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.     

Skeletal changes in broiler chicks and turkey poults fed diets containing ochratoxin A

Broiler chicks and turkey poults were divided at hatching into experimental and control groups. Experimental birds were fed a diet contaminated with 4 ppm ochratoxin A, whereas the ration of control birds was confirmed to be mycotoxin free. Birds were killed at fortnightly intervals up to 10 weeks old and skeletal changes were investigated. Almost all experimental birds developed generalised skeletal osteopenia with disturbed endochondral and intramembranous bone formation. Histological changes in diaphyseal cortices could account for the reduced breaking strength of bones from birds fed mycotoxin, which have been reported by others. One bird showed changes consistent with a diagnosis of hypophosphataemic rickets. In others, however, osteoid formation was defective and changes were interpreted as osteoporosis. Although it might be tempting to suggest that osteoporosis is a result of a direct toxic effect of ochratoxin on osteoblasts, the effect of inanition, inactivity and general debility may be equally important.     

Energy and protein utilisation by broiler chickens fed diets containing cottonseed meal and supplemented with a composite enzyme product

ABSTRACT

1. The present study examined the potential of new-generation microbial enzymes to improve the utilisation of energy and protein of cottonseed meal (CSM)-containing diets, with the aim of increasing its inclusion level in broiler chickens diets.

2. Four hundred and eighty, one-day-old Ross 308 male broilers were used to assess the utilisation of energy and protein by broiler chickens fed diets containing four graded levels of CSM – none, low (4, 8, 12%), medium (5, 10, 15%) or high (6, 12, 18%) in the starter, grower, and finisher phases, respectively, supplemented with 100 mg/kg of a composite enzyme product (xylanase and β-glucanase).

3. Inclusion of CSM improved (P < 0.01) apparent metabolisable energy (AME), with further improvement (P < 0.001) seen in the enzyme-supplemented diets. Inclusion of CSM reduced (P = 0.002) the metabolisable energy intake (MEI), but this was increased (P < 0.05) with enzyme supplementation.

4. Enzyme addition increased (P < 0.001) the net energy of production (NEp), while heat production (HP) decreased (P < 0.001) with CSM inclusion. More energy was retained as fat (P < 0.05) and protein in birds fed diets with the enzyme, but this was reduced (P < 0.029) by CSM.

5. There was an increase (P < 0.05) in efficiencies of ME use for energy, lipid and protein retention, with higher CSM levels. The enzyme improved (P < 0.013) efficiency of ME use for lipid retention.

6. Feeding diets containing CSM to the broilers enhanced (P < 0.05) protein intake (PI) and protein efficiency ratio (PER). Positive effects (P < 0.05) of enzyme were observed on protein gain (PG) and net protein utilisation (NPU).

7. Results obtained from this study suggested that nutrient utilisation of diets containing CSM by broiler chickens can be improved by enzyme supplementation.     

Zinc deficiency in pheasant chicks fed practical diets

A disease syndrome characterized by abnormal feathering and varus deviation of the tarsometatarsus spontaneously occurred in pheasant chicks fed a practical commercially prepared diet. The addition of supplemental Zn to the commercial diet was effective in alleviating the clinical signs, even though the commercial mix had Zn levels that met the published pheasant chick requirement. Supplemental arginine was ineffective in reducing the severity of the clinical signs. Also, when the diet was mixed in a laboratory setting, pheasant chicks did not develop abnormal feathering and leg bones. Clinical signs caused by feeding the commercial mix were not reproduced by altering dietary calcium and phosphorus levels in the laboratory mix. Neither adding a pellet binder nor removing supplemental Zn from the lab mix produced as severe leg and feather deformities as the commercial mix. Thus, unidentified dietary factors are capable of causing a Zn-deficiency syndrome in pheasant chicks fed practical diets with analyzed Zn levels meeting the required levels.     

Effects of dietary cholestyramine on the utilisation of diets containing medium or long chain triacylglycerols by chicks

1. The effects of graded dietary concentrations of cholestyramine (CSTY, a bile acid binding polymer), which prevents micelle formation and bile acid reabsorption, on the lipid and energy metabolism of chicks given diets containing different dietary concentrations of medium chain triacylglycerol (MCT) and long chain triacylglycerol (LCT) were investigated.

