4 distribution spaces, significantly shortened T4 half life time and lower feed efficiency. T4 serum values, absolute T4 degradation per day and body mass and free thyroxine index in these leaner rats also increased significantly. However comparing heavy rats feed a diet low and light rats fed a diet high in rat content the latter show also a decreased feed efficiency, but no differences in T4 serum concentration or T3 binding capacity of serum proteins, free thyroxine index and T4 degradation. The results in T4 metabolism are discussed in relation to feed efficiency of the investigated animal groups.

Animals↗

PubMed1991

Research note: Maxiban effects on heat-distressed broiler growth rate and feed efficiency.

One study was conducted utilizing 192 male broilers, at 4 to 7 wk posthatching, to evaluate a narasin-nicarbazin drug combination (Maxiban) for effects on bird growth rate, feed efficiency, and survivability during cycling ambient temperature (24 to 35 C) distress. Maxiban did not impact (P greater than .1) live weight gain, but reduced (P less than .05) gain:feed ratio (unadjusted for mortality), from .29 for controls to .21 as bird survivability declined (P less than .05) from 87.5 to 69.8%. Adjusting feed efficiency by adding the gain of birds dying of heat prostration to that for birds surviving the experiment resulted in feed efficiency for Maxiban-supplemented birds being similar (P = .48) to birds not consuming Maxiban. Under the conditions of the present study, Maxiban increased the mortality rate of male broilers exposed to cycling ambient temperature of 24 to 35 C during 4 to 7 wk posthatching.

Animals↗

PubMed2005

Glutathione and respiratory chain complex activity in duodenal mitochondria of broilers with low and high feed efficiency.

We previously observed increased reactive oxygen species (ROS) production in intestinal mitochondria obtained from broiler breeder males with low feed efficiency (FE, gain-to-feed). Because antioxidants are critical for combating ROS-mediated oxidative stress and preserving mitochondrial function, the objectives of this study were 1) to determine levels of reduced glutathione (GSH), a major antioxidant in mitochondria, 2) to measure activities of GSH recycling enzymes: GSH peroxidase and GSH reductase, and 3) to establish relationships between antioxidants and respiratory chain complex activities (complexes I, II, III, IV, and V) in broiler breeder males with low and high FE. Duodenal mitochondria were isolated from broilers with low (0.62 +/- 0.01, n = 8) and high (0.80 +/- 0.01, n = 8) FE. Activities of respiratory chain complexes, GSH peroxidase, and GSH reductase, and levels of GSH were measured by UV spectrophotometry. There were no differences in GSH peroxidase or reductase activities or in individual complex activities between groups but GSH levels tended to be higher (P = 0.075) and oxidized to reduced glutathione ratio tended to be lower (P = 0.077) in broilers with high FE. Regression analysis revealed significant correlations (P < or = 0.05) between mitochondrial GSH and activities of complexes II, IV, and V with R2 values of 0.35, 0.56, and 0.49, respectively. These data suggest that GSH may be important in maintaining or enhancing the activity of certain respiratory chain complexes and could be involved in the phenotypic expression of feed efficiency in broilers.

Animals↗

PubMed1984

Effects of breed and intake level on growth and feed efficiency in ram lambs.

Effects of breed and intake level on growth and feed efficiency in ram lambs were tested with 52 Rambouillet, 46 Dorset and 53 Finnish Landrace (Finn) rams. Rams were individually fed at 100, 85 or 70% of ad libitum or at maintenance. The experimental diet contained 79% digestible dry matter (DM), 3.28% N and 2.95 Mcal metabolizable energy/kg DM. Rams were serially slaughtered every 35 d for 175 d. The efficiency of deposition of body weight, protein, energy and trimmed cuts was determined by breed and intake level over constant time, weight, fat and maturity intervals. Ranking of the breeds for feed efficiency depended upon both the interval and the criterion of evaluation. Efficiency of protein and trimmed cut gain was positively related to mature size in the time and weight intervals, but all differences in efficiency were small in the fat or maturity intervals. Gross energetic efficiency did not differ greatly among breeds in any interval. Dorsets appeared to have a somewhat greater propensity to fatten than the other breeds and to be less able to retain N at a fixed N intake. In the constant time interval, maintenance requirements were estimated to be 115 kcal/kg.75, and the estimated partial efficiencies of energy deposition in fat and protein were .49 and .26, respectively.

