S.P. Rose

Effects of dietary inclusion of plant extracts on the growth performance of male broiler chickens

were analysed using one-way ANOVA and means were separated by Tukey’s pairwise comparison. The birds fed on the probiotic-containing diets (T2 and T3) gained significantly more weight than that of birds fed on NC during young ages and the improvements were comparable with the birds fed on the diet containing the antibiotic growth promoter (Table 1). However the significant advantages were mainly confined only to the starter period with both probiotics and antibiotics. Nevertheless, all the treatment groups were numerically heavier than that of NC with varying degrees throughout the experiment though the differences were not statistically significant. Carcase yield or fat : meat ratio was not affected by any of the treatments (results not shown). There was no significant treatment effect on the Lactobacillus, Streptococcus or total microflora of the small intestine of the birds (Table 2). Results revealed that some commercial probiotics could be as effective as antimicrobial growth promoters in broilers, even with local diets under hot humid conditions in Sri Lanka. The authors gratefully acknowledge the Government of Sri Lanka for funding the project.

Chemical composition and the nutritive quality of different wheat cultivars for broiler chickens

1. Different wheat cultivar samples were grown in replicated trials on a single site in three harvest years. A total of 23 wheat samples were harvested. Nutritionally complete, meal-form diets that included each wheat sample at 650 g/kg were used to compare broiler growth performance and determine apparent metabolisable energy (AME). The relationships were examined between these variables of nutritive value for broilers and the chemical composition and tests of quality on the wheat samples. 2. The total starch contents of the wheat samples ranged from 594 to 732 g/kg dry matter (DM). The mean total non-starch polysaccharide (NSP) content was 100 g/kg DM comprising 73·5 g/kg DM of insoluble material. Endosperm hardness ranged between 10 and 77 relative units and Beaver was the softest cultivar in two of the batches of samples. The AME of the wheat-based diets had a maximum range of 0·5 MJ/kg within each of the three batches of wheat that were tested. 3. Endosperm hardness of the wheat grains, within a harvest year, was positively correlated with broiler weight gain and the 1000-grain weight was negatively correlated with feed conversion efficiency (FCE). Starch content and gross energy were positively correlated with determined AME, and DM, 1000-grain weight and water holding capacity were negatively correlated with AME. 4. A step-wise regression technique indicated that endosperm hardness and ash content of the wheat were the explanatory variables that, within harvest years, significantly reduced the unexplained variation in broiler growth rate, feed intake and FCE. The contents of total starch, crude protein and ether extract were the explanatory variables that, within harvest years, significantly reduced the unexplained variation in AME.

Effect of excess dietary sodium, potassium, calcium and phosphorus on excreta moisture of laying hens.

1. Four experiments were conducted to investigate the effects of dietary concentrations of sodium, potassium, calcium or phosphate on the water intake and excreta moisture of laying hens. A fifth experiment examined the effect on these variables of increasing amounts of 2 different sodium salts (chloride or bicarbonate) and the interactions with 2 levels of dietary phosphorus. 2. All experiments involved individually caged laying hens fed on diets varying in 1 or 2 minerals in replacement for washed sand. The experimental diets contained mineral concentrations that either met or exceeded the expected requirement of the hens. The diets were given for a 7 or 8 d feeding period and food and water intakes were measured and excreta were collected for the last 48 h of each feeding period. These data were corrected for evaporative water loss to the environment during the collection period. 3. Increasing dietary concentrations of sodium, potassium or phosphorus gave linear increases ( P <0.001) in the water intake of the laying hens and linear increases ( P <0.01) in the moisture content of their excreta. Each 1 g/kg increase in dietary mineral increased the moisture content of the excreta by 9.04 ( ± 1.57), 11.95 ( ± 2.02) and 5.59 ( ± 0.31) g/kg ( ± standard error) for sodium, potassium and phosphorus, respectively. Increasing concentrations of dietary calcium did not significantly affect the water intakes or excreta moisture levels of the laying hens. 4. The fifth experiment showed that, although there was a sodium × phosphorus interaction ( P <0.05), the effects of the 2 mineral additions were approximately additive. There were no significant differences ( P >0.05) in water intakes or excreta moisture contents due to the 2 different sodium salts (chloride or bicarbonate).