2. MCT‐ or LCT‐supplemented diets containing 100 or 200 g oil/kg diet and 0, 10 or 20 g CSTY kg were fed to 7 d old chicks for 10 d. As dietary CSTY concentration increased, a reduction in the metabolisable energy value was observed for both dietary lipid sources. Consequently, fat and energy retentions were also reduced as the dietary CSTY content increased.     

Effect of dietary calcium level and source on mineral utilisation by piglets fed diets containing exogenous phytase

Calcium and phosphorus are essential minerals, closely linked in digestive processes and metabolism. With widespread use of low P diets containing exogenous phytase, the optimal dietary Ca level was verified. The 40‐day study evaluated the effects of Ca level (4, 7 and 10 g/kg diet) and Ca source (Ca from CaCO₃ and from Lithothamnium calcareum) on mineral utilisation in 72 piglets (7.9 ± 1.0 kg BW) fed an exogenous phytase containing diet with 2.9 g digestible P/kg. Measured parameters were growth performance, stomach mineral solubility, bone breaking strength and urinary, serum and bone mineral concentration. The apparent total tract digestibility of minerals was also assessed in the two diets with 7 g Ca/kg, using 12 additional pigs. Regardless of Ca source, increasing dietary Ca impaired feed conversion ratio, increased urinary pH, increased serum and urinary Ca, decreased serum and urinary P, decreased serum Mg and increased urinary Mg, increased serum AP activity, decreased bone Mg increased bone Zn. Bone breaking strength was improved with 7 compared to 4 g Ca/kg. Compared to CaCO₃, Ca from Lithothamnium calcareum increased serum Mg and with, 10 g Ca/kg, it limited body weight gain. The dose response of Ca in a diet with 2.9 g digestible P/kg and including exogenous phytase indicated that: (i) a low dietary Ca was beneficial for piglet growth, but was limiting the metabolic use of P; (ii) a high dietary Ca level impaired P utilisation; (iii) the optimal P utilisation and bone breaking strength was obtained with a dietary Ca‐to‐digestible P ratio of 2.1 to 2.4:1; (iv). Increasing dietary Ca reduced Mg utilisation, but not Zn status, when fed at adequate level. Finally, Ca from Lithothamnium calcareum had similar effects on Ca and P metabolism as CaCO₃, but impaired growth when fed at the highest inclusion level.     

Calcium and phosphorus utilisation in chickens fed on diets high in N-alkane-grown yeast

Interactions between calcium (Ca) and phosphorus (P) were studied in young chickens fed on diets high in n-alkane-grown yeast and in chicks fed on control soya-fishmeal diets for 14 d. Additions of inorganic Ca to diets containing 300 g yeast/kg caused increases in body-weight gain, gain:food ratio and bone mineralisation up to a total dietary concentration of 13.9 g Ca/kg. At all additions of Ca, bone mineralisation was inferior in yeast-fed chicks compared with control chicks. Supplementation of high Ca diets (16.8 g Ca/kg) with inorganic P led to further improvements in body-weight gain, food intake and food utilisation of chicks fed on high-yeast diets. Bone mineralisation also improved but was always inferior in the yeast-fed chicks compared with control chicks. It was concluded that Ca and P supplementation was necessary in high-yeast diets due to low dietary Ca concentrations and low availability.     

Effects of additional zinc and phytase on zinc availability in piglets and chicks fed diets containing different amounts of phytates

Two maize based diets containing 2.3 g phytic P and 38 mg Zn/kg (P+) or 1.3 g phytic P and 25 mg Zn/kg (P−) were formulated. A third diet (P+/Phytase) was P+ supplemented with 3-phytase (500 FTU/kg). Each of these three basal diets, supplemented or not with 15 mg Zn/kg, was given during 20 days to weaned piglets and to 1-day-old chicks. Chicks fed the P− diets were removed from the data set because of an abnormally low feed intake.

In piglets, added Zn increased bone (P < 0.05) and plasma Zn (P < 0.01) irrespective of the basal diet (basal diet × Zn, P > 0.05). Supplementing P+ with phytase was more efficient in improving these indicators of Zn status than replacing P+ by P−. In chicks, supplemental Zn improved Zn status in a higher extent when added to P+ than to P+/Phytase (basal diet × Zn, P < 0.05). Phytase increased Zn status in a lesser extent than 15 ppm supplemental Zn. More Zn was soluble in gizzard than in stomach which corresponded to the differences in pH (4.2 vs 5.0). Phytase increased soluble Zn in stomach (P < 0.05) but not in gizzard. These results suggest a higher availability of Zn in chicks than in piglets in the absence of phytase. This may explain the higher efficacy of phytase for improved Zn availability in piglets than in chicks.     