Animal Feed↗

PubMed1989

Changes in feeding efficiency and carcass composition in rats on repeated high-fat feedings.

Male and female Sprague-Dawley rats were fed ad libitum two cycles of 10 weeks of a high-fat (HF) diet, followed by 5 weeks of control chow (CH). During the initial 10 weeks (weeks 1-10) the HF fed male rats had an increased rate of weight gain and feeding efficiency (FE) in comparison to CH-fed controls. In the female HF-fed rats, the FE was higher during weeks 1-5 than that seen in CH-fed females. The male HF-fed rats had significantly higher levels of FE than the female HF-fed rats during the first 10 week period. At the end of the tenth week, the HF-fed rats weighed significantly more than CH-fed controls. HF-fed male rats gained more weight than HF-fed female rats. During the 5 week period (weeks 11-16) of CH feeding, the body weight of the HF-fed rats was reduced. At the end of week 16 there was no difference between the body weights of the CH and HF fed rats. During the second cycle of HF feeding (weeks 16-25) the HF-diet further increased body weight gain in both male and female rats compared with CH-fed controls. There was no reduction in FE in HF-fed male and female rats during this period when compared to the first ten week HF feeding period. After the last 5 week period (weeks 26-30) of CH feeding, the formerly HF-fed rats had similar body weights as the control rats, but still had more body fat than control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1985

Relationship between activity at a young age and feed efficiency in chickens.

Feed conversions of three Ottawa strains of Leghorns were measured from hatch to 27 days and bird activity at 1, 2, and 4 weeks of age was assessed. Males were more active than females. Chicks of the more active strain consumed more feed and had poorer conversion than those from the least active strain. Ranking of the strains on feed conversion to 27 days was similar to their ranking on feed consumed per egg mass produced in an earlier study.

Age Factors↗

PubMed1988

Effects of selection for body size on feed efficiency and size of Holsteins.

First lactation records from a herd of Holstein cows bred for either high production and large size or for high production and small size were examined to estimate effects of selection for size and feed efficiency. Selection was among progeny-tested bulls available from the artificial insemination industry. Three rations were fed that differed for ratios of concentrate to milk. After three generations, groups of cows bred for large or small size differed by 50.2 kg in weight, 5.6 cm in wither height, 6.4 cm in length, 2.1 cm in depth, and 5.9 cm in chest circumference; most differences were due to a decrease in the size of the small cows. On the basis of total lactations, cows bred for small size were 2.8% more feed efficient than cows bred for large size. During the first 90 d of lactation cows fed the low concentrate ration were more efficient than those fed the high concentrate ration. Season of calving had an effect on feed efficiency between d 30 and 120 of lactation. During this period cows calving between December and May were more efficient.

Animal Nutritional Physiological Phenomena↗

PubMed2003

Dietary protein to metabolizable energy ratios on feed efficiency and structural growth of prepubertal Holstein heifers.

