Abdominal Fat Pad Size Research Articles

Leptin downregulates heat shock protein-70 (HSP-70) gene expression in chicken liver and hypothalamus

Heat shock protein (HSP)-70 is expressed in normal and stressed cells but is highly stress-inducible. Although leptin has long been suggested to be involved in the regulation of stress response, its interaction with the HSP-70 gene is still unknown, under both unstressed and stressed conditions. The present study has aimed to investigate the effect of leptin on HSP-70 gene expression in normal chicken liver, hypothalamus, and muscle. Continuous infusion of recombinant chicken leptin (8 mug/kg per hour) at a constant rate of 3 ml/h for 6 h in 3-week-old broiler chickens significantly (P < 0.05) decreased food intake and HSP-70 mRNA levels in liver and hypothalamus, but not in muscle. In an attempt to discriminate between the effect of leptin and of leptin-reduced food intake on HSP-70 gene expression, we also evaluated the effect of food deprivation on the same cellular responses in two broiler chicken lines genetically selected for low (LL) or high (FL) abdominal fat pad size. Food deprivation for 16 h did not affect HSP-70 gene expression in any of the studied tissues indicating that the effect of leptin was independent of the inhibition of food intake. Regardless of the nutritional status, HSP-70 mRNA levels were significantly (P < 0.05) higher in the hypothalamus of FL compared with LL chickens consistent with higher mRNA levels for hypothalamic corticotropin-releasing factor. To assess, whether the effects of leptin were direct or indirect, we carried out in vitro studies. Leptin treatments did not affect HSP-70 mRNA levels in a leghorn male hepatoma cell line or quail myoblast cell line suggesting that the effect of leptin on HSP-70 gene expression is mediated through the central nervous system. Furthermore, HSP-70 gene expression was gender-dependent with significantly (P < 0.05) higher levels in male than in female chickens.

Potential role of leptin in increase of fatty acid synthase gene expression in chicken liver

Leptin is reported to have direct effects on lipogenesis in peripheral tissues that are independent of its central effects on food intake and body weight. These experiments have been mainly carried out in rodents (different models of obesity) in which lipogenesis occurs in both adipose tissue and liver. Such effects are unknown in birds in which lipogenesis occurs essentially in the liver. In this study, leptin gene expression and circulating leptin levels were examined in two chicken lines, selected for high (FL) or low (LL) abdominal fat pad size, at different nutritional states (fasted and fed state). In addition, effects of recombinant chicken leptin on liver metabolism were investigated. Hepatic leptin and fatty acid synthase (FAS) gene expression and plasma leptin levels were significantly higher in FL than in LL chickens ( P < 0.05). In both lines, fasting significantly reduced hepatic leptin and FAS mRNA levels ( P < 0.05). Continuous administration of recombinant chicken leptin (8 μg/kg/h) during 6 h significantly inhibited food intake (51%) and increased leptinemia (23-fold) compared to untreated group. Despite the decrease of food intake, leptin significantly induced the expression of FAS in chicken liver. These changes were accompanied by a significant down-regulation of leptin receptor gene expression, however SREBP-1, the main transcription factor of lipogenic genes, remained unchanged. This result suggests a local potential role of leptin in the regulation of avian hepatic lipogenesis, and explain, at least partly, the metabolic changes evolved during the divergent selection of FL and LL chickens.

Effect Of L-Thyroxin Hormone (T4) On Compensatory Growth In Broiler Chicks

Purpose of researches in feed restriction area is improvement of feed efficiency, decrease of carcass fat content and abdominal fat pad size (Plavnik and Hurvitz,1991).Birds after early life feed restriction have less maintenance requirements due to decrease of heat increment and decrease of basal metabolic rate and specific dynamic action of food (Forsum et al.,1981).In many investigations, compensatory growth have not observed (Summers et al.,1990).It seems administration of Thyroid hormone after feed restriction can induce compensatory growth. The objective of the present study was to investigate the effect of early feed restriction and L-Thyroxin administration after early feed restriction on compensatory growth in broiler chickens.

