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At least 127 records · Page 7Linked to original sources
PubMed1992

Effects of stable flies (Diptera: Muscidae) and heat stress on weight gain and feed efficiency of feeder cattle.

Cattle respond to the feeding of stable flies, Stomoxys calcitrans (L.), by bunching to protect their front legs. This bunching can increase heat stress which indirectly accounts for much of the reduction in cattle weight gains. We used fly-screened, self-contained feedlot pens which allowed regulation of fly populations feeding on cattle. The indirect fly effects (bunching and heat stress) accounted for 71.5% of the reduced weight gain. The direct effect of the biting flies and energy loss involved in fighting flies accounted for 28.5% of the reduced weight gain.

Animals↗
PubMed1991

Biological type effects on postweaning growth, feed efficiency and carcass characteristics of steers.

Postweaning growth, feed consumption and carcass characteristics of 259 individually fed F1 Angus-, Red Poll-, Pinzgauer-, Simmental- and Tarentaise-sired steers from Hereford dams were compared. Average daily gain to 382 d of age for Simmental-sired steers exceeded (P less than .05) the ADG for Red Poll, Angus and Pinzgauer, which were not different. Tarentaise-sired steers were intermediate in growth rate. Simmental-sired steers required less (P less than .05) feed per kilogram of gain than Red Poll- and Angus-sired steers to reach either 382 d of age or 400 kg. Feed conversion (FC) by Simmental, Pinzgauer and Tarentaise-sired steers did not differ (P greater than .05), nor did FC by Red Poll- and Angus-sired steers to reach 382 d or 400 kg. Angus-sired steers required less ME per kilogram of gain to reach 12.7 mm of carcass backfat than did Red Poll-, Pinzgauer- or Tarentaise-sired steers, which were similar. Simmental-sired steers were intermediate in feed conversion to 12.7-mm fat depth and did not differ from the other breed groups. Rankings of breed groups for traits indicative of lean tissue growth were similar to rankings for live animal growth traits. At age- and weight-constant endpoints, Angus-sired steers had more (P less than .05) fat cover and marbling than did steers sired by the other breeds. At these endpoints, Red Poll-sired steers also had more (P less than .05) fat cover than did Pinzgauer-, Simmental- and Tarentaise-sired steers, which were similar.

Adipose Tissue↗
PubMed2004

Components of feed efficiency in broiler breeding stock: influence of water intake and gastrointestinal contents.

An experiment was conducted with 3 lines of broilers to evaluate the potential roles of water intake and fill of the gastrointestinal (GI) tract on feed conversion ratio (FCR) as measured in a 1-wk FCR test. Birds were reared to juvenile selection age (41 d) and subsequently selected, with the best 18 to 29% of male chicks placed into cages for FCR testing. Feed and water intake were highly correlated in all lines, with each in turn highly correlated with weight gain on test. Although filling of the GI tract differed between the top and bottom halves of the FCR distribution, FCR as measured and corrected for weight of GI tract contents were highly correlated (r = 0.59 to 0.93). Differences between FCR classes were striking for weight gain, but differences between FCR class groups were subtle for starting weight and feed intake. These subtle differences are difficult to detect in a single generation, but may add up through generations of selection. Based on the results of the current and previous studies, it appears that selection for improved FCR works at multiple levels to improve efficiency of feed conversion in broiler breeding stock.

Animal Feed↗
PubMed2004

Components of feed efficiency in broiler breeding stock: the use of fasted body temperature as an indicator trait for feed conversion in broiler chickens.

Five trials were conducted to evaluate the usefulness of body temperature (BT) measured under conditions of mild handling stress as an indicator trait for feed conversion ratio (FCR) in broilers. The trials used males from 4 lines of broilers (a randombred control population and 3 heavy broiler lines). Birds were reared to approximately 6 wk of age and then selected for FCR testing based upon BW and conformation. At the start of the FCR test, birds were fasted for periods lasting from 18 to 48 h, and their BT were measured, which was followed immediately by initiation of an FCR test lasting 1 wk. The correlation between FCR and BT was significant in only 2 of the 5 trials. Differences between good and poor converters were generally attributed to greater gains of BW on similar amounts of feed intake. The results of the current trials indicate gain on test is the primary factor affecting FCR and that BT is not a reliable predictor of FCR.

