Energy utilisation in germ-free and conventional chicks fed diets containing sorbose

1. In experiment 1, growing conventional (CV) chicks were fed on diets containing graded amounts (0, 100, 200 and 300 g/kg diet) of sorbose from 4 to 14 d. Protein, fat and energy deposition were determined after carcase analysis. The values for growth, food efficiency, metabolisable energy (ME) and fat and energy depositions declined as the dietary sorbose content increased. 2. In experiment 2, the performances of germ-free (GF) and CV chicks fed on diets with (100 g sorbose/kg diet) or without sorbose were investigated. On both diets, body weight gain, food consumption and protein accumulation in GF chicks were significantly higher than those in CV birds. No significant differences were observed between the dietary treatment except for ME values, which were significantly lower for the sorbose diet. 3. It is suggested that dietary sorbose decreased energy utilisation, and that the microbial contribution to the utilisation of dietary sorbose was negligible in the chicken.     

Influence of energy intake on growth and utilisation of dietary protein and energy in germ-free and conventional chicks

The effect of metabolisable energy (ME) intake on the growth and utilisation of dietary protein and energy in germ-free (GF) and conventional (CV) chicks was investigated in two experiments. In experiment 1 a high energy diet (HED, 14.8 kJ ME/g) and a marginally-adequate energy diet (AED, 11.7 kJ ME/g) were fed to the GF and CV chicks at 240 g/2 birds/10 d. In experiment 2 a diet with 13.7 kJ ME/g was fed at 118 g (low level, LL) or 128 g (high level, HL)/bird/10 d. Body weight gain, protein retention and protein retention rate were similar in GF and CV chicks on both AED and HED in the first experiment, but in the second were higher in GF than in CV chicks. The increased ME intake of the CV chicks in experiment 2 may be too small to compensate for the increased requirement. ME intake was significantly higher in the CV chicks than in the GF chicks, whereas energy retention was similar in both groups.     

Effect of the gut Microflora on the size and weight of organs of chicks fed diets of different protein content

1. Germ‐free (GF) and conventional (CV) chicks were reared for 14 d on diets containing 50 (LD), 200 (AD) and 400 (HD) g protein/kg. Food and water were provided ad libitum. The size and weight of the proven‐triculus, gizzard, duodenum, jejunum, ileum, caeca, colon, liver, pancreas, heart, spleen, adrenal glands and kidneys were measured, and liver composition was examined.

2. The absolute and relative (weight/kg body‐weight) weights of the intestine of CV chicks fed AD and HD diets were greater than those of GF chicks. The LD diet did not affect the absolute and relative weights of the duodenum and jejunum.

3. The absolute weight, relative weight and fat content of the liver of GF chicks given LD diet were greater than those of their CV counterparts.

4. The size and weight of some organs are affected by the diet (dietary protein content)‐microflora‐host interaction.

     

Effect of short chain fatty acids on the performance and intestinal weight in germ-free and conventional chicks

1. In experiment 1, the performance and tissue weights of germ-free (GF) and conventional (CV) chicks fed on diets containing 25.4 g acetic acid/kg diet (AD) or 25.4 g kaolin/kg diet (KD) were investigated. Body weight gain in GF chicks was significantly higher on the AD, but significantly lower on the KD compared with their CV counterparts. The values for food efficiency, protein retention and energy retention followed a similar pattern to that of the body weight gain. 2. The weights of all sections of the intestine except the colon were significantly greater in CV chicks. In CV but not in GF birds the jejunum and ileum were heavier from birds fed on the AD than from those on the KD diet. 3. In experiment 2, the influence of butyric acid administration on the weight of some organs in chicks was investigated. The weight of duodenum, jejunum and ileum was significantly increased by intraperitoneal administration of butyric acid (2 ml of 100 mM solution/d) for 4 d, but no significant effect was observed by oral administration. 4. It might be suggested that short chain fatty acids such as acetic and butyric acids formed by bacterial action in the crop and subsequently absorbed are at least partly responsible for the heavier gut weight in CV birds.     

Effect of dietary medium chain triglyceride on protein and energy utilisation in growing chicks.