Influence of dietary protein level on the broiler chicken's response to methionine and betaine supplements

Two experiments were conducted to compare broiler chicken responses to methionine and betaine supplements when fed diets with low protein and relatively high metabolizable energy levels (17%, 3.3 kcal/g) or moderate protein and lower metabolizable energy levels (24%, 3.0 kcal/g), resulting in different levels of carcass fat. In Experiment 1, the basal diets were formulated with corn, soybean meal, poultry by-product meal, and poultry oil. In Experiment 2, glucose monohydrate was also added, so that identical amino acid profiles could be maintained in the 17 and 24% protein diets. On average, feeding the 17 vs. 24% protein diet decreased 21-d body weight gain by 20%, increased feed conversion ratio (FCR) by 13%, and increased abdominal fat pad weight by 104%. Methionine and betaine supplements improved the performance of chicks fed the 24% protein diet in both experiments, as indicated by body weight gain and FCR. Only supplementary methionine increased performance of chicks fed 17% protein diets, and then only in Experiment 2. Neither methionine nor betaine decreased abdominal fat pad size in either experiment. Methionine supplementation decreased relative liver size and increased breast muscle protein. Both methionine and betaine increased sample feather weight, but when expressed as a percentage of body weight, no significant differences were detected. It is concluded that increasing carcass fat by manipulating percentage dietary protein level or amino acid balance does not influence betaine's activity as a lipotropic agent.

Metabolic Differences between Genetically Lean and Fat Chickens Are Partly Attributed to the Alteration of Insulin Signaling in Liver

Insulin signaling [tyrosine phosphorylation of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), Src homology and collagen protein (Shc) and phosphatidyl inositol 3′-kinase activity (PI 3′-kinase)] was studied in the liver and thigh muscles of fat (FL) and lean (LL) chickens. These lines result from a divergent selection on abdominal fat pad size. The divergence is of metabolic origin. Extreme nutritional states were studied (fed, 48-h starved and 30-min refed). Such conditions significantly altered insulin signaling in chicken liver, but surprisingly not in the muscle (except the phosphorylation of Shc in the refed state). No major differences that could account for this divergence were found in muscle. Liver IR number and Shc protein did not differ between genotypes. Liver IRS-1 (protein and messenger) was lower in the fed state and higher in the starved state in FL compared to that in LL chickens. In the fed state, tyrosine phosphorylation of liver IR, IRS-1 and Shc action was higher in FL than in LL chickens that in the absence of insulin resistance rely on higher plasma insulin levels. In the starved state, phosphorylation of liver IR was lower, but the phosphorylation of IR and IRS-1 were higher in LL than in FL chickens, most likely in response to higher plasma glucose and insulin in the lean genotype. In the refed state, the phosphorylation of liver IR and IRS-1 did not differ between genotypes despite significantly lower plasma insulin in FL chickens. Finally, PI 3′-kinase was not affected by the genotype. A significant activation of early steps of insulin signaling in liver of fed FL chickens may at least partly account for their increased liver lipogenesis and ultimately their fattening.

Lack of interrelationship between the effects of dietary factors and food withdrawal on carcase quality of broiler chickens

1. Four factorial experiments were carried out to determine whether there is any interrelationship between dietary energy-to-protein (E:P) ratio (experiments 1, 2 and 3) or pelleting the diet (experiment 4) and the duration of food withdrawal (FW), in their effect on carcase quality of broiler male chickens. The quality was evaluated by yields of carcase and breast meat, abdominal fat pad size, and the content and composition of the fat in the meat. The effect of sex on the response to FW was also determined in experiment 3 and that of age in experiment 4. 2. The diet with an E:P ratio higher than recommended decreased the weights of carcase and breast meat significantly (P 0.05) in 2 of the 3 experiments, and consistently increased the size of the abdominal fat pad and the fat content in thigh, but not in breast meat. Abdominal fat pad and the fat in meat of birds fed on this diet contained a significantly higher amount of oleic acid and a lower amount of linoleic acid, than the fat of birds fed on the diets with the recommended and the low E:P ratios. The pellets increased significantly the weights of carcase and breast meat and the relative size of abdominal fat pad. 3. FW for 24 h decreased significantly the weight at slaughter in all 4 experiments, carcase weight in 3 experiments, and breast weight in 1 experiment. However, it did not affect the relative size of the abdominal fat pad, the fat content in thigh and breast meat, and the composition of fatty acids in these tissues and in abdominal fat. None of the variables mentioned was affected significantly by the interaction between the dietary factors evaluated, sex or age of the birds on the one hand, and FW on the other hand. 4. It is concluded that the effect of 24 h of FW on weight at slaughter, carcase and breast meat weights and on fattening, is not affected by dietary E:P ratio, pelleting the diet, or sex and age of the broilers.

