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PubMed2001

Deep-stacked broiler litter as a protein supplement for dairy replacement heifers.

Fifty Holstein dairy heifers, [two replications of 25 heifers; average body weight (BW) 227 kg], were assigned to one of the following treatments for 105 d. Treatments 1 through 4 are given as the percentage of supplemental crude protein (CP) from soybean meal and deep-stacked broiler litter, respectively: 1) 100 and 0%; 2) 67 and 33%; 3) 33 and 67%; 4) 0 and 100%; and 5) 67% of supplementary CP from deep-stacked broiler litter and 33% from a source of rumen undegradable protein (RUP). All rations were formulated to contain 15% CP and 68% TDN on a dry matter basis. Dry matter intake was not significantly different among treatments at 10.1, 10.2, 10.4, 9.4, and 9.1 kg/d for treatments 1 through 5, respectively. Average daily BW gains (1.35, 1.37, 1.28, 1.17, and 1.24 kg/d for treatments 1 through 5, respectively) decreased linearly as the level of litter feeding increased and was not influenced by increasing RUP in treatment 5. Feed efficiency was not affected by the level of deep-stacked broiler litter feeding. Ruminal ammonia and plasma urea nitrogen concentrations decreased linearly as the level of litter feeding increased. Feeding additional RUP decreased ruminal ammonia concentration in treatment 5 to a level similar to treatment 4. This suggests that the protein in deep-stacked broiler litter may be more undegradable than that in soybean meal and that RUP in broiler litter may be higher than previously thought. Results from this study indicate that deep-stacked broiler litter has potential as a low-cost CP source for growing dairy heifers.

Ammonia↗

PubMed1985

Influence of virginiamycin on energy utilization when turkey poults were fed ad libitum or restricted.

An experiment was conducted with day-old turkey poults to study the influence of virginiamycin on energy utilization. A 2 X 2 factorial arrangement of treatments was used, which included ad libitum or a 25% feed restriction and 0 or 22 ppm of virginiamycin. Virginiamycin in the diet significantly improved body weight, feed efficiency, and dietary energy utilization when poults were fed ad libitum or when feed was restricted. These data indicate that virginiamycin enhances the utilization of dietary energy by turkey poults.

Animals↗

PubMed1988

Growth performance and carcass composition of turkey hens fed corn gluten feed.

Female poults were fed diets containing 0, 10, or 20% corn gluten feed (CGF) from 0 to 16 wk of age or no CGF from 0 to 9 wk and 20% CGF from 9 to 16 wk of age. All diets were formulated to be isonitrogenous and isocaloric, within each age interval. Diets containing CGF had no significant effect on body weight gain, feed efficiency, yield of carcass parts, or carcass composition, as compared with effects of feeding a corn-soybean meal control diet. However, age of slaughter, 14 vs. 16 wk, had a significant effect on the proportion of breast meat, breast bone, thigh skin, thigh bone, and drums. Carcasses were significantly higher in protein and lower in fat at 14 wk than at 16 wk of age. Results suggest CGF can successfully constitute up to 10% of the diet of growing turkey hens. The use of CGF in turkey diets up to this level would be governed by the economics of the nutrient supply. At 20% of the diet, the tendency for CGF to induce moist droppings may impose a restriction on its use, and the degree of restriction would depend on the housing-management situation.

Animal Feed↗

PubMed1995

The effects of continuously or diurnally fed melatonin on broiler performance and health.

