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PubMed1985

Selection for weaning weight and postweaning gain in Hereford cattle. III. Correlated responses to selection in milk yield, preweaning and postweaning traits.

Single trait selection was practiced in three lines of Hereford cattle. Bulls were selected within sire families for increased weaning weight (WW) in the WW line (WWL), for postweaning gain (PG) in the PG line (PGL) and at random in the control line (CTL). Correlated responses to selection indicated that predicted milk yield in cows and preweaning daily gain and yearling weight in bulls and heifers were genetically improved in both WWL and PGL. Larger correlated responses were observed in PGL than in WWL. Birth weight in bulls and heifers increased in PGL but no genetic change was observed in WWL. Feed efficiency, feed intake and fatness were evaluated in bulls on postweaning feedlot test. No significant correlated responses in feed efficiency were observed in either line. Larger correlated responses in feed intake were observed in PGL bulls than in WWL bulls, while fatness was significantly increased in both selection lines.

Adipose Tissue↗

PubMed1996

Long-term selection for body weight in Japanese quail under different environments.

Long-term selection was conducted for high 4-wk BW in Japanese quail under different selection environments to investigate selection limits and to determine whether genetic parameters for growth are similar to those in chickens. Quail lines were selected under an adequate 28% CP diet (P line) and under a low 20% CP diet (T line). Mean realized heritabilities ranged from 0.32 (T line) to 0.49 (P line) during the first 10 generations. Although genetic variation remained following 97 generations of selection, realized heritabilities obtained agreed with theoretical predictions of loss of additive genetic variability with continuous selection. Similarity of heritability estimates indicates that Japanese quail are an excellent model for genetic studies of growth in meat-type chickens. Positive relationships accompanying selection for high 4-wk BW were increases in adult BW, age at first egg, and egg weight. Negative relationships were decreases in percentage fertility and hatchability, and egg production. Increased growth rate in selected lines was accompanied by an increase in feed and water intake, and by improvement in feed efficiency. Feed efficiency differences appeared to be important only immediately following hatch, whereas feed intake differences were present from 0 to 4 wk. Evidence of major physiological changes accompanying selection for growth were not observed. However, changes were observed in increased "resource allocations" to supply organs, during late embryonic stages and the 1st wk posthatch. Carcass composition was similar between unselected and selected lines except for higher fat and lower moisture levels in selected lines.

Animals↗

PubMed1993

Additive amelioration of tibial dyschondroplasia in broilers by supplemental calcium or feed deprivation.

Two experiments were conducted to determine the effects of mineral nutrition and early growth rate on tibial dyschondroplasia (TD) in broiler chickens. A corn-soybean meal diet with .6% available P (aP) was fed from the day of hatching for 20 days. Experiment 1 had a 2 x 2 x 2 factorial arrangement of treatments with two dietary levels of Ca (1.1 or 1.8% of the diet), two levels of dietary Cl (.22 or .34%), and two feeding systems (ad libitum or deprived of feed for 8 h three times per week on Monday, Wednesday, and Friday beginning at 6 days of age). Experiment 2 was a 3 x 2 factorial arrangement with three levels of Ca (1.14, 1.50, or 1.80%) and two feeding systems (ad libitum or deprivation as in Experiment 1). Nineteen-day BW gain was not affected by treatments in the first experiment. Feed deprivation decreased gain in the second experiment, and gain was increased by the highest Ca level without affecting feed efficiency. Feed deprivation did not affect feed efficiency in either experiment. Dietary Cl level did not affect any variable studied. Supplemental Ca increased bone ash in the first experiment, but not in Experiment 2. Feed deprivation and increasing Ca levels decreased the incidence of TD and the amount of severe lesions. Increasing dietary Ca resulted in a greater accumulation of Ca into the epiphyseal growth plate cartilage. The results suggest that the dietary Ca:aP ratio required for bone integrity in starter chicks may be greater than 2.2:1.

Animals↗

PubMed1982

Feed consumption and efficiency of feed utilization in chickens as affected by restriction of feed intake under subtropical conditions.