Effect of dietary protein concentrates on the incidence of subclinical necrotic enteritis and growth performance of broiler chickens

An experiment was conducted to quantify the effects of 3 nutritionally complete (similar protein and energy) corn-based diets that contained different dietary protein concentrates (potato-CP 76%, fish-CP 66%, or a mixture of soy proteins, soybean meal-CP 48%, and full-fat soy-CP 36%) on the incidence of spontaneously occurring subclinical necrotic enteritis (NE) in broiler chickens. A total of 1,260 birds were placed into 18 solid floor pens (70 birds per pen) and fed 1 of the 3 experimental diets from 15 to 31 d of age. The weight gains and feed intakes of the birds fed the potato- and fish-based diets were lower (P < 0.001) than those of the birds fed the soy-based diets. Weight gain:feed intake ratio and mortality rate were not affected (P > 0.05) by dietary treatment The birds fed the potato-based diets had a higher incidence of necrotic lesions in the duodenum (P < 0.001) and proximal jejunum (P < 0.01) than those fed the soy-based diets. The chickens fed the potato-based diet had a higher (P < 0.001) proportion of moderate to severe duodenal and distal ileal hemorrhages and liver lesions than the birds fed the soy-based diet. There was also a higher (P < 0.05) level of serum antibodies for Clostridium perfringens alpha toxin in birds fed the potato-based diet compared with the other 2 diets. The birds fed the fish-based diet had a similar (P > 0.05) incidence of subclinical NE in comparison to the birds fed the soy-based diet, although there was a higher incidence of intestinal hemorrhagic lesions. The differences in incidence of subclinical NE were not consistent with the relatively small differences in amino acid content between the diets or in the contents of nonstarch polysaccharides. However, the potato protein-based diet had higher trypsin inhibitor activity and a lower lipid content that could have contributed to the increased incidence of subclinical NE.

Shea nut ( Vitellaria paradoxa ) meal as a feed ingredient for poultry

Shea nut (Vitellaria paradoxa, Gaertner or Butyrospermum parkii, Kotschy) meal, a solid residue from the shea fat industry, is available in large quantities in West Africa. The meal is now receiving increased attention as a potential feed ingredient for poultry due to the increased amounts that are available due to high demand for shea fat in cosmetics and as a cocoa butter substitute in chocolate. Studies have shown nutrient compositions (g/kg dry matter basis) of crude protein (80–250), ether extract (17–362), crude fibre (53–138), ash (33–76) and nitrogen-free extract (318–675); probably with the major part of the variability being due to the amount of fat extraction, handling of the nuts prior to processing, or seasonal effects on nut production. Anti-nutritive factors reported include saponins (3.0-30.0 g/kg), tannins (98.7-156.4 g/kg) and theobromine (4.5 g/kg), which may have detrimental effects on performance of poultry. However, it has been shown that fermentation (i.e. wet incubation of a feedstuff) has the potential to reduce the negative effects of some of these anti-nutritive factors. It is evident that shea nut meal has low nutritive value; therefore it requires further improvements before it can become useful for the poultry feed industry.

The effect of changing the excreta moisture of caged laying hens on the excreta and microbial contamination of their egg shells

1. An experiment that included 1440 caged laying hens in 24 experimental units was conducted to determine the effect of differences in excreta moisture on the proportion of dirty eggs and the microbial contamination of eggs that were ostensibly uncontaminated by excreta. Excreta moisture contents were changed by giving the hens diets that contained 4 different concentrations of sodium. 2. Diets containing 1.6, 5, 10 or 15 g/kg dietary sodium were fed ad libitum to 1140 laying hens for a 12-week feeding period. A sample of excreta was collected from each experimental unit each week and its moisture content determined. All eggs produced were classified as clean or dirty according to the European Community Egg Marketing Regulations. A sample of eggs were collected from each experimental unit on 4 separate occasions in the last 4 weeks of the feeding period and the total bacterial numbers on ostensibly clean egg shells were determined. 3. Increasing dietary sodium concentration gave linear (P <0.01) increases in excreta moisture. Each 100 g/kg increase in excreta moisture increased (P <0.001) dirty egg numbers by 0.52% of the total eggs produced. Increasing excreta moisture gave a linear increase (P <0.001) in the (log-transformed) numbers of microorganisms that contaminated ostensibly clean egg shells.

A mixture of carvacrol, cinnamaldehyde, and capsicum oleoresin improves energy utilization and growth performance of broiler chickens fed maize-based diet

A total of 210, 1-d-old Ross 308 male broiler chickens were used in an experiment to investigate the effects of a supplementary mixture containing 5% carvacrol, 3% cinnamaldehyde, and 2% capsicum on dietary energy utilization and growth performance. The 2 diets were offered ad libitum to the chickens from 0 to 21 d of age. These included a maize-based control diet and the control diet with 100 g/t of supplementary plant extracts. Dietary apparent ME, N retention (NR), and fat digestibility (FD) coefficients were determined in the follow-up metabolism study between 21 and 24 d of age. Feeding the mixture of carvacrol, cinnamaldehyde, and capsicum increased weight gain by 14.5% (P = 0.009), improved feed efficiency by 9.8% (P = 0.055), and tended to increase (P = 0.062) carcass energy retention and reduce (P = 0.062) total heat loss compared with feeding the control diet. There was a 16.1% increase (P = 0.015) in carcass protein retention but no difference in carcass fat retention. Feeding plant extracts improved dietary FD by 2.1% (P = 0.013) but did not influence dietary NR. Supplementation of plant extract resulted in a 12.5% increase (P = 0.021) in dietary NE for production (NEp), while no changes in dietary ME were observed. The experiment showed that although dietary essential oils did not affect dietary ME, they caused an improvement in the utilization of energy for growth. Plant extracts may affect metabolic utilization of absorbed nutrients. Studies that have focused solely on the effect of plant extracts on ME alone may well have not detected their full nutritional value.