Research notes: Effect of environmental temperature on broiler chickens subjected to growth restriction at an early age

An experiment was carried out to evaluate the effect of early growth restriction (EGR) induced by feed restriction on the ability of male broiler chickens to withstand exposure to high environmental temperatures. A 2 x 4 factorial arrangement of treatments was employed to determine whether such an exposure affects the beneficial effect of EGR on performance and carcass quality. Chicks consumed feed ad libitum or were feed-restricted from 6 to 12 d of age (to achieve 60% growth of the ad libitum birds). From 4 to 8 wk of age, the chickens were kept in temperature-controlled chambers at 25, 30, 35 C and a diurnal cyclic temperature of 25:35 C. Weight gain, feed intake, and feed efficiency from 6 to 8 wk of age (after acclimatization to the various temperatures) and BW at 8 wk of age were significantly (P < or = 0.05) depressed by the high temperatures (35 and 25:35 C) compared with values observed at 25 and 30 C. Early growth restriction did not affect these variables. Relative heart, liver, and breast meat weights at 8 wk of age were decreased significantly with increasing temperature. Relative liver weight was also decreased significantly in the EGR chicks, whereas breast yield was increased significantly in these birds. Relative abdominal fat pad size was not affected by increasing the temperature from 25 to 35 C, but it was significantly lower in chickens kept at 25:35 C than in those kept at 25 and 35 C. Early growth restriction significantly reduced the size of abdominal fat. Because no significant interactions between EGR and ambient temperature on the above mentioned variables were observed during 4 to 8 wk of age, it is concluded that EGR can not alleviate the adverse effect of high ambient temperature on performance, nor can high ambient temperature obliterate the beneficial effect of EGR in improving feed efficiency and reducing fattening.

Changes in Body Composition and Adipocyte Cellularity of Male Broilers Subjected to Varying Degrees of Early-Life Feed Restriction

Three experiments were conducted to determine growth performance, body composition changes, and adipocyte characteristics of male broilers subjected to early-life feed restriction. The purpose of Experiment 1 was to determine 42-d growth performance and body composition changes. Treatments used were full-fed control and 50% physical feed restriction during the period 6 to 12 d of age. Experiment 2 was conducted to determine the adipocyte characteristics during and after feed restriction to 42 d of age. An additional treatment involved gradual refeeding following the feed restriction period. Experiment 3 was designed to test the effect of feeding different types of dietary fat during realimentation on the abdominal fat pad (AFP) size, and lasted until 18 d of age. Three types of fats were tested, namely animal-vegetable (A-V) blend, flax oil, and animal tallow, each represented by full-fed and feed-restricted treatments.Complete compensatory growth by feed-restricted birds relative to controls was not achieved by 42 d in either Experiments 1 or 2. Early feed restriction resulted in lower body fat percentage at 12 d (P < 0.05), although by 42 d a higher rate of fat deposition mainly by hypertrophy of adipocytes resulted in no difference in fatness. Gradual reintroduction into ad libitum feeding did not alter such adipocyte hypertrophy nor improve compensatory growth response during refeeding. There was consistent improvement in feed efficiency associated with early-life feed restriction (P < 0.05). The use of different types of dietary fat did not effect the AFP when expressed as percentage body weight. Birds that were fed A-V blend during the refeeding period had bigger AFP (grams per bird), a situation that is attributable to differences in body weight. Attainment of growth compensation by the feed-restricted broilers apparently requires a more prolonged growth period or a less severe feed restriction program than that used here. Saturation of dietary fat has no effect on realimentation characteristics of the broiler.