The influence of restricted feeding was investigated in 1145 Dandarawi (D) and 1092 Rhode Island Red (RIR) chickens and in 294 D and 211 RIR hens in their first laying year. The feed utilization during the rearing period (8 to 22 weeks of age) and the feed utilization for the egg production were not significantly affected by a reduction to 85 or 70% of the ad-libitum feeding ration during rearing and/or in the first laying year of both breeds. A feed restriction to 70% is recommended for D and to 85% for RIR chickens during the rearing period followed by ad-libitum feeding.

Aging↗

PubMed2001

Experience and social environment influence the ability of young brown trout to forage on live novel prey.

Efficient feeding is crucial for the growth, survival and reproductive success of most animals. In artificial-rearing environments, however, animals are deprived of many stimuli normally experienced in the wild, which may alter feeding behaviour, and thus influence their survival and reproductive success upon release in nature. In a laboratory experiment, we investigated the effect of hatchery rearing on the ability of brown trout, Salmo trutta, to capture and consume a novel live prey item. Hatchery-reared and wild-caught trout, originating from the same river, were fed single black crickets, either in isolation or in visual and olfactory contact with another hatchery-reared or wild-caught fish. Total consumption, time to first bite and feeding efficiency were monitored. Wild-caught trout ate more, were quicker to attack, and consumed attacked prey more efficiently than hatchery-reared fish. Food consumption and efficiency increased in both wild and hatchery-reared trout during the experiment. We propose that the differences in feeding ability between wild-caught and hatchery-reared brown trout were mainly due to differences in previous experience of feeding on live prey. Wild-caught trout tended to eat more and sooner when in visual contact with another fish than when in isolation. This trend was not seen for the hatchery-reared fish, which may be due to environmental differences between the hatchery and the natural stream. The initial inability of hatchery-reared fish to forage on live prey may reduce their success when released in the wild, especially when in competition with resident wild fish. Copyright 2001 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed2004

Selection for growth in brown trout increases feed intake capacity without affecting maintenance and growth requirements.

The correlated responses in feed intake and G:F ratio with selection for increased growth rate were evaluated by comparing selected (S) and control (C) brown trout (Salmo trutta) reared under conditions known to affect feed efficiency: feed restriction and periods of compensatory growth. Nitrogen and energy requirements for maintenance and growth were also measured. Trout were allotted at comparable BW (3.7+/-0.06 and 3.8+/-0.04 g, for C and S respectively) to triplicate groups per treatment. The experiment lasted a total of 198 d, during which animals were successively submitted to a 116-d feeding phase and fed 10, 30, 50, 70, 100, and 140% of their usual daily ration (UDR), a 35-d phase of food deprivation, and a 47-d refeeding phase. The G:F of C and S were comparable in all experimental conditions tested. During the feeding phase, S grew better than C only when fed 100 and 140% UDR (P < 0.001). This was explained by a higher feed intake capacity. The requirements for growth and maintenance were similar among the lines, which is in agreement with their comparable loss of weight (mean energy loss of -53 and -55 kJ/(kg x d) for C and S, respectively; P > 0.38) observed during the feed deprivation phase and the lack of differences in carcass composition (fat, P > 0.35; protein, P > 0.54). During the refeeding phase, growth performance and G:F were high in all groups. The daily growth coefficient was higher in S than in C (P < 0.001) because of a higher feed intake (P < 0.001). An increase in absolute individual variability in final BW and length was associated with the level of food restriction in both lines; however, it always remained lower in S than in C. In conclusion, fish selected for growth under ad libitum conditions will only exhibit growth superiority when fed diets close to ad libitum, and there was no evidence that selection was associated with an improvement in efficiency of maintenance nor in retention of body tissues.

Animal Feed↗

PubMed2003

The effect of chronic feeding of diacetoxyscirpenol and T-2 toxin on performance, health, small intestinal physiology and antibody production in turkey poults.