1. Protein, fat and energy retentions of chicks fed on diets containing medium chain triglyceride (MCT) and long chain triglyceride (LCT), at 100 and 200 g fat/kg diet, were investigated. Maize oil was used as the LCT source. The MCT used was glyceryl tricaprylate. 2. Body weight gain and food intake were decreased with the diets containing MCT and these effects were greater at the higher fat concentration. Protein retention was also reduced by dietary MCT, although the efficiency of protein utilisation (protein retained/protein intake) was not altered. 3. The values for fat and energy retentions were significantly lower in the chicks fed on the MCT-supplemented diets than in those receiving the LCT-containing diets. Dietary ME values and efficiencies for energy utilisation (energy retained/ME intake) were also reduced by dietary MCT.     

Improvement of dietary protein utilisation in chicks by medium chain triglyceride

1. To improve the influence of variation of ME intake, an experiment was carried out using equalised feeding to investigate the comparative effects on protein and energy utilisation in chicks of diets containing medium chain triglyceride (MCT) and long chain triglyceride (LCT). Experimental diets were given at 3 different food intakes, namely, 100, 120 or 147 g/bird/10 d. The diets contained MCT or LCT on an isoenergetic basis. Maize oil and caprylic acid triglyceride respectively, were used as LCT and MCT sources.

2. Body weight gain and food efficiency of chicks significantly increased with the supplement of dietary MCT compared with dietary LCT at all food intakes. Protein retention and the efficiency of protein utilisation (protein retained/protein intake) at all food intakes also significantly increased with dietary MCT, while body fat and fat retention were significantly reduced. Chicks fed the LCT‐supple‐mented diet, on the other hand, had a lower protein retention, but significantly higher fat retention. The value for energy retention and the efficiency of energy utilisation (energy retained/ME intake) were not significantly different between MCT‐ and LCT‐supplemented diets.

3. It was concluded that supplementing MCT to the chick diet would improve body weight gain and protein utilisation while regulating fat deposition compared to the LCT supplemented diet, under equalised feeding conditions.     

Dietary L-carnitine increases plasma insulin-like growth factor-I concentration in chicks fed a diet with adequate dietary protein level

1. The effect of L-carnitine supplemented into experimental diets with varying dietary protein concentrations (50, 200 and 400 g/kg) on body weight gain and plasma insulin-like growth factor-I (IGF-I) concentration in chicks was examined. 2. Dietary L-carnitine supplementation provided 0, 200, 500 and 1000 mg/kg. Chicks were given the diet ad libitum for 10 d. 3. When L-carnitine was provided as 500 or 1000 mg/kg, body weight gain was significantly improved in birds receiving the 200 and 400 g protein/kg diets. 4. There was an interaction between dietary L-carnitine and protein content on plasma IGF-I concentration. L-carnitine supplementation had little influence on plasma IGF-I concentrations in birds receiving the low protein (50 g/kg) diet. When dietary L-carnitine concentrations were increased from 0 to 1000 mg/kg in the adequate protein (200 g/kg) diet, plasma IGF-I concentrations were also increased. However, when dietary L-carnitine content was more than 500 mg/kg in the 400 g/kg protein group, plasma IGF-I concentration decreased with increasing dietary L-carnitine content. 5. Body weight change correlated significantly with the alteration in plasma IGF-I concentrations in chicks given diets with adequate dietary protein. 6. In conclusion, the improvement in body weight gain caused by dietary L-carnitine supplementation was achieved when chicks were given their dietary protein requirement, which may be partially explained by an increase in plasma IGF-I concentration.     