Computerized Early Feed Restriction Programs for Various Strains of Broilers

Two trials were conducted with broiler chickens in a nested design of two feeding programs [ad libitum (AL) or restriction (R)] and two strains of chicks. The Trial 1 R program was 50% AL rate from 6 to 14 days of age fed to Strains A and B. The trial 2 R program was 65% AL rate from 8 to 14 days of age fed to Strain B and C. A computer-controlled feeding system was used to regulate the R program in each trial. Broilers on R programs exhibited compensatory growth at 21, 35, and 45 days of age equivalent to that of AL programs in both trials. Feed efficiency was not affected in Trial 1 by broilers fed R (1.68) versus AL (1.73) at 42 days but was significantly affected at 63 days (R = 2.15 and AL = 1.93). Trial 2 showed no significant effect of R (1.89) versus AL (2.01) on feed efficiency. Strain effects on carcass yield was determined only at 42 days in Trial 1. Feeding program did not affect percentage carcass fat (Trial 1) or abdominal fat pad size (Trial 2). Feed restriction did significantly improve percentage bone ash in Trial 2.

Response of Broilers to Feed Restriction or Diet Dilution in the Finisher Period

Two experiments were conducted to study the response of 35- to 49-day-old male broilers to either feed restriction or diet dilution. In Experiment 1, after being fed conventional starter-grower diets to 35 days of age, birds consumed either a conventional finisher diet ad libitum, or 10, 20, 30, 40, or 50% less of this diet to 49 days of age. Performance and carcass characteristics were measured from 35 to 42 days and 42 to 49 days. There was a linear relationship between nutrient intake and 42- and 49-day body weight (P < .01). However, as a percentage of the control birds, weight gain was reduced less from 42 to 49 days (64%) than from 35 to 42 days (86%) for the 50% restricted group. Thus, there was apparently an adaptation in the period from 42 to 49 days.In a second comparable experiment, birds were offered a conventional finisher diet or one with either 10, 20, 30, 40, or 50% dilution with a 50:50 (wt:wt) mixture of sand:oat hulls. Growth rate was only slightly reduced, thus demonstrating the remarkable ability of the broilers at this age to increase feed intake in response to energy density of the diet. Although birds were of comparable weight, diet dilution resulted in a linear reduction in size of abdominal fat pad, whereas breast weight was not affected. The present data suggest that broiler chickens are far from eating to physical capacity, at 35 days of age, because they were able to exhibit up to a 70% increase in feed intake relative to the control birds.

Genetic Architecture of Carcass Composition in Chickens

A cross-sectional diallel experiment was used to estimate the contribution of various types of genetic variation for the chemical components of the chicken carcass. Populations tested included a commercially developed sire line (CM), a fertility-selected broiler line (FS), and the pureline Jersey Giant (JG). Average line effects were significant for body weight and total carcass water, fat, and protein. Line effects were significant only for percentage fat and water. Maternal effects and additive sex linkage were not significant for any carcass component on an absolute or percentage basis. Significant average heterosis and sex by heterosis interactions were observed for abdominal fat pad weight and total carcass fat. Male hybrids exhibited a 29% decrease in abdominal fat pad size, but female hybrids exhibited a 7% increase. Significant heterosis was observed among females, but not males, for percentage carcass fat. Changes in carcass fat via hybridization produced the largest percentage change among males due to heterosis of the sex chromosomes. In the present experiment, negative heterosis for abdominal fat among male progeny accounted for approximately 65% of the overall reduction in fat content of the carcass.

The nutritive evaluation of dried poultry excreta as a feed ingredient for broiler chickens

In the first of two experiments, the effect of graded levels of oven or solar dried poultry excreta (DPE) on broiler performance, carcass yield, abdominal fat pad weight and thigh meat composition was examined. Excreta were collected every 3 days from laying hens and immediately dried in an oven at 60 °C or in a solar drier at 50–70 °C and milled. The DPE was included in broiler diets at levels of 0, 5, 10, 15 and 20%. The diets were made both isoenergetic and isonitrogenous. The type and level of DPE had no significant effect on growth rate. Inclusion of DPE affected ( P < 0.05) feed intake, although no difference was noted between the types of DPE. Neither inclusion nor level of DPE had a significant effect on feed efficiency. Dried poultry excreta had variable effects on abdominal fat pad size, carcass yield, and thigh meat composition. A significantly higher carcass yield was obtained in the control group than in the other groups. In the second experiment, utilization of DPE at various levels of energy and protein was evaluated. Broiler starter diets containing 10% DPE were formulated to have 11.51 MJ apparent metabolizable energy (AME) kg −1, 11.97 MJ AME kg −1 and 11.43 MJ AME kg −1, with 20.8%, 21.7% and 22.5% crude protein, respectively. Finisher diets were formulated to contain the same energy levels but with crude protein contents of 18.2%, 19.2% and 20.0%, respectively. No significant differences were observed in broiler performance, carcass yield or meat composition of broilers fed on these diets from 1 to 54 days of age. With proper adjustments of energy and protein to meet the broilers' requirements, oven or solar dried poultry waste can be safely included at levels of up to 20% of broiler diets.

