Factors influencing the quantity of abdominal fat in broilers. 3. Dietary energy levels

The effect of sodium stearoyl-2-lactylate (80%) and tween 20 (20%) supplementation in low-energy density diets on growth performance, nutrient digestibility, meat quality, relative organ weight, serum lipid profiles, and excreta microbiota in broilers

A total of 768 1-d-old Ross 308 male broiler chickens with an average body weight of 43.64 ± 0.59 g were used in a 5-wk feeding trial. The chickens were distributed into 4 treatments of 12 replications per treatment with 16 chickens per pen. Dietary treatments included the following: TRT1, basal diet; TRT2, -40 kcal diet + 0.05% emulsifier; TRT3, -60 kcal diet + 0.05% emulsifier; TRT4, -80 kcal diet + 0.05% emulsifier. The emulsifier contained 80% sodium stearoyl-2-lactylate and 20% tween 20. In our study, the treatment diets had no significant effect on growth performance, meat quality, relative organ weight, serum lipid profiles, and excreta microbiota. However, the birds were able to grow as well with less energy when the emulsifier was added. The supplementation of emulsifier in the low-energy diet linearly decreased cholesterol (P = 0.099) and LDL/C (P = 0.074). The fat digestion of broilers fed with TRT2, TRT3, and TRT4 was significantly higher than broilers fed with TRT1 diet. Our study result shows that the emulsifier used for the experiment is beneficial in the low-energy diet of broiler chickens.

Effects of dietary supplementation of emulsifier and carbohydrase on the growth performance, serum cholesterol and breast meat fatty acids profile of broiler chickens

A total of 540 2-day-old male Ross 308 broilers were used in a 35-day experiment and were randomly divided into five treatments: (i) NC (low energy); (ii) PC (high energy diet); (iii) P1 (NC + 0.1% carbohydrases); (iv) P2 (NC + 0.05% emulsifier); and (v) P3 (NC + 0.1% carbohydrases + 0.05% emulsifier). From days 0 to 21, body weight gain in PC and P3 treatments increased (P < 0.05) compared with NC treatment. The chicks fed PC, P1, P2 and P3 improved (P < 0.05) feed conversion ratio compared with the NC treatment throughout the whole experiment. Abdominal fat weight was heavier (P < 0.05) in PC, P2 and P3 treatments than in NC and P1 treatments. On day 35, serum total cholesterol and low density lipoprotein cholesterol concentration were higher (P < 0.05) and high-density lipoprotein cholesterol was lower (P < 0.05) in NC and P2 treatments than in PC, P1 and P3 treatments. The concentration of oleic acid, linoleic acid and total unsaturated fatty acids were highest (P < 0.05) in PC than in the other treatments. In conclusion, the results indicate that low energy density diet had lower growth performance, while the inclusion of emulsifier and carbohydrases in low energy diets can partially improve growth performance.

Tolerance and safety evaluation ofN,N-dimethylglycine, a naturally occurring organic compound, as a feed additive in broiler diets

N,N-dimethylglycine (DMG) is a tertiary amino acid that naturally occurs as an intermediate metabolite in choline-to-glycine metabolism. The objective of the present trial was to evaluate tolerance, safety and bioaccumulation of dietary DMG in broilers when supplemented at 1 g and 10 g Na-DMG/kg. A feeding trial was conducted using 480 1-d-old broiler chicks that were randomly allocated to twenty-four pens and fed one of three test diets added with 0, 1 or 10 g Na-DMG/kg during a 39 d growth period. Production performance was recorded to assess tolerance and efficacy of the supplement. At the end of the trial, toxicity was evaluated by means of haematology, plasma biochemistry and histopathology of liver, kidney and heart (n12), whereas bioaccumulation was assessed on breast meat, liver, blood, kidney and adipose tissue (n8). Carcass traits were similar between the control and 1 g Na-DMG/kg feed groups (P>0·05), but the feed:gain ratio was significantly improved at 1 g Na-DMG/kg feed compared with the control or the 10-fold dose (P = 0·008). Histological examinations showed no pathological effects and results of haematology and plasma biochemistry revealed similar values between the test groups (P>0·05). Bioaccumulation occurred at the 10-fold dose, but the resulting DMG content in breast meat was comparable with, for instance, wheat bran and much lower than uncooked spinach. In conclusion, DMG at 1 g Na-DMG/kg improved the feed:gain ratio in broilers without DMG being accumulated in consumer parts. Furthermore, dietary supplementation with DMG up to 10 g Na-DMG/kg did not induce toxicity or impaired performance in broilers.

[The effect of enzyme supplements and high amounts of white lupins on concentrations of lipids in serum and meat in fattening chickens]

A bi-factorial experiment was conducted to investigate the effect of enzyme supplements (200 mg Roxazyme G per kg feed) and white lupins (35%, freshly harvested or stored) on concentrations of lipids in serum and lipoproteins as well as in chest and leg meat. Enzyme supplements had not any effect on concentrations of cholesterol, triglycerides and phospholipids in serum and lipoproteins and on concentrations of triglycerides and cholesterol in meat. In contrast, feeding the rations with 35% lupins lowered concentrations of triglycerides and phospholipids in serum as well as concentrations of total cholesterol, triglycerides and phospholipids in high-density lipoproteins. However, freshly harvested and stored lupins partially had different effects on those parameters. Lipids in low-density lipoproteins were not affected by lupins. Feeding the rations with 35% lupins increased triglyceride concentrations in thigh muscle whereas triglyceride concentration in chest muscle as well as cholesterol concentration in both pieces were not changed. Clinical-chemical parameters related to protein metabolism were not affected by either enzyme supplements or lupins.