An experiment was designed to investigate the effects of dietary melatonin (MEL) on the performance and health of broiler chicks. Chicks raised under constant lighting were fed practical broiler diets in mash form containing 0, 20, or 40 ppm MEL from 0 to 3 wk. A fourth treatment (0 ppm MEL: 6h/d; 20 ppm MEL: 18 h/d) was used to mimic a diurnal light:dark cycle. Commercial broiler grower diets without MEL supplementation were fed from 3 to 6 wk of age. A small dose-related decrease was observed in weight gain (0 to 14 d) and feed consumption (0 to 21 d) due to continuous feeding of MEL. Continuously fed MEL also improved feed efficiency in the first 3 wk vs the control (0 ppm). Growth and feed consumption from 0 to 21 d were not affected by the diurnally fed diet when compared with the control treatment. No effects were found for mortality. However, the incidence of sudden death syndrome (SDS) was numerically less for the diurnal (3.56%) and 40 ppm (3.76%) diets from 0 to 42 d than for the control treatment 5.56%. Skeletal disease was generally unaffected, with the exception of the incidence of crooked toes at 42 d (0 ppm MEL: 8.67% vs diurnal: 4.89%). Dietary MEL fed either continuously or in a diurnal pattern had a minor effect on the performance and health of broiler chickens.

Animals↗

PubMed2003

Intoxication of Crotalaria pallida seeds to growing broiler chicks.

The adverse effects of feeding Crotalaria pallida (CP) seeds to chicks was investigated in a 21-day randomized trial of 4 dietary treatments (control, 1,2 and 3% ground CP seeds). Mortality rates in birds fed 0, 1, 2, and 3% dietary CP were 0, 2.1, 6.2, and 16.7%, respectively. Body weight gain and feed efficiency were adversely affected by all levels of inclusion of CP seeds, but feed intake was decreased only by dietary levels of 2 and 3%. Dietary CP of 2 and 3% increased the relative weight of lung, heart and spleen. Relative liver weight was increased by 2% dietary CP, but decreased by 3% CP. At day 14, serum GGT was increased by 2 and 3% dietary CP; serum ALT was significantly increased by 3% CP. No differences in ALT, AST or GGT were observed at day 21. Dietary levels equal to or greater than 1% CP are toxic for growing broiler chicks.

Alanine Transaminase↗

PubMed2001

Immunostimulatory effects of anionic alkali mineral complex solution Barodon in porcine lymphocytes.

The anionic alkali mineral complex solution, Barodon (Barodon-S.F. Corp., Korea), was evaluated for its effectiveness as a nonspecific immunostimulator in pigs. The effects of Barodon were determined by analysis of feed efficiency, growth rate, and phenotype of leukocyte subpopulations using monoclonal antibodies specific to porcine leukocyte differentiation antigens and flow cytometry (FC). The study was focused to investigate the change in proportion of the CD4+CD8+ double positive T lymphocyte subpopulation (dpp) which exists uniquely in pigs. In addition, the mitogen-stimulated lymphoproliferative response, tissue distribution in lymphoid organs and the adjuvant effect of Barodon on hog cholera vaccine efficiency were determined. The study has revealed the average daily gain rates and feed conversion rates were significantly (p<0.05) improved in either group of pigs fed with 0.05% Barodon-spray feed (Tx-1) or pigs fed with 3% Barodon-fermented feed (Tx-2) in comparison with group of pigs fed with feed containing no Barodon (control). The proportion of cells expressing CD4+ antigen in Barodon-treated group increased from 3 weeks posttreatment and was significantly higher (p<0.05) than that of control at 8 weeks posttreatment. Particularly, the significantly higher proportion was maintained from 8 weeks through 13 weeks posttreatment in Tx-1 group (p<0.05). The proportion of cells expressing CD8+ antigen was significantly higher at 3 weeks posttreatment in Tx-2 (p<0.01). Proportion of MHC class II-expressing cells was significantly higher in Tx-1 and Tx-2 group at 11 weeks and 8 weeks posttreatment (p<0.05), respectively. In addition, the proportion of Non T/Non B (N) cells was also significantly higher in Tx-2 at 3 weeks posttreatment (p<0.01) and maintained to 13 weeks posttreatment (p<0.1). Between Barodon-treated groups, the proportion of MHC class II-expressing cells was observed to be larger in Tx-2 than Tx-1 from 3 weeks to 8 weeks posttreatment (p<0.05). However, there were no significant difference in the proportions of CD2+ cells, B cells, monocytes and granulocytes between Barodon-treated and control group during the experiment. Dual-color FC analysis, study has revealed an increased proportion of dpp present in lymphocytes obtained from peripheral blood (PB) and mesenteric lymph node (MLN) of Barodon-treated group at 8 and 11 weeks posttreatment. The proportion of dpp in PB was 27.5% and 32.1% in Tx-1 and Tx-2, respectively, but only 2.2% in control group at 8 weeks posttreatment. In MLN, the proportion was 45.1% and 52.1% in Tx-1 and Tx-2, respectively, otherwise 16.5% in control group at 8 weeks posttreatment. The mitogen-stimulated activity was significantly higher in Tx-1 than in the control group at 11 weeks posttreatment when cells were stimulated with Con A and PHA, respectively (p<0.01). Also, Con A-, PHA and PWM-stimulated activity was significantly higher in Tx-2 than in the control group at the same time (p<0.05). The tissue distribution of CD4+, CD8+ and CD4+CD8+ dpp in MLN and spleen was significantly larger in Tx-1 and Tx-2 than in the control group (p<0.01). Also, a larger proportion of dpp was observed in Tx-2 than Tx-1 in spleen between Barodon-treated groups (p<0.01). In conclusion, the study has demonstrated that Barodon had an immunostimulatory effect on pigs through proliferation and activation of porcine immune cells, specially CD4+CD8+ dpp lymphocytes.