Animal Feed↗
PubMed1989

Feeding efficiency of premature neonates.

The purpose of this study was (a) to investigate the validity of the revised Neonatal Oral Motor Assessment Scale (NOMAS) in discriminating between efficient and inefficient feeders in a sample of high-risk premature neonates and (b) to identify significantly different oral motor behaviors in the two groups. The revised NOMAS rates normal and abnormal characteristics of nutritive and nonnutritive sucking. The 26 subjects were classified by the amount of liquid they consumed during the first 5 min of feeding. The findings demonstrated that both nutritive and nonnutritive sucking scores were higher in the efficient feeders than in the inefficient feeders and that the revised NOMAS scores accurately classified the two groups. Characteristics that were significantly associated with inefficient feeding were lack of rhythm, disorganization in jaw and tongue movements, and pauses of more than 6 sec. Often, these responses appeared to be related to respiratory patterns.

Bottle Feeding↗
PubMed1990

Growth, feed efficiency and carcass composition of finishing Friesian steers fed the beta-adrenergic agonist L-644,969.

The beta-adrenergic agonist L-644,969 was evaluated to determine its effects on growth performance and carcass composition of Friesian steers. L-644,969 is the R,R isomer of 6-amino [[(1-methyl-3-phenylpropyl) amino] methyl]-3-pyridine methanol dihydrochloride. Four groups of 18 steers, averaging 380 kg body weight, were individually given ad libitum access to a pelleted concentrate diet that contained either 0, .25, 1.0 or 4.0 ppm L-644,969 for the final 12 wk of the finishing period. Live weight gain was not affected by L-644,969, but feed consumption was linearly reduced (5.5, 6.3 and 15.7%; P less than .01) and feed conversion efficiency was linearly increased (16, 25 and 31%; P less than .01) relative to unmedicated controls, respectively. In addition, L-644,969 quadratically increased carcass weight (3.7, 9.3 and 8.5%; P less than .01) and dressing percentage (2.7, 7.9 and 7.9%; P less than .001). The proportion of trimmed fat in the carcass was quadratically reduced (14.5, 29 and 36%; P less than .001) and yield of lean meat quadratically increased (6.7, 13 and 15.6%; P less than .001). beta-adrenergic agonist treatment altered the distribution of lean meat such that a greater (P less than .001) proportion of the total lean was in the hind portion of carcasses from treated animals. Based on these findings, we suggest that L-644,969 may have utility as an agent to improve efficiency of production of lean beef.

Adrenergic beta-Agonists↗
PubMed1981

Effects of dietary fat on feed efficiency, reproductive performance, and in vitro lipogenesis by the turkey hen.

Two 16-week feeding trials were conducted with Large White turkey hens to determine the effect of graded energy levels (as fat-6, 18, 30, and 42% substituted isocalorically for corn meal) on energy efficiency, reproductive performance, lipogenic enzyme activity, and in vitro lipogenesis. A constant calorie: gram-protein ratio (17:1) was maintained for all dietary treatments. Also, other components of the diets were adjusted to maintain constant energy-to-nutrient ratios. Additional fat increased (P less than .05) energy utilization but had no effect on reproductive performance. Additional fat calories decreased (P less than .05) malic enzyme, isocitrate dehydrogenase, and fatty acid synthetase activities; however, fatty acid synthetase activity was the most responsive of the three enzymes to 42% metabolizable energy as fat. Liver lipid content was also decreased (P less than .05) by additional fat calories. In vitro lipogenesis (fatty synthesis from 10 mM (1-14C) sodium acetate) was also decreased (P less than .01) by additional dietary fat.

Animal Feed↗
PubMed1997

Optimum postweaning test for measurement of growth rate, feed intake, and feed efficiency in British breed cattle.