Zinc, copper and iron utilisation by chicks fed various concentrations of zinc

1. Zinc, iron and copper interactions were examined in chicks (New Hampshire X Single Comb White Leghorn) grown individually in stainless steel cages and fed on purified diets with three concentrations of zinc: control (37 mg Zn/kg), moderate (100 mg Zn/kg) and excess (2000 mg Zn/kg) in three studies. 2. Chicks given either moderate or excess zinc excreted more than twice as much 65Zn from a test diet as those fed on the control diet. Thus chicks given the moderate amount of zinc had concentrations of zinc in tissues similar to those of controls but chicks given excess zinc accumulated zinc in their tissues. 3. The specific activity of 65Zn in the tissues, especially in the bursa of Fabricius, of chicks given excess zinc was not reduced as much as would be predicted. Thus, ingestion of excess zinc appeared to reduce tissue turnover of 65Zn, especially in the bursa. However, humoral immune responses, as measured by antibody titres to sheep red blood cells, were not affected. 4. Chicks given excess zinc or pair-fed on the control diet retained less 59Fe from a test diet than chicks given control or moderate concentrations of zinc ad libitum. The iron concentrations in tibiae of chicks given excess zinc were depressed.     

Enzyme studies with the livers of chicks fed semi‐synthetic diets containing crystalline amino acids and diammonium citrate

The levels of glutamate dehydrogenase [NAD(P)], (GDH), aspartate trans‐aminase (AspT) and alanine transaminase (AlT) were measured in livers from chicks fed on a semi‐synthetic diet containing crystalline essential amino acids as the sole nitrogen source (diet A). The effects of a supplement of 12.0% glutamic acid (diet H) or 11.07% diammonium citrate (DAC) (diet B) or 12.0% glutamic acid plus 1.0% proline with an additional 0.6% glycine (diet C) on these enzymes were studied and the results compared with the levels found for control chicks given a typical diet based on cereal protein (diet J). The abilities of livers from chicks given diets A, B and C to synthesise [14C] glutamic acid from [14C]2‐oxoglutaric acid and diammonium citrate (DAC) were assessed.

The levels of GDH, AspT and AlT found in the livers of chicks given the control diet were 54.1, 966 and 123.7 units/mg protein respectively. Non‐essential nitrogen added as glutamic acid or as DAC did not cause induction of the enzymes studied above control levels. Glutamic acid (diets H and B) caused a depression of GDH levels (37.4 and 38.9 units/mg protein respectively) but had no effect on AspT and AlT compared with the controls, whereas DAC caused a decrease in AlT (43.9 units/mg protein) but had no effect on AspT and GDH; diet A depressed AlT and AspT levels (64.4 and 735 units/mg protein respectively).

The livers of chicks given diets A, C and B varied in their ability to synthesise glutamic acid, 39.3%, 31.9% and 24.0% respectively of the radioactivity being recovered as glutamic acid.     

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.     

Performance of broiler chicks fed on diets containing urea ammoniated neem (Azadirachta indica) kernel cake.

1. The performance, nutrient utilisation, blood profile, carcase composition, gross pathology and sensory evaluation of meat from broiler chicks fed from 3 to 42 d on diets containing urea ammoniated neem (Azadirachta indica, A.juss) kernel cake (NKC) as a protein supplement to replace peanut meal (PNM), were evaluated. NKC was ammoniated with urea at 15 (UANKC 1) or 25 g (UANKC 2)/kg and incorporated into the test diets to replace either half (134.5 g/kg (L-UANKC 1) and 127.5 g/kg (L-UANKC 2), respectively) or all (269, g/kg (H-UANKC 1) and 255.0 g/kg (H-UANKC 2), respectively) of the nitrogen provided by the PNM. 2. The growth, food intake and efficiency of nutrient utilisation of the birds were comparable between the reference and L-UANKC 1 and 2 diets but were depressed on the other UANKC diets. 3. The retention of dry matter (DM), crude fibre (CF), nitrogen-free extract, total carbohydrate, gross energy, acid detergent fibre, calcium and phosphorus were similar among groups, except lower DM and higher CF and phosphorus retentions were noted in chicks fed on the H-UANKC 1, H-UANKC 2 and L-UANKC 2 diets. All the chicks were in positive nitrogen balance and percentage nitrogen retention did not differ between the reference and test diets. 4. Haemoglobin, total erythrocyte count and aspartate amino transferase activity were unaffected by diet, but total leucocyte count was higher in chicks fed on the H-UANKC 1 and 2 diets and alanine amino transferase activities were lower in chicks fed on the test diets. Blood urea increased as the amount of urea in the diets increased. 5. Most of the physico-chemical carcase characteristics from birds fed on the L-UANKC 2 were comparable to those from birds fed on the reference diet. No bitter taste was noticed in cooked meat from any diet by the sensory panel. 6. Incorporation of L-UANKC 2 was economical and responses were comparable to those observed on the reference diet. 7. It was concluded that NKC detoxified with 25 g urea/kg can economically and successfully replace half the nitrogen of PNM in broiler diets thereby mitigating the chronic shortage of costly oil cakes in developing countries.     

