Yield and composition of raw and cooked meat of small white turkeys as influenced by dietary nutrient density and energy to protein ratio

1. Raw and cooked meat yields and the dry matter and fat contents of meat samples were determined on 144 carcases of Small White turkeys fed on diets that varied in nutrient density (ND) and energy to protein ratio (E:P).

2. High ND diets increased body weights, eviscerated carcase weights, relative carcase yields and carcase skin yield, but not breast or total meat yields.

3. Feeding a low ND diet to 6 weeks followed by diets with progressively increasing ND yielded performance and carcases with qualities comparable to feeding diets of constant medium or high ND; consequently cost savings could be made.

4. Increasing E:Ps reduced body weights, eviscerated carcase weights and carcase yields. Breast and total meat yields from male but not female carcases, and skin yield of female but not male carcases decreased with higher E:Ps.

5. The fat contents of breast and thigh meat samples increased with ND. The fat content of breast but not thigh meat decreased with higher E:P. Dry matter contents of meat samples did not vary consistently with changes in fat content.     

Absorption of carbohydrate-derived nutrients in sows as influenced by types and contents of dietary fiber

The current investigation was undertaken to study the absorption and plasma concentration of carbohydrate-derived nutrients [glucose, short-chain fatty acids (SCFA), and lactate] and the apparent insulin production in sows fed diets containing contrasting types and contents of dietary fiber. Six sows were fed 3 experimental diets, low fiber (LF; 177 g of dietary fiber and 44 g of soluble fiber/kg of DM), high soluble fiber (HF-S; 429 g of dietary fiber and 111 g of soluble fiber/kg of DM), and high insoluble fiber (HF-I; 455 g of dietary fiber and 74 g of soluble fiber/kg of DM), in a repeated crossover design. Variations in dietary concentration and solubility of dietary fiber were obtained by substituting starch-rich wheat and barley in the LF diet with dietary fiber-rich co-products (sugar beet pulp, potato pulp, pectin residue, brewers spent grain, pea hulls, and seed residue, which have distinct physicochemical properties). The main carbohydrate component of the LF diet was starch and nonstarch polysaccharides (cellulose and noncellulosic polysaccharides) for the 2 high dietary fiber diets. Consumption of the LF diet resulted in increased and rapid glucose absorption at 0 to 4 h postfeeding. With the HF-I diet, the glucose absorption pattern was similar but at a decreased rate, whereas it was decreased and delayed with the HF-S diet (diet, P < 0.001; time, P < 0.001). These differences were also reflected in the insulin response. The quantitative absorption of SCFA at 0 to 10 h postfeeding was greater when feeding the HF-S diet compared with the LF diet (P < 0.001) and intermediate when feeding the HF-I diet (P < 0.001). The study showed that feeding the high dietary fiber diets resulted in a increased and more uniform uptake of SCFA than when feeding the LF control. Moreover, the HF-S diet reduced diurnal variation in glucose and insulin concentrations.     

Digestibility of phosphorus in growing pigs as influenced by source and concentration of dietary phosphorus and collection site

The current study examined the influence of source and concentration of dietary phosphorus (P) on the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of P in growing pigs. Eighteen cannulated barrows (25 ± 5 kg) were allotted to a triplicate 6 × 3 incomplete Latin square design with six diets and three periods. The diets comprised of soybean meal (SBM) or distillers' dried grain with solubles ( DDGS) as sole sources of dietary P, and three concentrations of P (2.0, 2.5 or 3.0 g/kg) in a 2 × 3 factorial arrangement. The AID and ATTD of P were not different (p = 0.37) in all diets. Apparent digestibility of P was affected (p < 0.01) by source and concentration of P. There was no interaction between source and concentration of dietary P on the apparent digestibility of P. Determined by regression analysis, the true ileal digestibility of P was 58.3% or 57.6%, and true total tract digestibility of P was 56.0% or 62.6%, for SBM or DDGS, respectively. The regression-derived ileal endogenous P loss (EPL) was 0.61 or 0.13 g/kg DM intake, and total tract EPL was 0.53 or 0.35 g/kg DM intake, for SBM or DDGS, respectively. In conclusion, the study demonstrated that both the source and concentration of dietary P affect the digestibility of P in growing pigs.     