Protein requirement of fast- and slow-growing chicks

1. Responses of male broiler chicks and male chicks of an egg-laying stock to dietary crude protein (CP) concentrations ranging from 167 to 251 g/kg (metabolisable energy content 13 MJ/kg) were compared from 0 to 21 d of age, using 20 groups of 9 or 10 chicks (5 diets x 2 stocks x 2 replicates). 2. Average growth rate in the broilers was three times that of the layer chicks. The broilers needed at least 251 g CP/kg to maximise their liveweight gain but the layer chicks needed only about 188 g CP/kg. 3. The broiler chicks ate less than twice as much food as the layers and their maximum gain/food ratio was 0.6 compared with 0.4 for the layer chicks. These maximum efficiencies of conversion of food to liveweight were achieved in both cases with a diet containing 230 g CP/kg. 4. The efficiency of protein utilisation (above maintenance) was the same in fast- and slow-growing genotypes (about 0.47 g protein gain/g protein consumed). 5. Carcase analysis at 3 weeks of age showed that the broilers had deposited more fat than the layers and that protein content of the diet had markedly influenced fat deposition in both stocks. Fat in the whole body increased from 29 to 87 g/kg in the layer chicks and from 81 to 123 g/kg in the broilers as dietary protein was reduced from 251 to 167 g/kg. 6. The optimum protein to energy ratio of a chick starter diet will depend on the growth potential of the stock, as well as the cost of ingredients and the value of fatter or leaner carcases.     

Effect of cellulase supplementation in low-crude protein diets on performance, nitrogen excretion, fat deposition, hepatic lipogenic and lipolytic enzyme activity in broilers

1. Two experiments were conducted to investigate the effect of dietary enzyme supplementation of a low-protein diet on performance, nitrogen excretion, fat deposition, hepatic lipogenic and lipolytic enzyme activity in 7-21- (Experiment 1) and 21-42-d-old (Experiment 2) male broiler chicks. 2. Chicks were given diets containing 210 g (Experiment 1) or 170 g (Experiment 2) crude protein (CP)/kg (Control), amino acid-fortified diets 190 g (Experiment 1) and 150 g (Experiment 2) CP/kg (Low-protein), and a low-protein diet supplemented with 1000 U/kg of cellulase. 3. In Experiment 1, growth performance and abdominal fat deposition were not affected by dietary treatments, and birds given low-protein diets excreted less nitrogen. The activities of hepatic lipogenic and lipolytic enzymes were not different among the three dietary groups. 4. In Experiment 2, the dietary treatment did not affect growth performance or abdominal fat weight. Nitrogen excretion was significantly lower in chicks given the 150 g/kg CP diet than those on the 170 g/kg CP diet; however, nitrogen retention was no different among the treatments. Dietary CP and enzyme supplementation did not significantly affect hepatic enzyme activities. 5. These results suggest that CP content in the broiler diet can be reduced by 20 g/kg without lowering performance by the supplementation of crystalline amino acids, and can reduce nitrogen excretion by about 25%. Cellulase supplementation of a low-CP diet slightly lowered abdominal fat deposition; however, it did not significantly affect hepatic lipogenic and lipolytic enzyme activity.     

Comparison of the utilisation of palm kernel meal,brewers' dried grains and maize offal by broiler chicks

1. Palm kernel meal (PKM), brewers dried grains (BDG) and maize offal (MO) were included in broiler diets, each at 100, 150 or 200 g/kg; the diets were fed up to 35 d of age. 2. Overall food intake and weight gain decreased in the order BDG, PKM and MO. There were, however, significant interactions between the test ingredients and dietary concentrations in all the growth responses. Food intakes increased with the dietary concentrations of each test ingredient, but the increase was greater for BDG than PKM or MO. For weight gain, at 100 g/kg, the final body weights of the chicks fed on the diets with BDG and MO were similar, and those of chicks fed on the diet with PKM slightly lower. However, at 200 g/kg, growth rate of chicks fed on the BDG and PKM diets were similar while those of chicks fed on the MO diet was 7% lower. Efficiency of food utilisation was similar at 100 g/kg for all the ingredients and decreased as their concentrations increased; however, the decrease was considerably less for the PKM than for the MO and BDG diets. 3. Broilers fed on the BDG-based diets voided most excreta followed by those fed on the PKM and MO diets; excreta water content was highest from birds fed on the MO diets followed by the PKM and BDG diets. Apparent retention of dry matter was similar with all the test ingredients, but it decreased only significantly at 200 g/kg dietary concentration. The rate of passage was faster with the PKM diets followed by the MO and BDG diets; it was increased at 200 g/kg dietary concentration of the test ingredients.     