1. The effects of feeding T-2 toxin or diacetoxyscirpenol (DAS) at levels up to 1 ppm for 32 d on performance, health, small intestinal physiology and immune response to enteral and parenteral immunisation were examined in young poults. 2. Slight improvement in growth was observed in some groups of poults fed T-2 or DAS mycotoxins for 32 d, with no change in feed efficiency. Feeding both T-2 and DAS resulted in oral lesions which had maximal severity after 7-15 d. 3. Mild intestinal changes were observed at 32 d but no pathological or histopathological lesions were found. Both mycotoxins altered small intestinal morphology, especially in the jejunum where villi were shorter and thinner. In addition, both DAS and T-2 mycotoxins enhanced the proportion of proliferating cells both in the crypts and along the villi. Migration rates were reduced in the jejunum of poults fed T-2 toxin but did not change in the duodenum or in poults fed DAS. 4. No significant effects of T-2 or DAS were observed on antibody production to antigens administered by enteral or parenteral routes. 5. This study indicates that tricothecene toxins at concentrations of up to 1 ppm for more than 30 d influenced small intestinal morphology but did not affect growth or antibody production.

Administration, Oral↗

PubMed1998

Soybeans transformed with a fungal phytase gene improve phosphorus availability for broilers.

Male broilers (n = 416) were used to compare the efficacy of providing dietary phytase either as a commercial supplement or as a recombinant protein in transformed soybean. From 7 to 21 d of age, broilers were fed a basal diet containing 0.20% nonphytate P (nP) with additional supplementation by fungal phytase as Natuphos or as raw transformed soybeans expressing recombinant phytase at 400, 800, or 1,200 U/kg. For comparison, broilers were also fed the basal diet containing 0.08, 0.16, or 0.24 added nP. The basal diet was fed as the negative control. Diets were consumed ad libitum as a mash. All excreta were collected from each pen from 18 through 20 d of age, and the birds were killed at 21 d of age. Supplementing the basal diet with nP linearly increased body weight gain, feed efficiency, feed intake, toe ash weight and percentage, and tibia shear force and energy. Phosphorus digestibility decreased linearly as nP level increased, but P excretion increased. Dietary phytase linearly increased growth rate, feed intake, toe ash weight and percentage, tibia shear force and energy, and P digestibility, whereas excretion was decreased. Except for P digestibility, there was no difference in efficacy of responses for performance, bone mineralization, and P excretion between the two sources of phytase. It appears from this study that phytase can improve growth performance of broilers fed low nP diets when provided either as a commercial supplement or in the form of transformed seeds.

6-Phytase↗

PubMed1985

Dietary protein and yolk sac inoculation with Escherichia coli in young turkeys.

An experiment was conducted to examine the effect of pathogenic Escherichia coli inoculated into the yolk sac of day-old turkeys. Escherichia coli was isolated from the yolk sac of stunted poults and inoculated directly into the yolk sac of day-old birds. Poults were administered either .1 ml of uninoculated sterile Todd-Hewitt broth or .1 ml of a 10(-3) or 10(-2) dilution of a 24-hr E. coli culture containing 3.4 X 10(8) viable bacteria/ml. In addition, poults were fed either 28 or 22% protein diets from 0 to 21 days of age to form a 3 X 2 factorial arrangement. Body weight gain and feed consumption were measured weekly, and dry matter and protein retention and nitrogen-corrected metabolizable energy were measured from 7 to 10 and 17 to 20 days postinoculation. Intestinal mucosal dipeptidase and maltase activities were determined at 21 days of age. Average mortality by 7 days of age was increased from 1 to 36% from the E. coli inoculation of the yolk sac. Escherichia coli significantly depressed body weight gain and feed consumption 27 and 30, 13 and 16, and 6 and 8%, respectively, during the first, second, and third weeks of the experiment but failed to affect feed efficiency. Feeding a 28% protein diet alleviated the depression in feed consumption and body weight gain to some extent compared with a substantial depression at 22% protein. Nitrogen content and gross energy of the excreta were increased by both dilutions of E. coli for the 7 to 10-day period; this was indicative of a malabsorption of nutrients.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Effect of varying levels of phosphorus and live yeast culture in caged layer diets.