Adjuvants, Immunologic↗

PubMed2003

Impact of energy intake and pregnancy status on rate and efficiency of gain and backfat changes of sows postweaning.

A collaborative study was conducted to evaluate factors related to determining optimal feeding and management programs for increasing net returns from marketing cull sows. A total of 269 multiparous sows averaging 192 kg of body weight were weaned, moved to individual gestation crates, and assigned to one of eight treatment combinations in a 2 x 2 x 2 factorial arrangement for a 42-d postweaning feeding experiment. Factors included limited (L) (1.8 kg/sow/d) or ad libitum (AL) access to feed during wk 1 postweaning, a corn-soybean meal (corn) or barley-sunflower meal (barley) diet, and pregnant or nonpregnant status. All sows were provided ad libitum access to feed from wk 2 to 6 postweaning. Gain and feed intake (FI) data were collected weekly for each sow and used to calculate gain:feed (G/F). Ultrasonic backfat (BF) data were collected on d 0, 21, and 42 postweaning. Sows on the AL treatment had greater FI (P < 0.05) but similar gain (P = 0.80) for the 42-d postweaning period compared to sows on the L treatment. Most of this response was due to lower sow body weight loss during wk 1 postweaning (P < 0.01) when sows were provided AL (-7.2 kg) vs L (-13.2 kg) access to feed. Sows fed the corn diet had higher gain (P < 0.01), improved G/F (P < 0.01), and increased BF (P < 0.01) over the 42-d feeding period than sows fed barley. The corn diet resulted in less sow BW loss (P < 0.01) during wk 1 (-8.8 kg) than the barley diet (-11.6 kg). Pregnant sows had higher gain, FI, G/ F, and BF (P < 0.01) than nonpregnant sows over the 42-d feeding period. Most of this advantage occurred during wk 4 postweaning when FI and gain of nonpregnant sows was lower (P < 0.01) than for pregnant sows. An economic analysis indicated that, when cull sow prices are relatively high and feed prices are moderate to low, maintaining and managing cull sows for an additional 6 wk postweaning may be economically advantageous compared to 0 or 3 wk. Pregnant sows fed the corn diet produced the greatest economic return. These results suggest that mating sows as they return to estrus postweaning and providing ad libitum access to a corn-soybean meal diet improves growth performance and feed efficiency, and may thereby provide increased returns when marketing cull sows.