Effects of beta-glucanase-producing Lactobacillus strains on growth, dry matter and crude protein digestibilities and apparent metabolisable energy in broiler chickens

The effects of beta-glucanase expressed by transformed Lactobacillus strains on growth performance, apparent digestibilities of dry matter and crude protein, and apparent metabolisable energy were studied. Two hundred and forty 1-d-old chicks (Avian-43) were randomly divided into three dietary treatment groups and fed with the following diets: (i) basal diet (control) (BD); (ii) basal diet with parental Lactobacillus strains (BDP) and (iii) basal diet with transformed Lactobacillus strains (BDT). At 21 d of age, the body weight, body weight gain and feed conversion ratio of the BDT-fed chickens were significantly improved. At 14 and 21 d of age, the proportions of dry matter in the duodenum, jejunum, ileum, caeca and excreta of chickens given the BDT diet were significantly higher than those of chickens given the BD and BDP diets. Apparent metabolisable energy, digestibilities of crude protein and dry matter were also significantly improved (by 3.5, 5.6 and 3.5%, respectively) by the BDT diet. These results showed that the transformed Lactobacillus strains improved digestibility as well as enhanced the growth performance of chickens.     

Influence of the gut microflora on fasting heat production in chicks

1. The influence of the gut microflora on fasting heat production in chicks was investigated. 2. Single Comb White Leghorn chicks were fed on an adequate diet from 2 to 12 d of age and then fasted for 3 d. Fasting heat production was estimated from changes in body composition and energy content of droppings from days 1 to 3 of fasting. Measurements of body temperature and plasma thyroxine concentration were also made. 3. Body fat content was consistently higher in germ-free (GF) chicks than in conventional (CV) counterparts during the starvation period, whereas no difference was found in body protein content. The GF birds had a significantly higher body temperature than the CV controls with no change in plasma thyroxine concentration. 4. It was concluded that estimated fasting heat production of chicks was increased by the absence of the gut microflora.     

Note on the effects of protein concentration on responses to dietary lysine by chicks

1. This paper gives further analyses of data from previously reported trials in which chicks were fed diets with protein concentrations ranging from 140 to 280 g/kg diet, with the lysine content varied at each protein concentration. 2. Alternative methods of estimating the lysine requirement, at each concentration of protein, are investigated. 3. Although these methods produce rather different estimates of requirement, they do not change the conclusion that the lysine needed for maximum growth or maximum efficiency of food utilisation is a linear function of dietary protein concentration throughout the range from 140 to 280 g crude protein/kg. 4. It is concluded that lysine requirements for growing chicks should be specified as a proportion of the protein and not as a proportion of the diet.     

Relationship between food consumption and energy and nitrogen utilisation by chicks given varying amounts of standard and leucine-, isoleucine- and valine-deficient diets

The effect of different amounts of food, varying from below to above the rate of voluntary intake, was studied in chicks using a standard diet and diets containing only half the recommendation concentrations of leucine, isoleucine or valine. Irrespective of diet the body weight gain of the chicks increased with increasing food consumption. The body weight gain of chicks given the leucine-deficient diet was similar to that of chicks given the same amount of the standard diet. In contrast, the body weight gains of chicks given either the valine- or isoleucine-deficient diet were significantly less than that of chicks given the same amount of the standard diet. When the food intakes of the birds were similar the differences in body protein and water contents of the birds fed the different diets reflected differences in body weight gains, whereas body fat content was affected in the reverse manner. Retention and retention rate of dietary energy increased as food consumption increased. This was particularly evident in chicks given the isoleucine-deficient diet, followed by those given the valine-, leucine-deficient and standard diets. For all diets, the amounts of nitrogen retained and nitrogen retention rate (N retained/N consumed) increased in line with body weight gain. The metabolisable energy values of the diets were similar, except for the isoleucine-deficient diet which had a significantly higher metabolisable energy value than the standard valine-deficient diets.     