Immunocompetence of fattening pigs fed organic versus conventional diets in organic versus conventional housing

The effect of organic or conventional feeding on the immune response of pigs was determined using organic or conventional housing in a pig fattening unit. The experimental design involved four pens of four animals per housing and diet combination (organic housing and organic nutrition; organic housing and conventional nutrition; conventional housing and organic nutrition and conventional housing and conventional nutrition). The IgM, IgA and IgG responses against intramuscularly injected bovine thyroglobulin were determined as indicators of the antigen-specific immune responsiveness. Some general health and welfare related parameters were evaluated by measuring haptoglobin concentrations at selected times; blood lactate concentration was measured at slaughter. Conventional housing led to a higher IgG response three weeks after the first immunisation. Organic housing led to lower haptoglobin and lactate concentrations at slaughter, indicating a higher stress resistance in these pigs. No major differences between the two feeding types were found. We conclude that the immune responses following either a conventional or an organic diet are comparable, whereas organic housing can increase stress resistance at slaughter compared to conventional housing.     

Toxicity and tissue accumulation of copper in chicks fed casein and soy-based diets.

Experiments were conducted to study Cu toxicity in chicks fed casein or soy-containing diets containing graded levels of excess CuSO4.5H2O. Differences between diets in measures of Cu toxicity were pronounced. Addition of 800 mg of Cu/kg to a casein-dextrose semipurified diet decreased weight gains by 63%, but the same addition of Cu to a corn-soybean meal complex diet decreased gains by only 8%. At all levels of Cu supplementation (100, 200, 400 or 800 mg/kg), Cu deposition in the liver was increased markedly in chicks fed casein diets compared with those fed the complex diet. Substituting soy-protein concentrate for casein in the semipurified diet resulted in a marked decrease in Cu toxicity as measured by weight gain reductions and tissue accumulation of Cu.     

Caecal microbiota of chickens fed diets containing propolis

The present study aimed to evaluate the effect of different levels of ethanolic extract of propolis (EEP) and raw propolis (RP) on broiler performance and on selected bacterial groups in caecal microbiota using fluorescent in situ hybridization (FISH) measured by fluorescent activated cell sorting. Two experiments were conducted with 120 male chicks from 1 to 21 days of age for each, raised in cages and distributed in a completely randomized experimental design; there were five replicates with four birds per experimental unit and six treatments for each experiment (trial 1 – EEP – 0, 1000, 2000, 3000, 4000 and 5000 ppm and trial 2 – RP – 0, 100, 200, 300, 400 and 500 ppm). Fluorescent probes were used against the bacterial groups in caecal samples collected at 21 days of age. The data were subjected to one‐way anova followed by Tukey's and regression analyses were used to assess the relationship between dietary levels of EEP or RP on performance and intestinal microbiota (p < 0.05). In the trial 1, results showed that the EEP did not cause any significant (p > 0.05) modification in the performance and caecal microbiota. In the trial 2, RP inclusion did not affect the performance but changed the bacterial composition (p < 0.05). Clostridiaceae, Gammaproteobacteria excluding Enterobacteriaceae and Lactobacillus spp. showed a quadratic response (p < 0.05), with the lowest value predicted to occur at 240 ppm, 221 ppm and 213 ppm of RP respectively. The proportion of Bacteroidaceae and Gammaproteobacteria did not differ (p > 0.05) among the experimental groups. The inclusion of ethanolic extract of propolis did not affect the performance and intestinal microbiota, whereas the supplementation of raw propolis modulates the caecal microbiota composition without any effects on chicken performance.     