The optimum duration of test for measurement of growth rate, feed intake, feed conversion, and residual feed intake was examined using postweaning feed intake and weight data from 760 Angus, Hereford, Polled Hereford, and Shorthorn heifer and Angus bull progeny from 78 sires. Variance components, heritability, phenotypic and genetic correlations, and the efficiency of selection using shortened tests compared with a 199-d test were used as criteria to assess the optimum test length. The results indicated that a 35-d test was sufficient for measurement of feed intake, whereas a 70-d test was required to measure growth rate, feed conversion, and residual feed intake without compromising the accuracy of measurement. When a 70-d test is used to measure growth rate, feed conversion, and residual feed intake there is minimal loss in accuracy when weights are collected every 2 wk instead of weekly, but a further increase in the interval between weights to 5 wk caused a decline in the accuracy of the test. Therefore a 70-d test with cattle weighed every 2 wk seems to be optimal for measuring these traits in British breed cattle.

Animal Feed↗
PubMed2006

Feeding time and feeding rate and its relationship with feed intake, feed efficiency, growth rate, and rate of fat deposition in growing Duroc barrows.

Because feed is the major cost to pork production, management practices and breeding strategies are aimed at optimizing feed intake. Knowledge about the shape of feed intake and feeding behavior curves may be of interest for optimization of lean meat production. This study investigated trends based on daily measurements of feeding behavior in 200 Duroc barrows, originating from 5 sires and 200 dams, during growth. Daily values were examined between 88 and 188 d of age. Furthermore, phenotypic correlations between feeding length and feeding rate, and feeding frequency, feed intake, residual feed intake, growth rate, and rate of fat deposition were investigated for a period between 95 and 175 d of age. No differences were observed between sires for parameter estimates of a curvilinear function fitted to data on feeding length as a function of age, but the effect of sire was significant (P < 0.01) for values at individual ages up to 132 d of age. Feeding rate (feed ingested for each minute spent eating) increased in a linear fashion with age (average R(2) = 0.80) and differently so for different sires (P < 0.05 for the intercept and P < 0.01 for the regression coefficient). Because the increase in BW is linear over this time period (average R(2) = 0.99), the results suggest that feeding rate increased with increased BW and is related to the physical capacity for feed intake. Results indicate that pigs that ate faster also ate more (r = 0.29, P < 0.001), grew faster (r = 0.40, P < 0.001), and grew fatter (r = 0.28, P < 0.001), but had no greater or lower residual feed intake (r = -0.01). The linear regression slope of feeding rate on age seemed inherent to the individual and was correlated with feed intake but not with residual feed intake. Feeding length may be selected for in order to regulate absolute feed intake at different stages of growth.

Aging↗
PubMed1981

Role of water in regulating feed intake and feed efficiency of broilers.

Three trials were conducted to investigate the influence of restricting feed and water intake levels of a fast-growing selected broiler line to the same feed and water intake levels of a nonselected line and to investigate the relationship of water/feed ratios to feed conversion (feed/grain) ratios. The water intake of birds from the selected line on feed restriction was similar to that of birds from the selected line not on feed restriction from 1 to 14 days. However, restriction of water intake of selected line birds resulted in feed intake similar to that of nonselected line birds. From 1 to 14 days, feed conversions of the feed-restricted selected line birds were similar to those of the selected line birds not on feed restriction. Feed conversions of the water-restricted selected line birds were similar to those of nonselected line birds. The maximum deviation in water intake between the selected and nonselected lines was observed before the maximum deviation in feed intake between the two lines; and the maximum deviation in feed intake was observed before the maximum deviation in body weight. Data presented indicate that high water/feed ratios are associated with low feed/gain ratios.

Animal Feed↗
PubMed1987

Growth, feed efficiency and variation of individually fed Angus, polled Hereford and Holstein steers.