Effects of high concentrations of dietary vitamin e and ethoxyquin on the performance of laying hens1

1. Three experiments were carried out with light strain laying hens to evaluate the effects of relatively high doses of dietary vitamin E (125 mg/kg food) or ethoxyquin (EQ) (250 mg/kg food) on their laying performance. The control diet contained 5 and 125 mg/kg vitamin E and EQ, respectively. The experimental diets were fed either from one or 32 weeks until 88 or 89 weeks of age. 2. The two antioxidants did not affect the growth of the pullets, age at first egg, final body weight, average egg weight or relative abdominal fat pad size and liver weight at the termination of the experiments. In two out of three experiments, vitamin E and EQ did not affect egg production, food efficiency or mortality; in the third experiment vitamin E significantly (P less than 0.05) improved egg production and food efficiency after an outbreak of Newcastle disease which occurred at 34 weeks of age. EQ significantly reduced mortality during the course of this experiment, but did affect the variables of performance. In two experiments vitamin E consistently improved shell density, although a significant effect was observed in only one of the eight determinations carried out. EQ did not affect this variable. 3. The uterine muscle was more susceptible to oxidation than the drumstick meat, as evaluated by TBA values. In both tissues, vitamin E significantly and consistently decreased TBA values and restricted their increase during incubation, while EQ was less effective, particularly in the drumstick meat. 4. It is concluded that increasing vitamin E and EQ concentrations in diets of laying hens have no effect on the decrease in egg production due to aging. However, vitamin E may minimize the decline in egg production and food efficiency following the outbreaks of some diseases and slightly improve--under certain yet undefined conditions--shell density.

Effect of pulsatile or continuous administration of pituitary-derived chicken growth hormone (p-cGH) on lipid metabolism in broiler pullets

1. The effects of pulsatile and continuous intravenous administration of exogenous, pituitary-derived chicken growth hormone (p-cGH) on lipid metabolism and endocrine/metabolite levels of broiler-strain pullets were studied. 2. Eight-week-old pullets were administered p-cGH or vehicle over a 10 min period every 90 min for 7 days. 3. Pullets were also administered the same daily amount (123 μg/kg of body weight/day) continuously for 7 days. 4. Feed intake, body weight gain, in vitro lipogenesis and hepatic enzyme activities were determined with certain hormones identified with the control of growth. 5. Pulsatile p-cGH administration for 7 days lacked effect on weight gain, feed efficiency, muscle or bone development. 6. Abdominal fat pad size was decreased ( P < 0.05) by pulsatile but not continuous administration of p-cGH. Pulsatile p-cGH administration also decreased ( P < 0.05) in vitro lipogenesis. Liver malic enzyme and isocitrate dehydrogenase activities were increased ( P < 0.05) by pulsatile but not continuous administration of p-cGH. In contrast, glutamic oxaloacetic transaminase activity was increased by a continuous infusion of p-cGH. 7. Plasma concentrations of T 4 corticosterone and triglycerides were decreased ( P < 0.05) by a pulsatile but not a constant infusion of p-cGH. 8. Plasma T 3 and GH were increased ( P < 0.05) by pulsatile p-cGH compared to both a continuous infusion of p-cGH and the saline controls. 9. This study is the first to prove that in the broiler chicken, the pattern of exogenous p-cGH administration is a factor influencing in vitro responses to the hormone.