Dietary levels of .31, .36, .41, .46, .51, .56, and .61% total phosphorus (TP) were incorporated into seven corn-soy diets to determine the minimum TP requirement of caged laying hens. Each diet was fed to six lots of 20 hens each for a test period of 308 days. Egg production, feed efficiency, feed consumption, egg weight, and egg breaking strength were the performance criteria. Egg breaking strength was significantly higher while the other performance measures were significantly inferior for hens receiving the .31 TP diet as compared to those hens receiving the other diets. Performance measures of hens receiving diets with TP levels ranging from .41 to .61% were not significantly different. Although hens receiving the .36% TP diet performed significantly better than those receiving diets containing .31% TP, their performance was not satisfactory when compared with performance of hens fed diets containing higher levels of phosphorus. In a second experiment, dietary levels of 0, .25, and .50% live yeast culture (LYC) were fed in combination with TP levels of .40 and .60% to individually caged hens for nine test periods of 28 days each. Each of the test diets was fed to three lots of 12 hens each. Performance criteria in this experiment were the same as those used in the first experiment. Hen responses to the six test diets did not differ significantly for any performance criterion, except for egg breaking strength, which was significantly higher for eggs produced by hens fed diets containing .40% TP level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Lack of effect of dietary factors on nicarbazin toxicity in broiler chicks.

Effects of dietary fat, protein, and methionine levels and the type of dietary grain in nicarbazin-containing diets on the growth response of broiler chicks were evaluated in five experiments in a factorial design. Nicarbazin at levels ranging from 100 to 200 mg/kg significantly (P less than .05) depressed weight gain and feed efficiency. Feed intake was significantly reduced only when nicarbazin was used at levels of 150 and 200 mg/kg. The latter concentration also significantly decreased water intake and water:feed ratio. Nicarbazin, at a level of 150 mg/kg, did not affect dietary metabolizable energy content or the retention of nitrogen and dry matter. A higher level of soybean oil (3.5 vs. .5 or 1.0%) did not counteract the growth-depressing effects of 100, 150, and 200 mg nicarbazin/kg. The growth-depressing effect of the highest dose also was not affected by increasing the protein level from 18.2 to 20.4%. Neither type of dietary grains (corn vs. sorghum) nor supplemental methionine level affected the toxicity of 125 mg nicarbazin/kg. Water intake and water:feed ratio were significantly increased due to elevation of dietary protein and fat levels. It was concluded that the severity of the growth-depressing effect of nicarbazin on chicks was not dependent on the levels of dietary unsaturated fat, protein, and methionine.

Animals↗

PubMed2003

Toxicity of Senecio vernalis to laying hens and evaluation of residues in eggs.

Diets with 0.0, 0.5,2.0, or 4.0% ground-aerIal parts of Senecio vernalis were fed to groups of 10 laying hens for 210 d. Plant alkaloid content was 0.14% with 8.57% in the basic form and 91.43% in the N-oxide form. Specific alkaloids were senecionin (66.65%), senecivernin (10.37%), seneciphylline (8.51%), integerrimine (8.44%), retrorsine (3.03%), senkirkine (2.35%) and hydroxysenkirkine (0.65%). At the end of the feeding period, no mortality or clinical signs occurred in any test group. However, decreases in egg production, feed efficiency, feed intake and body weight occurred on diets containing 2 or 4% of the plant. Serum gamma-GT was significantly elevated and serum albumin and protein were significantly decreased in hens fed the 2 and 4% diets. Total bilirubin was significantly higher in the 4% group. No free pyrrolizidine alkaloids were detected in eggs indicating that at these rates of dietary exposure, they did not produce residues at the level of detection or that they were bound irreversibly to egg proteins. Hens fed 2 or 4% plant diets had mild to moderate chronic liver changes of periportal or septal fibrosis, megalocytosis, bile duct hyperplasia and early regenerative nodule formation.

Animal Feed↗

PubMed1980

The effects of different protein and energy levels and time of change from starter to finisher ration on the performance of broiler chickens in the tropics.