Individual growth and feed intake of 36 Angus, 27 Polled Hereford and 30 Holstein steers were determined from 365 to 560 kg live weight. One-half of the cattle in each breed were fed a diet based on high-moisture ear corn and the other one-half were fed a diet based on corn silage. Within each breed X diet group, half of the cattle were implanted with zeranol. Cattle fed the high-moisture ear corn diet were 8% more (P less than .01) efficient than cattle fed the corn silage diet. Cattle implanted with zeranol consumed 9% more (P less than .005) dry matter and gained 15% (P less than .005) faster, resulting in 5% (P less than .05) less dry matter per unit gain than unimplanted cattle. Holstein steers gained 11% faster (P less than .005) and consumed 8% less (P less than .025) dry matter per unit gain than the average of Angus and Polled Hereford steers. Within subclass coefficients of variation were 9.9, 14.3 and 13.7 for daily dry matter intake, average daily gain and dry matter per unit gain, respectively; within subclass correlations were .50 (P less than .01), .17 and -.75 (P less than .01) between daily dry matter intake and average daily gain, daily dry matter intake and dry matter per unit gain and average daily gain and dry matter per unit gain. When combined with previous data that show Holsteins attain the Choice grade with less trimmable fat and equal weight of trimmed primal cuts compared with traditional beef breeds of the same live weight, these results suggest that Holstein steers are under-valued feedlot beef cattle.

Animal Nutritional Physiological Phenomena↗
PubMed1988

Postweaning growth, feed efficiency and chemical composition of sheep as affected by prenatal and postnatal testosterone.

Data were collected from intact males, castrated males and ewe lambs to investigate the effect of presence or absence of testosterone prenatally and during the postweaning period on postweaning growth, feed intake and carcass chemical composition. Half the lambs from each sex were the progeny of dams that had received five injections of testosterone cyprionate from d 32 through d 87 of gestation. Linear contrasts were used to detect differences. Postweaning daily gain of intact males was greater (P less than .01) than that of male castrates. Ewe lambs from treated dams had approximately 12% greater rate of growth (P less than .04) than ewe lambs from control dams. Ewe lambs from dams that had been treated were 28% more efficient (P less than .01) in the conversion of food to weight than those from untreated dams. Ewe lambs from treated dams had heavier livers (P less than .07). Carcass protein for intact males was greater (P less than .11) than for castrates, and extractable fat was less (P less than .05). Masculinization of growth characteristics of ewe lambs affected the quantity of carcass fat relative to control ewes (7.59 vs 8.92 kg). These ewe lambs also had more water in the carcass than did the control ewes (13.93 vs 12.29 kg). Administration of exogenous testosterone to pregnant ewes over an interval of time approximating time of sexual differentiation in the fetus enhances postweaning growth rate, feed conversion efficiency and chemical composition of genetic females.

Animal Nutritional Physiological Phenomena↗
PubMed2003

Components of feed efficiency in broiler breeding stock: energetics, performance, carcass composition, metabolism, and body temperature.

Two experiments were conducted to identify factors influencing feed conversion in broilers. The first experiment was conducted to develop a test for body temperature (BT) under mild handling stress. In the first experiment, BT was recorded periodically with birds briefly restrained after they had been removed from feed with either continuous lighting or 16L:8D. Body temperature was affected by photoperiod and declined following feed removal. The second experiment was conducted to investigate metabolic-physiologic differences existing between good (G) and poor (P) converting broilers, initially classified in a commercial breeding company's feed conversion (FCR) test. Basal metabolic rate (BMR) and BT were measured at the beginning and end of the FCR test following appropriate time without feed. Heat production (HP) was recorded throughout the study both for BMR calculations and to measure net energy (NE). Excreta were collected for measurement of AME, and at study termination, birds were analyzed for carcass composition. The G and P converters, however, had similar BMR and feed consumption but differed in AME (58 kcal/kg) and total NE (184 kcal/kg). Generally, G and P broilers had similar starting BW, but the G broilers gained more weight on the same amount of feed than did P broilers. The two BT measurements recorded in the present study were correlated with each other. The BT was also correlated with subsequent gain and FCR, indicating potential use as an indicator trait for feed conversion. Further, the data indicated that processes other than basal metabolism (measured as average hourly HP) may impact FCR. These might include variability in fear response during BT measurement or variations in bird activity level.

Animal Nutritional Physiological Phenomena↗