Adipose Tissue↗

PubMed1997

Energy concentration of high-oil corn varieties for pigs.

Growth performance and utilization of nutrients and energy in three high-oil corn varieties (5.4 to 9.7% ether extract) and regular corn (4.2% ether extract) were compared in three experiments using growing pigs. Twenty-four 25-kg crossbred barrows were used in Exp. 1 to evaluate nutrient and energy digestibility in the three high-oil corn varieties and regular corn. Four diets were formulated to contain 97% of one of four varieties of corn (Control, TC1, TC2, and X122 varieties) and 3% minerals and vitamins. Digestibilities of nitrogen and ether extract were similar (P > .05) for regular corn and all three varieties of high-oil corn. The digestible energy concentrations (kcal/g; as-fed basis) for control, TC1, TC2, and X122 corn varieties were 3.29, 3.57, 3.4, and 3.41, respectively, with control lower (P < .05) than TC2 or X122 and TC1 higher (P < .05) than TC2 or X122. Metabolizable energy concentrations averaged 98.4% of digestible energy concentrations. In Exp. 2, four diets formulated to contain 79% of one of the four corn varieties, 18.25% 48% CP soybean meal, 2.45% vitamins and minerals, and .3% lysine.HCl were fed to 24 crossbred barrows (six pigs per diet) in a nutrient and energy balance study similar to the Exp. 1. Results were similar to those obtained in Exp. 1. The same four diets that were used in Exp. 2 were fed to 40 (10/diet) 20-kg crossbred pigs (20 barrows and 20 gilts) in a 28-d growth performance study (Exp. 3). Gain:feed ratios were .39, .43, .42, and .42 and growth rates (kg/d) were .68, .74, .70, and .72 for diets containing control, TC1, TC2, and X122 corn varieties, respectively. These translate to 8 to 10% improvement in feed efficiency and a numerical improvement in weight gain (3 to 9%) when high-oil corn was fed as compared with control corn. The results of nitrogen, ether extract, and energy balance and feeding experiments with growing pigs indicate efficient utilization of nutrients in diets containing high-oil corn.

Animals↗

PubMed1997

Nutritional efficacy of a spermidine supplemented diet.

Polyamines (PA) are ubiquitous cell components essential for growth. Dietary PAs are directed preferentially to tissues and organs that have been stimulated to grow by metabolic signals. Nutritional efficacy and growth potential of an oral PA supplement, spermidine (SD), was examined in growing rats. A group of 24-male Sprague-Dawley rats (200-220 g) was adapted to our vivarium conditions for 3 d, then fed ad libitum continuously for 14 d. During feeding they received either a basal diet (n = 8) or a test diet containing the basal diet with 0.05% SD (test diet 1, n = 8) or 0.10% SD (test diet 2, n = 8). This dose of SD corresponds to an intake of 54 and 108 mumol of SD per rat per day. At the end of 14 d of feeding, the animals were sacrificed and plasma, cerebral spinal fluid (CSF) and tissues (muscle, brain, and liver) were harvested for amino acid analysis. Voluntary food intake, body weight gain, and nitrogen excretion and balance were significantly decreased in test diet 2 fed rats compared to test diet 1. The opposing trends in the accumulation/depletion of free amino acids (AA) in muscle and plasma suggests that the exogenous supply of SD blocks the transport of amino acids, as well as PAs from the cells, since AA and PA share the same transport systems. A trend toward decreased weight gain and feeding efficiency was observed when high concentrations of SD were fed. It was concluded that feeding of SD at moderate intake is not toxic and does not retard growth. Oral administration of a smaller dose (<0.05%) of SD may promote further growth. The optimal level of SD dietary supplementation has thus yet to be established.

Amino Acids↗

PubMed2001

Early age thermal conditioning and a dual feeding program for male broilers challenged by heat stress.