Three experiments were conducted to determine the optimum protein and energy levels for starting and finishing broiler chickens and the optimum time of change from broiler starter rations to broiler chicken finisher rations. We tested four protein levels (17, 20, 23, and 26%), each fed at three energy levels (2800, 3000, and 3200 kcal/kg diet). For starting chickens, maximum weight gains, feed efficiency, and lowest feed cost per kilogram live weight gain were obtained on the rations containing 23 or 26% protein. Differences in dietary energy levels did not significantly affect weight gain and feed consumption. Feed efficiency improved with increase in dietary energy levels although the differences in feed efficiency between any two consecutive groups were not significant. Feed cost tended to increase nonsignificantly with increase in energy level. For finishing broiler chickens, dietary protein level did not have any significant effects on weight gains. The poorest weight gain, feed efficiency, and feed cost per kilogram gain were obtained on the rations containing 17% protein. The differences in feed efficiency between protein levels of 20, 23, and 26% were not significant while no two consecutive protein levels among the 20, 23, and 26% protein diets gave feed cost per kilogram gain that was significantly different from each other. Weight gain, feed consumption, and feed cost per kilogram gain were not significantly affected by dietary energy levels. Efficiency of feed conversion tended to improve with increase in dietary energy levels, although differences in feed efficiency between 3000 and 3200 kcal/kg diet were not significant. Performances of birds fed the starter ration for 0, 1, 2, 3, or 4 weeks before changing to the finisher ration were not as good as those fed the starter ration for 5 or 6 weeks before being change) to the finisher ration or those fed the starter ration for the 9 weeks experimental period. The results of the present work indicate that a protein level of 23% and energy level of 2800 to 3000 kcal/kg diet may be recommended for starting broiler chicks raised in Nigeria. For finishing broiler chickens, a protein level of 20% and energy level of 3000 kcal/kg diet may be recommended. The optimum time of change from broiler starter to broiler finisher may be recommended at 5 or 6 weeks of age.

Animal Nutritional Physiological Phenomena↗

PubMed1989

The utilization of nitrogen for growth in mice fed blends of purified proteins.

Reasons for differences in growth of weanling mice fed different blends of purified proteins in diets apparently adequate in indispensable amino acids were investigated. Dietary nitrogen provided at increasing levels from a mixture of casein, gelatin, and zein, or from these plus gliadin and lactalbumin resulted in similar weight gains and efficiency of feed utilization in weanling mice. These responses were always lower (P less than 0.05) than for mice fed the control diet. When diets were based on true digestible nitrogen and amino acids, weight gains and feed efficiency decreased (P less than 0.05) as the dietary nitrogen level increased. High plasma glycine concentrations and high phenylalanine to tyrosine ratios were associated with high dietary glycine levels provided by gelatin. When a mixture of constant proportions of protein sources, predominantly casein, supplied most of the dietary nitrogen, small increases in weight gains and feed efficiency were observed as the nitrogen level in the diet increased. Varying the proportions of sources, which increased the percentage of gelatin, resulted in decreased gains in response to more dietary nitrogen. Replacing the amino acids found in gelatin by crystalline L-amino acids and replacing glycine by glutamic acid improved gains and feed efficiency (P less than 0.05) compared with gelatin-containing diets. These studies demonstrated that glycine at dietary concentrations of approximately 1-2%, either from gelatin or as the free amino acid, inhibited growth and feed utilization of growing mice.

Amino Acids↗

PubMed1989

Severe feed restriction in pullets during the early growing period: performance and relationships among age, body weight, and egg weight at the onset of production.

The performance of egg type (Leghorn x Rhode Island Red) chickens that were feed restricted during the prelaying period was studied in two trials, each conducted with 300 hens. In Trial 1, treatments included 1) an ad libitum-fed control; 2) restriction for close to zero growth between 7 and 28 days of age; 3) the same restriction as (2) but continued by restriction of 50% growth up to 70 days; 4) restriction between 7 and 70 days for 50% growth; and 5) restriction for 50% growth between 7 and 98 days. In Trial 2, birds were restricted severely (close to zero growth) from 7 to 28 days of age, followed by restriction of 50% growth up to 28, 56, 84, and 112 days of age, respectively. In all cases, feed restriction resulted in a delay in the onset of egg production, leading to some increases in egg weight. Egg production rate and cumulative production were not affected, in most cases, by early feed restriction. The BW at the onset and after 20 mo of production was reduced when feed restriction was continued beyond the age of 84 days. Overall feed conversion (grams feed per egg) and feed efficiency (grams feed per gram egg mass) were not affected significantly by feed restriction, although feed efficiency (grams gain per gram feed) was improved during the prelaying period. Within each treatment, BW was positively correlated with age at onset of egg production. Egg weight was a function of both age and BW at the onset of production. The significant correlation between egg weight and BW was maintained even after a year of production.