Sixty Holstein heifers, 124.5 +/- 1.1 d of age and 124.9 +/- 2.5 kg of BW, were used to evaluate the influence of dietary crude protein to metabolizable energy ratio (CP:ME) on feed efficiency, structural growth, and body condition score. Treatment rations containing a specific CP:ME ratio were assigned to heifers in a complete randomized block design with treatment periods lasting 20 wk. The CP:ME ratios were 48.3, 59.1, 67.5, and 76.5 g of CP per Mcal of ME. The CP:ME ratios were altered by adjusting the concentration of CP (12.0,15.2, 17.4, and 19.7% CP) with similar amounts of ME (2.6 Mcal/kg DM) across all treatment rations. BW was recorded weekly on two consecutive days and used to adjust dry matter intake to allow approximately 0.80 kg/d gain. Average daily gain did not differ between the treatment rations, 0.74, 0.81, 0.81, 0.77 kg/d, low to highest CP:ME ratio, respectively. Dry matter intake showed a quadratic effect for the treatment rations, 3.30, 3.41, 3.48, and 3.39 kg/d, low to highest CP:ME ratio, respectively, and averaged 2.0% BW. Feed efficiency improved linearly with increasing CP:ME ratios, 4.76, 4.42, 4.35, and 4.33, respectively. The increased CP:ME ratios were accompanied by increasing levels of plasma urea N, 9.88, 13.34, 14.94, and 16.57 mg/dl, respectively. A trend toward linear increases in wither and hip height growth resulted with increasing CP:ME. Hip width growth was quadratic with increasing CP:ME ratios. Observed linear effects in feed efficiency and some structural growth measurements demonstrate positive results when feeding CP:ME ratios >48.3 to Holstein heifers between 125 and 234 kg of BW and gaining 0.80 kg/d.

Animal Nutritional Physiological Phenomena↗

PubMed1984

Weight gain and feed efficiency of chicks fed sucrose fatty acid esters.

Day-old Hubbard X Hubbard broilers (mixed sexes) were fed for 2 weeks with a basal diet containing 5% experimental carbohydrate. The experimental carbohydrates were one of the following: sucrose fatty acid esters (SFE)-high monoesters (SFE 1670), SFE-low monoesters (SFE 370), sucrose, glucose, or cellulose. Feed efficiency, weight gain, and growth performance were compared among treatments. Chicks fed 5% SFE 1670 showed significantly less (P less than .01) weight gain and feed efficiency than chicks fed other experimental carbohydrates. There were no significant differences (P less than .01) in weight gain and feed efficiency among groups of chicks fed SFE 370, sucrose, glucose, or cellulose. Most of the chicks fed SFE 1670 were small in size, had poor feathering, and excreted reddish-brown droppings. The appearance and droppings obtained from chicks fed SFE 370 were similar to the appearance and droppings from chicks fed sucrose, glucose, and cellulose. The SFE that contained a large proportion of monoesters (SFE 1670) resulted in poor growth of chicks, whereas SFE containing a small proportion of monoesters (SFE 370) resulted in growth performance similar to chicks on control diets.

Animals↗

PubMed1985

Effect of monensin and tylosin on average daily gain, feed efficiency and liver abscess incidence in feedlot cattle.

Fourteen trials were conducted to evaluate the effects of feeding monensin at 33 ppm alone, tylosin at 11 ppm alone and the two feed additives in combination on the average daily gain, average daily feed intake, feed:gain ratio and the incidence of liver abscesses in feedlot cattle. Monensin reduced feed intake and improved feed efficiency (P less than .05), and had no effect on average daily gain. Tylosin improved average daily gain (P less than .05) and had no effect on daily feed intake. The effect of tylosin on feed efficiency approached significance. The interaction of monensin and tylosin was nonsignificant for daily gain, daily feed intake and feed:gain ratio. Monensin had no effect on liver abscess incidence, while tylosin reduced abscess incidence from 27 to 9%.

Animal Feed↗

PubMed1991

Comparison of rabbit breed types for postweaning litter growth, feed efficiency, and survival performance traits.