The effects of early age thermal conditioning (TC) and dual feeding on responses of male broilers to a thermal challenge at 34 d of age are reported. Three hundred chicks were randomly divided into two equal groups. One group was exposed to thermal conditioning (38 C, 42% relative humidity for 24 h) at the age of 5 d, and the other group was not exposed. From 11 to 41 d of age, temperature was diurnally cyclic: 26 C (1600 to 0900 h) and 30 C (0900 to 1600 h). From Day 19, a factorial (2 x 2, TC x diet) experiment was conducted using eight pens of six broilers per treatment. Diets were control diet and dual feeding of a high protein fraction (1600 to 0900 h) and an energy-rich fraction (0900 to 1600 h). Growth and feed efficiency were slightly enhanced (+4%) by thermal conditioning and slightly reduced (-4%) by dual feeding. Mortality during thermal challenge was reduced by both factors. [In not conditioned chicks (N), 31 fed a control grower diet (NG) and 12 on a dual feeding program (NDF) died; in thermal conditioned chicks (T), 18 fed a control grower diet (TG) and 11 on a dual feeding program (TDF) died.] Before the thermal challenge period, body temperature (Tb) was consistently reduced in T. During the thermal challenge period, Tb was reduced by thermal conditioning and dual feeding. Measured at the age of 32 d, Tb gave an estimation of the ability of the chickens to cope with heat stress 2 d later. Pectoral mass was increased in TG, whereas the liver and the gizzard were significantly heavier in TDF and NDF. These results suggest that thermal conditioning at 5 d of age induces a consistent metabolic change in broiler males. The dual feeding program might have induced transitory effects on heat production during the heat stress.

Adaptation, Physiological↗

PubMed1998

Vitamin E reduces glucocorticoid-induced growth inhibition and lipid peroxidation in rats.

This experiment was conducted to study the effects of vitamin E on growth inhibition and lipid peroxidation in rats treated with different levels of corticosterone (CTC). Rats (Sprague-Dawley strain, 5 weeks of age) were divided into two groups: control group receiving a basal diet containing 60 mg DL-alpha-tocopheryl acetate/kg diet, and vitamin E group receiving the same diet supplemented with 5,000 mg tocopherol. After 6 days, rats of both diet groups were further divided into three groups by dose levels of CTC treatment (0, 25, and 100 mg CTC/kg body weight/d). CTC was administered to the rats by subcutaneous injection for 4 d. Growth was dose-dependently inhibited by the CTC treatment. Feeding the vitamin E diet significantly (p < 0.05) improved growth retardation. Feed efficiency was lowered by CTC treatment, while this was significantly (p < 0.05) minimized by feeding the vitamin E diet. Lipid peroxidation (TBARS) in the liver was elevated by the CTC treatment (p < 0.001) when the rats were fed the basal diet. The increment in TBARS was significantly (p < 0.001) reduced by vitamin E. The activities of glutathione S-transferase (GST) and superoxide dismutase (SOD) were significantly reduced by the CTC treatment in a dose-dependent manner in both dietary groups. Feeding vitamin E significantly (p < 0.001) improved the reduction in GST activity. The SOD activity showed some tendency. The present results demonstrate the effectiveness of vitamin E in improving growth retardation in glucocorticoid-treated rats and suggest that reductions in increased lipid peroxidation due to CTC may be an important factor of the action of vitamin E.

Animals↗

PubMed1984

Phenotypic profiles of broiler stocks fed two levels of methionine and lysine.

A phenotypic profile was compiled for eight commercial broiler stocks fed diets containing two levels of methionine and lysine. Stock by diet interactions were unimportant for most traits, although differences among stocks were somewhat magnified when they were fed the lower levels of methionine and lysine. Feed efficiency (body weight/feed consumption) to a fixed age was negatively associated with body weight, feed intake, frequency of leg disorders, and size of the abdominal fat pad. Its association with immunological and physiological traits varied with the environment. Apparent improvements in performance may be partially attributed to increases in growth rate, which have enabled broilers to reach market age at earlier ages.