Effect of age and carcase composition on the onset of sexual maturity in quail under normal feeding regimens

1. The effect of age and carcase composition on the onset of sexual maturity was investigated in Japanese quail (Coturnix coturnix japonica) reared under a normal feeding regimen. 2. At 42 d of age, when the quail had started to lay and hen day production was about 60%, layers were heavier and contained more carcase fat than those that were not laying. 3. The liver and the ovary weight were greater following the onset of sexual maturity than 1 or 2 weeks before (35 and 28 d respectively). 4. Carcase fat as well as age are critical requirements for the onset of sexual maturity in quail.

Effect of nutrition on broiler carcase composition: influence of dietary energy content in the starter and finisher phases

Three isonitrogenous starter (230 g/kg) and three finisher diets (200 g/kg) were formulated to contain 10.78, 12.78 and 14.78 MJ AME/kg and fed to 1512 male and female broilers such that there were 9 treatment combinations. Birds fed the low-energy starter diet were significantly lighter (P less than 0.05) and their carcases contained proportionally less abdominal fat and total carcase fat at 24 d of age. This effect remained until 49 d of age irrespective of the finisher diet fed. The energy content of the finisher diet had no significant effect on bodyweight but the proportion of abdominal fat and total carcase fat deposited was lower for birds fed the low-energy finisher.

Effect of diet and early quantitative feed restriction on the minimum weight requirement for onset of sexual maturity in white rock broiler breeders

The effect of diet and feed restriction on minimum weight for onset of sexual maturity was studied in White Rock broiler breeders. In the restriction experiment, three groups of birds were subjected to moderate, severe, and very severe quantitative food restriction during the rearing period (19 week target weights: 1900, 1300, and 700 g, respectively). From 20 to 24 weeks body weight was equalized at 2200 g, and from 24 weeks birds were allowed to gain about 150 g/week until first egg. In the diet experiment, two groups of birds were raised under severe quantitative food restriction during the rearing period and then allowed to gain about 150 g/week on a low metabolizable energy/protein (ME/P) ratio diet (25.4% protein, ME/P = 116) and on a high ME/P ratio (14.7% protein, ME/P = 219) until first egg. All birds were killed at first egg. Birds of the three restriction groups entered lay at the same lean body weight and ash and protein content, but at different age, carcass weight, shank length, dry matter, and fat content. Birds of the two diet groups entered lay at the same lean body weight, shank length, and ash content but at different carcass weight, dry matter, and fat content. Considering both experiments together, birds of the different treatment groups entered lay at similar lean body weight and ash content but differed in age, carcass weight, shank length, dry matter, and fat content.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary protein and energy on broiler carcass composition and efficiency of nutrient utilization

Day-old broilers were offered diets varying in dietary protein (16, 20, 24, 28, 32, 36%) and energy (2600, 2800, 3000, 3200, 3400, 3600 kcal [metabolizable energy] ME/kg) to 49 days of age to determine the effect of alteration in nutrient density on carcass composition and efficiency of nutrient utilization. Abdominal and total carcass fat contents responded similarly to alterations in dietary protein and energy, whether expressed on a percentage or absolute weight basis. However, maximum protein deposition occurred with the 20% crude protein diet, in contrast to the increase in percent carcass protein observed above this level. Although percent carcass protein decreased throughout the energy range tested, absolute carcass protein remained constant regardless of the dietary energy level. Dietary protein exerted similar effects on both absolute and percent carcass moisture. However, an increase in dietary energy resulted in a decrease in percent carcass moisture and an increase in absolute carcass moisture. Protein utilization decreased with each increment of dietary protein but increases in dietary energy resulted in small increases in protein utilization throughout the range tested. Changes in dietary protein and energy resulted in small differences in efficiency of energy utilization. Regression equations derived for carcass composition demonstrated that although diet composition is inadequate as a predictor of carcass parameters, the addition of carcass moisture (%) to the equation improves the reliability of the estimate. Equations for the prediction of nutrient utilization from diet composition are also presented.

Dietary energy and fat content as factors in the nutrition of developing egg strain pullets and young hens. 4. Effect on growth, hepatic lipogenic enzyme activity and body chemical composition of White Leghorn pullets from hatch to 20 weeks of age

Nine starting and rearing diets (three energy levels each with three fat levels) were fed to commercial White Leghorn chicks from hatch to 20 weeks of age. As noted in the earlier papers of this series, pullets fed the high energy rearing diets showed significant (P = 0.05) reductions in feed intake, however, average daily caloric intake was greater (P = 0.05) for pullets consuming the low energy rearing diets. Fat content of the diet had not influence on either daily feed (g.) or caloric (kcal.) intake. Energy content of the diets failed (P = 0.05) to affect parameters related to body growth and development, hepatic citrate-cleavage and "malic" enzyme activity and liver or body composition. Fat content of the diet depressed hepatic enzyme activity while no effect was noted on body weight, liver weight or body composition. The onset of sexual maturity altered lipid metabolism in the developing pullets. Significant (P = 0.05) energy level by fat level interactions were noted in only two of the 20 parameters studied in this experiment. In vitro assay of hepatic citrate-cleavage and "malic" enzyme activity proved to be of little value in predicting hepatic lipogenic activity and subsequent effects on liver and total body composition.