RESPONSE OF MALE AND FEMALE BROILERS TO DIET PROTEIN

Two experiments were conducted to note the broilers' response to graded levels of dietary protein (CP). Female birds were fed one of six diet series ranging from 22–20–18 to 18–18–16% CP from 0–21 days, 21–35 days and 35–42 days, respectively. Males were fed diet series from 28–24–22 to 20–18–16 over the same time periods (Table 1). Each diet program was tested with four replicate groups of 60 birds. Body weight and feed intake were monitored at time of feed change-over and at termination of experiment. Twenty birds per replicate were used for carcass analyses. Females were heavier when diets of higher protein content were offered (P &lt; 0.05). These birds consumed more feed (P &lt; 0.05) but exhibited feed efficiency that was not different to birds fed diets of lower protein content. Carcass weight and breast meat yield were not influenced by diet, although higher-protein diet series resulted in reduced proportional abdominal fat pad size (P &lt; 0.01). Diet protein had no effect on body weight of male birds at 42 d (P &gt; 0.05). Male birds reared on a program involving die lowest CP levels of 20–18–16 exhibited inferior feed utilization relative to birds from most other treatments (P &lt; 0.05). Programs with low-protein diets for males resulted in reduced carcass weight, reduced breast meat yield and increased abdominal fat deposition (P &lt; 0.05). It is concluded that male birds can be reared on very low protein diets without loss of weight, although carcass quality will be inferior. Female broilers are heavier when diet protein intake is increased through use of diets with higher protein content. Key words: Broiler, diet protein, performance, carcass composition

Effect of pattern of administration on the response to exogenous, pituitary-derived chicken growth hormone by broiler-strain pullets

The effect of pulsatile versus continuous intravenous administration of exogenous, pituitary-derived chicken growth hormone (cGH) on growth performance and endocrine/ metabolite status of broiler-strain pullets was determined. In a first study, 8-week-old pullets, surgically prepared with intravenous catheters and maintained via a fluid swivel/spring tether/harness system, were administered cGH or vehicle (control) over a 10-min period every 90 min (i.e., 90-min pulse pattern) for 21 consecutive days. Feed intake, body weight gain, and carcass yield and composition were determined in conjunction with plasma concentrations of several hormones and metabolites. In a second study, 8-week-old pullets were intravenously administered cGH or vehicle continuously fur 21 consecutive days under the same conditions as for Study I. Pulsatile cGH administration improved feed efficiency ( P < 0.02), increased longitudinal bone growth ( P < 0.02) and mass ( P < 0.01), and reduced abdominal fat pad size ( P < 0.05) and total carcass lipid ( P < 0.09) over the 21-day treatment period in comparison to vehicle infusion. Pulsatile cGH administration also resulted in hepatomegaly, a marked elevation in plasma IGF-I ( P < 0.003) and T 3 ( P < 0.005) concentrations, and a reduction in plasma T 4 levels ( P < 0.04). In contrast to the above responses to pulsatile cGH, continuous intravenous cGH administration significantly impaired feed efficiency ( P < 0.01) and had no significant effect on abdominal fat pad or liver size or on total carcass lipid, but did result in widening of the epiphyseal growth plate ( P < 0.06) and increased bone mass ( P < 0.01) in comparison to vehicle infused controls. These studies demonstrate that in the broiler chicken, for which endogenous plasma GH concentrations are pulsatile at early ages in conjunction with rapid growth, the pattern of exogenous GH administration is clearly a factor influencing the nature of response to the hormone.

Effect of Early Nutrition on Abdominal Fat in Broilers

Experiments were conducted to investigate the effect of isocaloric diets varying in protein and fat content or diluted with a combination of cellulose and sand during the 1st wk of life on subsequent abdominal fat pad size in male broiler chicks. In the first experiment chicks were fed diets containing 2,850 kcal metabolizable energy (ME)/kg with 23% protein and low or high total fat (23/LF or 23/HF) or 28% protein with low fat (28/LF) for the 1st 7 days and diets with varying protein and fat levels during the next 19 days. Abdominal fat was significantly higher in chicks fed 28/LF for 7 days followed by 23/HF than for the other treatments. In a second experiment chicks in battery brooders were fed diets with 18, 23, or 28% protein with or without added fat. They were then intermingled and placed in floor pens where they were fed corn-soy starter grower and finisher diets to 7 wk. Body weight at 4 and 7 wk and abdominal fat at 4 wk were not significantly different among treatments, but abdominal fat at 7 wk was significantly higher for chicks fed the 28/LF or 28/HF diets. Effects of feeding the same 18/LF, 23/LF, and 28/LF diets or practical diets containing 3,150 kcal ME/kg with various protein levels during the first week were examined in another experiment. Chicks all received the same diets from 7 to 49 days. No significant differences in size of abdominal fat pad was observed within each diet series. A final experiment was conducted to determine the effect on abdominal fat content of diluting a 23% protein, 3,150 kcal ME/kg diet with levels of 0 to 10% cellulose:sand (1:2 ratio) during the 1st 7 days followed by feeding the same practical diets to intermingled chicks from 7 to 49 days of age. No difference in body weight was observed but abdominal fat of birds fed 2.5% cellulose:sand was significantly higher than birds fed 0 or 10% cellulose:sand. Results of these experiments show that abdominal fat content in market broilers may be influenced by the composition of the diet fed during the first week of life.