Animals↗

PubMed1984

Production performance of white Leghorn layers limited fed.

Three trials were conducted to determine if the age at start of limited feeding or the amount of time laying hens were given to consume feed could be used to reduce feed intake without affecting egg weight (EW) or egg production. The age at start of limiting feed did not affect hen-day egg production (HDEP) or EW in any trial. In Trial 2, a significant difference in HDEP due to feeding times at 26 weeks of age was observed. Laying hens fed 7 hr/day at 26 weeks of age had a significantly lower HDEP than any other feeding time. Limited feeding in Trials 1 and 2 significantly decreased feed consumption, body weight gain (WG), and EW when compared with laying hens fed ad libitum. No difference in HDEP or EW was observed due to limited feeding in Trial 3. Laying hens fed 9 or 10 hr/day gained significantly less weight than laying hens fed ad libitum (Trial 3). Limited feeding did not improve feed efficiency in any trial. No consistent improvement in mortality could be attributed to limited feeding.

Age Factors↗

PubMed1984

Unique purified hydrated-gelatin diet for feeding dietary fiber to Wistar rats.

A purified hydrated gelatin diet was developed for feeding dietary fibers to Wistar rats. A dry fiber mix was prepared that consisted of 54.91 dextrose, 13.80 casein, 2.97 AIN mineral mix, 1.28 AIN vitamin mix, 0.17 dl-methionine, 6.80 lard and 5.10 gelatin (g/100g total dry feed). Either cellulose, hemicellulose, lignin, or pectin (15 g/100 g total dry feed) was added to the hydrated dry fiber mix and blended until complete distribution and hydration of the fiber was achieved. After gelling, these hydrated diets were stable for up to 24 hours in environmental conditions commonly encountered in animal facilities. Gel weep was minimal thus permitting feed consumption to be monitored conveniently by weighing the residue in the feeders. In situ examination of stomach contents after feeding such hydrated diets to rats indicated that the gelatin gel was readily degraded and did not confound gel formation by fiber itself. Feed efficiency values (g gain/100 kcal digestible energy) for these diets following a 26-day feeding trial were as follows: no fiber, 6.21; cellulose, 6.38; hemicellulose, 6.23; lignin, 6.52; and pectin, 5.53.

Animal Feed↗

PubMed1996

Effects of feeding cattle manure on growth performance and carcass characteristics of large white pigs.

Thirty-six weaner Large White piglets were randomly assigned to 3 replicates of 3 treatments to determine the effects of feeding 0, 10 or 20% of cattle manure in partial replacement of ground maize in the diet. The trial lasted 15 weeks. Feed efficiency was not significantly affected. However, pigs fed on the control diet consumed significantly more feed than pigs on the experimental diets containing cattle manure, and although their higher daily weight gain was not statistically significant, at the end of the trial they were significantly heavier (P < 0.05) than those fed the diet containing 20% cattle manure. Carcasses from pigs fed on the diets containing cattle manure were leaner than pigs fed on the control diet.

Animal Feed↗

PubMed2001

The effect of chlorocholine chloride (CCC) inclusion in the diets of growing hens on growth rate, oestrogen levels and the onset of lay.