Age Factors↗

PubMed1979

Studies on duck nutrition. III. Arginine and lysine requirements of mule ducklings.

Growth assays were conducted to determine the dietary arginine and lysine requirements of mule ducklings. The metabolizable energy content of the basal diets used for the arginine and lysine requirement studies was 2810 and 2828 kcal/kg, respectively. Two-day-old ducklings of mixed sexes were fed on a starter diet for one week, fasted for 8 to 12 hr and then were fed on experimental diets for 12 or 14 days. Weight gain and feed consumption were recorded at the end of each experiment. The minimum requirements for arginine and lysine were obtained by regression analysis of weight gain or feed efficiency against arginine or lysine content in the diet. The minimum arginine requirements for maximum growth and efficiency of feed utilization were 1.08% of the diet or 6.0% of the dietary crude protein. The minimum requirements of the total lysine and available lysine were 1.06% and .97%, respectively, of the diet or 5.9% and 5.4%, respectively, of the dietary crude protein for both maximum growth and feed efficiency.

Animal Feed↗

PubMed1997

The response of broiler chickens and turkey poults to steam-pelleted diets supplemented with fat or carbohydrates.

The responses of growth and feed efficiency to pelleted feed was investigated in 4- to 7-wk-old broiler chickens, and in 8- to 12- and 16- to 20-wk-old turkeys. In all cases, the growth and feed efficiency responses were linear within the ranges of dietary energy tested. When energy was added by carbohydrate supplementation, weight gain and feed efficiency responses were parallel for both mash and pellets, but due to the growth response to pellets, the elevation was higher for pellets than for mash. When energy was added by fat, the growth response to pellets also resulted in an increase in function elevation but the slope of the response was lower than in mash feeding, possibly due to a decline in pellet quality as dietary fat increased. Grinding of pellets completely abolished the growth and feed efficiency responses observed when the physical form was preserved. In chickens, comparisons of ground pellets to mash suggested some decline in nutritional quality due to the process of pelleting when either carbohydrates or fat were increased in the diets. In both chickens and turkeys, the feeding of pelleted diets resulted in an increase in abdominal fat.

Animal Feed↗

PubMed1998

Effects of programming intake on performance and carcass characteristics of feedlot cattle.

We conducted two experiments to determine the effects of various intake restriction strategies on performance and carcass characteristics of feedlot cattle. In Exp. 1, 104 steer calves (273 +/- 12 kg BW) were allotted to 12 pens. During Period 1 (273 to 372 kg BW), steers were limit-fed according to net energy equations to achieve predicted gains of .91, 1.13, or 1.36 kg/d. Control steers were offered ad libitum access to feed during this period. During Period 2 (372 to 535 kg BW), all steers were offered ad libitum access to feed. In Period 1, steers limit-fed for predicted gains of .91, 1.13, and 1.36 kg/d gained 1.03, 1.22, and 1.40 kg/d, respectively. Control steers offered ad libitum access to feed gained 1.66 kg/d. Steers that were limit-fed in Period 1 were able to compensate in Period 2; for the total experiment, there were no differences (P > .10) among the four feeding strategies investigated for rate of gain, feed efficiency, total feed intake, and carcass characteristics. Experiment 2 used 107 steer calves (300 +/- 11 kg BW). Four feeding strategies were compared: step-wise increases in intake to program for increasing rate of gain, stepwise decreases in intake to program for decreasing rate of gain, feeding to hold gain constant at 1.36 kg/d, or offering steers ad libitum access to feed throughout the experiment to allow for maximum gains. When averaged over the total experiment, growth rate and days on feed were not affected (P > .10) by feeding system. Steers fed to achieve a step-wise increase in growth rate throughout the experiment had the lowest (P < .09) daily intakes and the highest (P < .09) feed efficiencies. Steers fed for increasing gains required 109 kg/steer less (P < .09) total feed to reach market weight than those offered ad libitum access to feed throughout the experiment. Feeding strategy had little effect on carcass characteristics. We concluded that as intake is restricted to a greater extent, net energy equations are less accurate in predicting rate of gain. Programming intake during the feeding period can result in significant reductions in feed expenditures.

Animal Feed↗