Postweaning data on 643 rabbits from 122 litters representing four breed types, New Zealand White (NZW) and Californian (CAL) purebreds, CAL X NZW (CXN), and Flemish Giant (FG) crossbreds (the latter group was a collection of FG X CAL, FG X Champagne D'Argent [CHA], and 1/2 FG X 1/4 CAL X 1/4 CHA), were gathered over five seasons and compared for growth, feed efficiency, and survival-related performance traits. Evaluation criteria included litter size and weight at weaning (28 d); 28- to 70-d litter feed intake, weight gain, feed efficiency, and mortality rate; and litter and average market weight (70 d). The least squares model included main effects of breed type, season of birth of the litter and parity of dam, litter size at weaning as a linear covariate, and the random error. Breed-type differences were not detected for litter size and weight at weaning and feed efficiency. Purebred NZW and CAL litter trait performances were comparable (P greater than .05). Purebred NZW litters consumed less feed than CXN and FG crosses, gained weight less rapidly than FG crosses, and weighed less per fryer at 70 d than CXN and FG crosses (P less than .05). Feed intake was lower and average market weight was lighter for CAL purebred litters than for CXN and FG crossbred litters (P less than .05). The CXN and FG crossbreds only differed (P less than .05) for average market weight (2,078 vs 2,192 g). Mortality rate was lower (P less than .05) in CXN crossbred litters than in CAL purebred litters.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1983

Effects of diet and bacitracin on growth, feed efficiency, and populations of Clostridium perfringens in the intestine of broiler chicks.

Experiments were conducted to demonstrate the activity of bacitracin as a growth permittant for poultry and to further elucidate the mode of action of antimicrobial agents for that purpose. Supplementing a soybean protein and sucrose-based diet with 2.2, 11, and 55 ppm of bacitracin resulted in significant improvements in weight gain and feed efficiency of chicks fed the higher levels. In a second experiment, graded levels of bacitracin from 1.1 to 55 ppm were fed. A regression analysis of the index scores, the combined effects of both weight gain and feed efficiency, on the log of the significant dose levels of 5.5 to 27.5 ppm gave a linear response line with r = .996. Based on the equation, the ineffective level of the antibiotic was determined to be 4 ppm and the maximum effective level 31 ppm. Supplementing the soybean protein and sucrose-based diet with levels of 5.5, 16.5, and 55 ppm of bacitracin reduced the numbers of Clostridium perfringens organisms in ileal contents of chicks (all P less than .05). Chicks fed a level of 1.1 ppm, a level that did not give a growth response, had numbers of the organism present that were not significantly different from controls. Supplementing a soybean meal and corn-based diet with a level of 55 ppm of bacitracin did not significantly affect weight gain, feed efficiency, or numbers of C. perfringens in the ileum of chicks.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Effect of feed restriction on feed efficiency and incidence of sudden death syndrome in broiler chickens.

An experiment was conducted to determine the effect of feed restriction on the incidence of sudden death syndrome (SDS). Body weight, feed efficiency, and incidence of SDS were compared for broilers fed ad libitum and broilers restricted in feed intake by 25%. Six pens of 50 male broilers were fed commercial-type texture diets ad libitum, and six pens of birds were restricted to 75% of this intake from 5 to 39 days of age. Growth rate and the incidence of SDS were significantly higher in ad libitum-fed broilers. Feed efficiency was better in the ad libitum-fed group up to 11 days of age and then became similar to that of the restricted group. Results support the hypothesis that the incidence of SDS is related to growth rate and suggest that SDS mortality may be reduced by growing broilers at a slower rate.

Animal Nutritional Physiological Phenomena↗

PubMed1985

Effects of sodium diacetate on the growth, feed efficiency, and intestinal microflora of broilers.