Effect of trypsin inhibitor activity in soya bean on growth performance, protein digestibility and incidence of sub-clinical necrotic enteritis in broiler chicken flocks

1. The effect of three different levels of dietary trypsin inhibitor activity (achieved by varying the amount of non-toasted full fat soya bean in replacement for toasted full fat soya bean) on the incidence of spontaneously-occurring sub-clinical necrotic enteritis (NE) in broiler chickens was compared. A fourth dietary treatment compared the effect of a diet that used potato protein concentrate as the major protein source. The determined trypsin inhibitor activity increased with the increasing content of non-toasted soya bean: 1·90, 6·21, 8·46 and 3·72 mg/g for the three soya bean diets (0, 100 and 200 g of non-toasted soya bean/kg) and the potato protein diet respectively. 2. Although increasing amounts of the non-toasted full-fat soya bean increased the feed intakes of the birds, there was a marked reduction in protein digestibility, weight gain and feed conversion efficiency. 3. There was a linear increase in sub-clinical NE lesions in the duodenum, jejunum, mid small intestine and ileum with increasing non-toasted soya bean. Caecal Clostridium perfringens counts increased with the increasing dietary content of non-toasted soya bean. Serum α-toxin antibodies were higher in the birds fed the 200 g non-toasted soya bean/kg diet compared with the other diets. 4. The results demonstrated that variation in the amount of non-toasted dietary soya bean not only affects growth performance of broilers but also affects the incidence of sub-clinical necrotic enteritis in the flock. Ensuring the lowest possible trypsin-inhibitor activity in soya bean samples is a valuable tool to improve the health and welfare of birds and in reducing the financial losses from this disease.

Ambient temperature and the egg laying characteristics of laying fowl

Laying hens have physiological responses that affect their productive performance when given different ambient temperatures. The objectives of this study were, first, to quantitatively describe the relationship between different constant environmental temperatures and egg production characteristics of laying hens by a statistical analysis and assessment of the published literature. Second, to compare the effect of different cycling environmental temperatures on the egg production characteristics of laying hens. Twenty-nine experiments were selected that had compared different constant temperatures and that included 21°C within their range. Differences in egg production were expressed as a proportion of the treatment group given 21°C within that experiment. An exponential curve with the addition of a linear trend gave the best (P<0.001) description of egg numbers, weight and mass, feed intakes and egg composition variables. There was a linear decrease (P<0.001) in measures of shell strength with increasing temperature. A second statistical analysis compared eight published experiments that had described the egg laying responses of laying hens kept in daily fluctuating temperatures and had been compared to a treatment group kept at 21°C within the same experiment. The results indicated that the egg laying responses of the hens were best predicted by computing the mean of the predicted responses to each of the temperatures that occurred during the day. However, information on the low temperature, the proportion of the day at the low temperature and the amplitude of the temperature cycle were required to give a precise prediction of the egg laying responses.

Dietary essential oils improve the hepatic antioxidative status of broiler chickens

Abstract 1. A total of 200 male Ross 308 chickens were used to evaluate the effects of a standardised combination of essential oils including 5% carvacrol, 3% cinnamaldehyde and 2% capsicum oleoresin (XT 6930; Pancosma S.A., Geneva, Switzerland) on their performance, hepatic antioxidant concentration and caecal tonsils morphometry. 2. Two diets were offered to broiler chickens from d old to 21 d of age. The control diet (C) was slightly lower in metabolisable energy (12.13 MJ/kg ME) and crude protein (215 g/kg CP) than breeders’ recommendation. The second diet, made as XT 6930, was added on the top of the control diet at 100 mg/kg. Each diet was offered ad libitum to birds housed in one of 10 floor pens in a randomised complete block design. The birds were housed in 20 floor pens, 10 birds in each pen, and were allocated to 10 replicates of the two dietary treatments. 3. The concentration of antioxidants in the liver of the birds was determined using high-performance liquid chromatography (HPLC) at 21 d of age. Birds fed control diet only had lower weight and converted less efficiently feed to gain compared to birds fed essential oils-supplemented diet. Feed consumption was not affected by dietary treatments. The antioxidant data showed that supplemented essential oils improved the hepatic concentration of carotenoids and coenzyme Q10 when fed to broiler chickens. The morphometry of the caecal tonsils of the birds was not influenced by dietary treatments. 4. It can be concluded that that dietary combination of essential oils, including carvacrol, cinnamaldehyde and capsicum oleoresin, improved growth, feed efficiency and the hepatic concentration of carotenoids and coenzyme Q10 when fed to broiler chickens.