Effect of early nutrition on fattening and growth of broiler chicks at 7 weeks of age.

1. Six experiments were carried out with male and female broiler chicks in a factorial arrangement to evaluate the combined effects of fat concentration or energy-to-protein (E:P) ratio in diets fed from 1 to 7 or 14 d of age, and of the E:P ratio in diets fed from 1 or 2 to 7 weeks of age on fattening and performance of the birds. 2. Diets with a wide E:P ratio fed from 1 or 2 to 7 weeks consistently and significantly increased abdominal fat pad size at 7 weeks of age. On the other hand, in 5 of the experiments, the nutritional treatments from 1 to 7 or 14 d did not significantly affect this variable in chicks fed on diets with either the narrow or the wide E:P ratio. 3. Body weights and food utilisation at 7 or 14 d were consistently and significantly improved by increasing dietary fat concentration and using diets with a narrow E:P ratio. However, at 7 weeks of age, in only two of the experiments were body weights still significantly affected by early nutrition. 4. Diets with a wide E:P ratio consistently and significantly reduced the performance of chicks up to 4 weeks of age. Nevertheless, at 7 weeks of age the performance of these chicks tended to be better (at times significantly so) in most of the experiments, despite their excess fattening.

Abdominal Fat Deposition and Sudden Death Syndrome in Broilers: The Effects of Restricted Intake, Early Life Caloric (Fat) Restriction, and Calorie: Protein Ratio

The effects of feed restriction, early life fat restriction, and calorie:protein ratio on abdominal fat pad development and sudden death syndrome (SDS) in the broiler chicken were studied in two experiments. In Experiment 1, restricting feed intake to 90% of ad libitum intake was found to reduce significantly (P<.01) both 49-day body weights and abdominal fat pad size while feed efficiency was significantly (P<.01) improved compared to groups fed a wheat diet ad libitum. Corn-fed birds tended to outperform wheat fed groups. Reduced growth rate or supplementation of the diet with additional vitamins and minerals did not effect the incidence of SDS. In Experiment 2, fat restriction in the diet from 0 to 7 days initially reduced growth rate and increased feed:gain ratios. By 49 days, no effect of fat restriction on these parameters was observed. Dietary fat restriction tended to increase abdominal fat measured at 49 days of age. Lowering the calorie: protein ratio of the finishing diet significantly (P<.05) improved feed: gain ratios measured from 29 to 49 days and tended to reduce fat pad size. Incidence of SDS was significantly (P<.05) lower from 29 to 56 days in groups fed the 24% protein finisher diet as compared to birds fed a 19% finisher diet.

The Influence of Dietary Energy and Amino Acid Levels on Abdominal Fat Pad Development of the Broiler Chicken

A study was conducted to determine the effects of dietary energy and amino acid content on the weight of the abdominal fat pad of broiler chicks. Diets containing 2970, 3190, and 3410 ME kcal/kg were formulated to contain 70 to 120% of the 1977 NRC amino acid requirements. These diets were fed to broiler chick s for 57 days. After slaughter in a commercial processing plant carcasses were evaluated.Through the dietary manipulations it was possible to produce carcasses of widely varying abdominal fat pad size. Although total fat pad weight was directly influenced by the dietary energy level of the diets, covariance adjustments for differences in body weight markedly reduced the influence of dietary energy. The degree of fatness could be significantly reduced by increasing the dietary amino acid levels within a given energy level.