Three levels of sodium diacetate (.625, 1.25, and 3.75 g/kg diet) were incorporated into the diets of day-old broiler chicks. A control ration and a 20 mg/kg aureomycin ration were fed to additional groups of chicks. Each treatment contained 40 chickens at 3 weeks; the number was reduced to 20 chickens at 5 and 8 weeks. At 3 and 8 weeks of age, the large and small intestines of 5 chickens from each treatment were examined for selected microorganisms. Chick growth and feed efficiency were also recorded. The entire experiment was run twice, but in Trial 2 the lowest level of sodium diacetate treatment was replaced by a combination of sodium diacetate (.625 g/kg diet) and aureomycin (20 mg/kg diet). No improvement in the rate of growth was found in the sodium diacetate-treated groups, although additional weight gain was detected in aureomycin-fed groups at 2 weeks of age. Improved feed efficiency in the treated groups (sodium diacetate and aureomycin) was observed in both trials at 2 weeks and at 3 weeks of age in Trial 1. No feed efficiency effects were observed after that time. The sodium diacetate-fed groups showed an increased lactobacilli population in the small intestine along with a concurrent decrease in streptococci. The effect of sodium diacetate in reducing total coliforms in the large intestine was more obvious at 3 weeks than at 8 weeks. Aureomycin appeared to suppress the population of lactobacilli and total coliforms in this study. A combination of sodium diacetate and aureomycin failed to exhibit a synergistic effect either on the growth rate or on the intestinal microflora.

Acetates↗

PubMed2006

Test duration for growth, feed intake, and feed efficiency in beef cattle using the GrowSafe System.

This study was conducted to determine the optimum test duration and the effect of missing data on accuracy of measuring feed efficiency and its 4 related traits ADG, DMI, feed conversion ratio, and residual feed intake in beef cattle using data from 456 steers with 5,397 weekly averaged feed intakes and BW repeated measurements taken over 91 d. Data were collected using the GrowSafe System at the University of Alberta Kinsella Research Station. The changes and relative changes in phenotypic residual variances and correlations (Pearson and Spearman) among data from shortened test durations (7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, or 84 d) and a 91-d test were used to determine the optimum test duration for the 4 traits. The traits were fitted to a mixed model with repeated measures using SAS. Test durations for ADG, DMI, feed conversion ratio, and residual feed intake could be shortened to 63, 35, 42, and 63 d, respectively, without significantly reducing the accuracy of the tests when BW was measured weekly. The accuracy of the test was not compromised when up to 30% of the records were randomly removed after the first 35 d on test. These results have valuable and practical implications for performance and feed efficiency testing in beef cattle.

Animals↗

PubMed1997

Influence of undergradability of protein in the diet on intake, daily gain, feed efficiency, and body composition of Holstein heifers.

Thirty-two Holstein heifers with body weights (BW) between 213 and 231 kg were randomly assigned to one of four treatments for the 50-d trial. Treatments consisted of four percentages of rumen-undegradable protein (RUP) (31, 43, 50, and 55% of total N) at 100% of National Research Council recommendations for total digestible nutrients and crude protein. Total mixed diets composed of corn silage, ground barley straw, soybean meal, blood meal, urea, and minerals were formulated for a mean daily BW gain of 0.60 kg. Ration RUP percentage was varied by shifting protein sources. Mean dry matter intake (grams per kilogram of BW0.75) was 97.6, 84.4, 77.8, and 73.5 for 31% RUP (soybean meal), 43% RUP (blood and soybean meal), 50% RUP (blood meal with urea), and 55% RUP (blood meal) treatments, respectively. Daily gain was 0.84, 0.89, 0.91, and 0.96 kg/d, respectively. Intake of digestible energy (megacalories per kilogram of BW0.75 per day) was 0.28, 0.24, 0.22, and 0.21, respectively, and feed efficiency (megacalories of digestible energy per kilogram of BW gain) was 20.6, 16.1, 15.2, and 13.3, respectively. Dry matter intake (grams per kilogram of BW0.75), digestible energy intake, feed efficiency, daily BW gain, and hip height differed with respect to treatment. There were no differences in growth, wither height, or heart girth because of treatments. Changes in percentage of empty body fat as estimated by urea space procedures was 6.73, 4.67, 6.67, and 7.32, respectively, and did not differ with respect to treatments. These results indicate that increasing the RUP percentage in the diets of growing heifers improves feed efficiency and increases BW gain.

Animal Feed↗