Energy utilisation of carbohydrate, fat and protein sources in newly hatched broiler chicks

1. TME, TMEn and metabolisability (TME/gross energy) of energy-yielding foodstuffs were determined in 1, 3 and 10 d old broiler chicks, using the assay method developed by Murakami et al. (1994), in order to characterise energy utilisation during the 10 d after hatching. 2. TME, TMEn and metabolisability of dextrin and starch were low in chicks aged 1 d, and increased with age up to 10 d. Energy values of glucose and maltose at days 1 and 3 could not be determined because of the sudden death of birds soon after the feeding. TMEn and metabolisability of cereal sources were lower in d-old chicks than in those aged 3 and 10 d. At all ages, maize was better utilised than wheat and sorghum. 3. In the fat sources (coconut oil, beef tallow and safflower oil) no age dependency was observed in TME, TMEn and metabolisability. 4. Bioavailability of soyabean meal and fish meal was lower at 1 d than at 3 d and 10 d. Energy utilisation from casein was the highest among the protein sources tested and it was not age dependent. 5. It is concluded that energy utilisation of carbohydrate and protein sources during 10 d post-hatch tended to increase with age. Among the energy yielding foodstuffs fat sources seem to be better utilised, with no age dependency.     

Nutrient digestibility in sheep fed diets containing Roundup Ready or conventional fodder beet, sugar beet, and beet pulp

The objective of this digestibility assessment was to determine whether there are significant differences in the digestibility of Roundup Ready (glyphosate-tolerant) and conventional sugar beet, fodder beet, and beet pulp produced from sugar beet varieties when fed to sheep (seven wethers per treatment group). Three experiments were conducted in this assessment. Experiment 1 (35 wethers) compared one glyphosate-tolerant fodder beet variety with four conventional varieties, Exp. 2 (42 wethers) compared one glyphosate-tolerant sugar beet variety with five conventional varieties, and Exp. 3 (42 wethers) compared beet pulp derived from glyphosate-tolerant sugar beet with beet pulp from five European locations. The experimental phase consisted of a 2-wk preliminary period followed by a 1-wk collection period for Exp. 1 and 2, and a 1-wk preliminary period followed by a 1-wk digestibility collection period for Exp. 3. Diets were comprised of grass hay at 30, 30, and 20% of DM for Exp. 1, 2, and 3, respectively, with the balance being beet components. Urea and sodium sulfate were supplemented (8 and 2.9 g, respectively, for Exp. 1 and 2; and 6 g and 2.16 g, respectively, for Exp. 3) to supply sufficient dietary N and S. Each diet was fed to sheep (96 +/- 0.9 kg) in the three experiments to at or near maintenance energy levels. Treatment differences were considered significant at P < 0.05. Apparent digestibilities of DM, OM, CP, NDF, ADF, and DE for glyphosate-tolerant fodder and sugar beets did not differ from those for commercial fodder and sugar beets in Exp. 1 and 2. There were differences (P < 0.05) in DM, OM, CP, NDF, ADF, and DE digestibilities influenced by the different varieties of beet pulp in Exp. 3, but these were not unique to just the Roundup Ready sugar beet variety. Digestibilities and feeding values of Roundup Ready fodder beet, sugar beet, and beet pulp produced from Roundup Ready sugar beet varieties were not influenced by the introduction of the Roundup Ready trait compared with conventional varieties.     

Breed and sex differences in the growth rates of chicks fed diets supplemented with penicillin

Nine hundred and forty‐seven chicks comprising 490 chicks of heavy type and 457 chicks of light type laying breeds were reared in a series of experiments. Approximately one‐half was fed on a basal ration and the other on this ration plus 55 mg of procaine penicillin per kg of food. An additional 120 chicks, equal numbers of both sexes of both types, were reared on the above‐mentioned rations and half were killed at 3 weeks of age and the other half at 9 weeks so that their intestines could be studied at post‐mortem examination.

The male chicks fed the antibiotic grew at a significantly faster rate than the females up to 3 weeks of age, and the weights of 1 cm lengths of the small intestine were significantly reduced by the antibiotic in the male chicks at 9 weeks of age. Type responses were not clearly defined, but there was a significant reduction in the weight of 1 cm lengths of the small intestine at 9 weeks of age in the heavy type chicks when compared with the light type.