The effect of dietary energy and protein levels on production in breeding female ostriches

1. In a study spanning two breeding seasons, we assessed the effect of different dietary energy and protein levels on body mass, body condition, and egg production of female ostriches. 2. During the first breeding season, groups were given diets with energy concentrations of 8.5, 9.5 and 10.5 MJ/kg dry mass (DM) metabolisable energy (ME) and protein concentrations of 135, 150 and 165 g/kg. In the second breeding season, groups were given diets with ME of 7.5, 8.5 and 9.5 MJ/kg and protein contents of 105, 120 and 135 g/kg. 3. Body mass of birds on diets of 7.5 and 8.5 MJ/kg ME decreased significantly in the course of the breeding season compared with birds fed on diets with higher energy contents and body measurements decreased, suggesting a loss of body condition. 4. Females fed on diets containing only 7.5 MJ/kg ME produced significantly fewer eggs at significantly longer intervals, resulting in fewer chicks hatched. 5. There was no significant difference in egg mass, initial chick mass, chick survival to one month of age and body mass of chicks at one month. 6. Dietary protein concentrations had no effect on egg production, egg mass, hatchability, initial chick mass, chick survival or chick mass at one month old. 7. The female ostriches regained their original body mass during the 4-month rest period between breeding seasons, but significant differences in some parameters during the second breeding season suggest that they may not have fully recovered their body condition. 8. A dietary energy content of 7.5 MJ/kg proved to have an adverse effect on egg production by breeding female ostriches, and it may be concluded from this study that a diet containing 8.5 MJ ME/kg DM and 105 g/kg protein should be regarded as the minimum that can be used for breeding female ostriches without compromising egg production.     

Effect of L-carnitine supplementation on utilisation of energy and protein in broiler chicken fed different dietary fat levels.

Effects of a supplementation of 80 mg L-carnitine per kg diet were studied in broiler chicken at two dietary levels of fat (4 and 8%) and different feeding levels (ad libitum in a growth trial, 95 and 85% of ad libitum in a balance trial). A low-carnitine basal diet adequate in amino acid concentration was used. In the growth trial, each diet was fed to 9 groups of 10 birds each for 16 days from day 5 of live onwards. Growth and feed intake were determined. At the end of the trial, birds were killed and homogenised for subsequent empty body analysis. Accretion of protein and energy was determined using a representative blank group killed at the beginning of the trial. In the balance trial, 8 individual birds were used per treatment. Birds were offered the feed at approximately 85 and 95% of ad libitum intake, which was determined with separate birds for both fat levels. Excreta were quantitatively collected three times daily for 8 consecutive days beginning on day 17 individually for each bird. Supplemented L-carnitine did not significantly affect any response criterion. However, growth and feed conversion tended to be improved by about 5% in the carnitine supplemented diets when fed ad libitum. An interaction between carnitine and fat level occurred with regard to feed conversion, indicating that carnitine had a positive effect at the high fat level, but not at the low fat level. L-carnitine did not positively affect the metabolisability of energy (ME/GE) and the efficiency of energy utilisation (RE/GE or RE/ME). Similarly, no significant carnitine effect was determined with regard to N accretion and the efficiency of utilisation of dietary protein in both trials. It is concluded that endogenous carnitine synthesis is not the limiting factor for energy utilisation in broiler chicken, even at high dietary fat concentration. Occasionally reported positive effects of supplemental carnitine were likewise caused by reasons other than improved energy or protein utilisation. Further studies on amino acid utilisation and catabolism should consider marginal amino acid supply.     

Effects of protein concentration on responses to dietary tryptophan by chicks

1. Chicks were fed from 4 to 18 d on 40 diets containing all combinations of 8 crude protein (CP) concentrations (from 160 to 300 g/kg) and 5 tryptophan concentrations (from 7.5 to 13.5 g tryptophan/kg CP). 2. At each protein concentration there were responses in growth rate and in efficiency of food utilisation to supplementation with tryptophan. Curves were fitted to estimate the maximum response at each protein concentration. 3. The amounts of tryptophan required (g/kg) for maximum growth and maximum food efficiency were each linear functions of dietary protein concentration. The chick's requirement for tryptophan can be expressed as 12 g/kg CP. 4. It is concluded that a fixed ratio of tryptophan to protein should be specified in practical diet formulation, rather than a minimum dietary concentration of tryptophan.     