A study was conducted to test the effect of chlorocholine chloride (CCC) on growth performance and the onset of laying in hens. One hundred and fifteen 3-week-old chickens were divided into four treatment groups of 39, 33, 31 and 12 chickens. They were placed on four dietary treatments consisting of 0 p.p.m. CCC (control), 5 p.p.m. CCC from 14 weeks of age (5 p.p.m. A), 5 p.p.m. CCC from the beginning (5 p.p.m. B), and 50 p.p.m. CCC from the beginning (50 p.p.m. B). The basal diets were formulated according to the growing period and were iso-nitrogenous and iso-energetic. The crude protein content was 17.99% dry matter and 14.63% dry matter during the first 3-8 weeks and 9-20 weeks, respectively. The energy content was 12.7 and 12.75 MJ metabolisable energy (ME)/kg dry matter for the respective two growth phases. Feed intake, bodyweight changes and egg production were measured. Blood samples for oestrogen determination were collected weekly from the 15th week until the first egg was laid. Depressive effects of 50 p.p.m. CCC on bodyweight gain during weeks 3-8 and feed efficiency over the whole period were observed. There were no treatment differences (p > 0.05) on feed intake, bodyweight gain during weeks 9-20 and age at the point of lay. CCC inclusion at 50 p.p.m. significantly (p < 0.05) stimulated the oestrogen concentration at 17 and 18 weeks of age, and was 65% higher than the control at 18 weeks.

Age Factors↗

PubMed1998

Rapid growth problems: ascites and skeletal deformities in broilers.

Over the last 40 yr, genetic selection for rapid growth and improved feed efficiency has been very effective in meat-type poultry. Combined with changes in the feed that have increased both the nutritional and physical density to encourage a high nutrient intake, growth rate has more than doubled. The effect of genetic selection for high muscle to bone ratio and high calorie intake of a ration that supplies all nutritional requirements causes significant mortality from cardiovascular disease. In the chicken, sudden death syndrome (flip-over) and pulmonary hypertension syndrome resulting in ascites are the most important. Ruptured aorta, spontaneous turkey cardiomyopathy (round heart), and cardiomyopathy causing sudden death produce high mortality in turkeys. Rapid growth induced by high nutrient intake alone can cause severe lameness, bone defects, and deformity, as these problems are seen in animals that have not been selected for rapid growth: dogs, horses, pigs, ratites and wild birds kept in zoologic gardens. In meat-type poultry, growth-related disease can be reduced or eliminated by reducing feed intake without affecting final body weight. Rapid growth alone may not be the pathogenic mechanism that results in cardiovascular or musculoskeletal defects. Metabolic imbalance induced by high nutrient intake may cause some of the conditions. These metabolic problems might be corrected without reducing growth rate.

Animal Welfare↗

PubMed2002

Nutrient use in chicks during the first week posthatch.

We examined effects of feeding chicks differing levels of macronutrients on performance during the first 7 d posthatch in this study. Four experiments were conducted using male Ross x Ross broiler chicks. The first experiment examined, in a 3 x 3 factorial design, the effect of feeding fat at 3, 7, and 11% and protein at 18, 23, and 28%. With increasing protein and fat levels feed intake and BW decreased. The second experiment examined, in a 3 x 2 factorial design, the effect of fat at 3, 7, and 10% and cellulose at 3 and 13%. Increasing fat in the diet decreased feed intake at both cellulose levels with little effect on BW. High cellulose decreased feed intake and BW. Experiment 3 examined, in a 3 x 2 factorial design, the effect of protein at 19, 23, and 27% and cellulose at 3 and 13%. Increasing protein levels decreased feed intake with little effect on BW. Cellulose decreased feed intake as levels increased. The fourth experiment examined, in a 4 x 2 factorial, the effect of feeding protein at 19, 21, 23, and 25% and fat at 4.5 and 9%, for 1 wk followed by standard diets through marketing. Significant differences in feed intake, BW and feed efficiency were observed at 7 d, but by 18 d differences were not significant and by 31 and 41 d no treatment effects were observed. Fat and protein percentage in the carcass in all experiments were not altered by dietary treatments and thus the efficiency of protein and fat retention decreased with increasing dietary intake. This study indicates that feeding diets with varying macronutrient levels to chicks during the first week post-hatch has distinct effects as compared to older broilers. It appears that once limiting amino acids and energy are provided the influence of dietary composition on immediate posthatch growth is limited.

Aging↗