Comparison of broiler chicken performance when fed diets containing meals of Bollgard II hybrid cotton containing Cry-X gene (Cry1Ac and Cry2ab gene), parental line or commercial cotton

(1) Total and free gossypol contents were 6.2 and 0.8, 5.4 and 0.5, and 6.1 and 0.7 g/kg in meals processed (solvent extracted) from Bollgard (BG) II, non-BG II or commercial cottonseeds, respectively. (2) Broiler chicks were given one of 7 dietary treatments (iso-nitrogenous, 220 and 195 g crude protein/ kg diet at 0 to 21 and 21 to 42 d, respectively, at a metabolisable energy concentration of 12.15 MJ/kg). The treatments were: D1 (control, soybean meal [SBM] based), D2 and D3 (commercial CSM at 100 g/kg of diet with and without additional iron), D4 and D5 (BG II CSM with and without additional iron), and D6 and D7 (non-BG II parental CSM with or without additional iron). (3) Body weight gain, feed intake, feed conversion efficiency, nutrient utilisation, certain blood constituents and carcase traits were not significantly affected by dietary treatments. (4) Weights of bursa and thymus were significantly higher in groups given diets containing BG II or non-BG diets containing added iron. (5) The results suggest that low free gossypol content cottonseed meals, for example, BG II, non-BG II and commercial solvent-extracted CSM could be included at 100 g/kg in broiler diets, safely replacing soybean meal without additional iron.     

Dietary n-3 and n-6 fatty acids alter avian glucose metabolism

(1) This investigation studied the effects of dietary saturated and polyunsaturated fatty acids (PUFAs) from the n-3 and n-6 series on insulin action and glucose uptake in broiler chickens. (2) One-day-old male chicks were fed on a commercial starter diet for 3 weeks, randomly divided into three groups (n = 6) and fed ad libitum on isonitrogenous experimental diets of equal energy density for a further 6 weeks. The diets contained 20.8 g/100 g protein and 80 g/kg of either edible tallow, fish oil or sunflower oil, giving diets high in saturated fatty acids, n-S PUFAs or n-6 PUFAs, respectively. (3) Jugular catheterisation was performed under general anaesthesia during week 4 of the dietary treatments and the birds given 7 d post-surgery to recover. To estimate insulin action, a bolus glucose infusion (1 g/kg) was given to each chicken and sequential blood samples taken over a one-hour period. To estimate the disappearance rate of glucose from the plasma and its incorporation into tissues, 2-deoxy-D-3H glucose (2DG-3H glucose) was infused into each chicken (50 microCi) 2 d later. (4) Although there were no significant differences in glucose clearance rate following the glucose infusion, the maximal insulin release in response to the glucose infusion was higher in the tallow group than in either the n-3 or n-6 PUFA dietary groups. There were no significant differences in the clearance rate of 2DG-3H glucose. Labelled glucose incorporation into the breast muscle was greater in birds given fish oil than in birds given tallow and significantly greater than in birds given sunflower oil. (5) The data suggest that the type of dietary fat can influence glucose metabolism and that this change in glucose utilisation may alter the energy metabolism of the broiler.     

The use of growth and liver aspartate aminotransferase to assess the effect of source of non-essential nitrogen on pyridoxine depletion, repletion and requirements of chicks.

1. Two experiments were carried out to study the relationship between growth, liver aspartate aminotransferase (Asp AT) and dietary pyridoxine to determine the pyridoxine requirement of chicks fed on diets containing crystalline essential amino acids with glutamic acid (GA) or diammonium citrate (DAHC) as the non-essential nitrogen source. 2. In one experiment purified diets containing isolated soy-protein with 0 or 3 mg pyridoxine/kg were used. The deficient chicks were significantly lighter, coverted food less efficiently and liver Asp AT activity was decreased. When deficient chicks were offered an adequate diet performance improved and Asp AT activity rapidly increased. 3. In the second experiment diets containing crystalline amino acids GA or DAHC combined with 0, 1 or 3 mg pyridoxine/kg (GA: 0, GA: 1, GA: 3, DAHC: 1, DAHC:3) were used. Growth rates of chicks fed on GA: 1 and GA: 3 were similar, whereas chicks fed on DAHC: 1 were significantly lighter than those given DAHC: 3. The growth data indicated a pyridoxine requirement for chicks fed on the GA diets of not more than 1mg/kg and of more than 1 mg/kg in those fed on diets containing DAHC. Asp AT activity varied significantly with dietary content of pyridoxine but not with the nitrogen source. When Asp AT activity was used to assess pyridoxine requirements, there was nof difference between chicks fed on GA or DAHC diets.