Plasma alkaline phosphatase and production traits in laying hens as influenced by dietary protein,strain and age

1. Plasma alkaline phosphatase (ALP) activity was determined in 4 laying strains (White Leghorn, New Hampshire, Native Brown and Native Barred) at 48 and 54 weeks of age. Birds were fed 1 of 2 isoenergetic diets with calculated crude protein contents of 152 and 181 g/kg. 2. No significant differences in plasma ALP activity were noted between the strains, although significant differences in laying performance between strains were evident. 3. There was no response in plasma ALP activity to the high dietary protein level in any strain. Depressed plasma ALP activity was associated with increasing age of birds. 4. The results failed to confirm the suggestion that ALP activity is related to egg production of the laying hen.     

Unexpected consequences of genetic selection in broilers and turkeys: problems and solutions

1. Genetic theory leads to the expectation that unexpected consequences of genetic selection for production traits will inevitably occur and that these changes are likely to be undesirable.

2. Both artificial selection for production efficiency and “natural” selection for adaptation to the production environment result in selection sweeps that increase the frequencies of rare recessive alleles that have a negative effect on fitness.

3. Fitness is broadly defined as any trait that affects the ability to survive, reproduce and contribute to the next generation, such as musculoskeletal disease in growing broiler chickens and multiple ovulation in adult broiler parents.

4. Welfare concerns about the negative effects of genetic selection on bird welfare are sometimes exaggerated but are nevertheless real. Breeders have paid increasing attention to these traits over several decades and have demonstrated improvement in pedigree flocks. There is an urgent need to monitor changes in commercial flocks to ensure that genetic change is accompanied by improvements in that target population.

5. New technologies for trait measurement, whole genome selection and targeted genetic modification hold out the promise of efficient and rapid improvement of welfare traits in future breeding of broiler chickens and turkeys. The potential of targeted genetic modification for enhancing welfare traits is considerable, but the goal of achieving public acceptability for the progeny of transgenic poultry will be politically challenging.     

Histopathologic and bacteriologic evaluations of cellulitis detected in legs and caudal abdominal regions of turkeys

The objective of this study was to identify the causative agent of cellulitis in turkeys. Eighteen flocks from nine producers were sampled at the local processing plant, and 37 birds with cellulitis on legs or caudal thoracic area were obtained. None of the 37 birds with cellulitis had lesions in other organs. On gross examination, lesions were categorized into two groups: cellulitis with unopened skin lesions (type a) and cellulitis with opened skin lesions (type b). Histopathologically, cellulitis with unopened skin lesions had dermal necrosis with underlying fibrin and inflammatory exudate but cellulitis with open skin lesions had chronic granulomatous/granulation tissue-type reaction associated with foreign material. A complete bacteriologic study was conducted on 25 of 37 birds. Bacteria were isolated from 12 of the 25 birds with cellulitis lesions. No aerobic, microaerophilic, or anaerobic bacteria were isolated from the remaining 13 birds with cellulitis lesions. Escherichia coli was isolated in low numbers in mixed cultures with Proteus mirabilis, Lactobacillus spp., Klebsiella spp., and Staphylococcus spp. in 9 of 12 lesions. The remaining few cases yielded P. mirabilis in pure culture or in mixed culture with Pseudomonas aeruginosa. Types a and b cellulitis lesions in turkeys could be associated with primary contact dermatitis and skin abrasions, respectively. Their occurrence is likely associated with different management practices.     

Estimation of accuracy and bias in genetic evaluations with genetic groups using sampling

Accuracy and bias of EBV are important measures of the quality of genetic evaluations. A sampling method that accounts for the uncertainty in the estimation of genetic group effects was used to calculate accuracy and bias of estimated effects. The method works by repeatedly simulating phenotypes for multiple traits for a defined data and pedigree structure. These simulated values are analyzed using BLUP with genetic groups in the relationship matrix. Accuracies and biases are then calculated as correlations among and differences between true and estimated values across all replicates, respectively. The method was applied to the Irish beef production data set for 15 traits and with 15 genetic groups to account for differences in breed means. Accuracy and bias of estimated genetic group effects, estimated comparisons between genetic group effects, EBV within genetic group, and EBV across genetic group were calculated. Small biases were detected for most estimated genetic group effects and most estimated comparisons between genetic group effects. Most of these were not important relative to the phenotypic SD of the traits involved. For example, a bias of 0.78% of the phenotypic SD was detected for carcass conformation in Aberdeen Angus. However, one trait, calf quality, which had few performance records in the data set, displayed larger bias, ranging from -10.31 to 5.85% of the phenotypic SD across the different estimated genetic group effects. Large differences were observed in the accuracies of genetic group effects, ranging from 0.02 for feed intake in Holstein, which had no data recorded, to >0.97 for carcass conformation, a trait with large amounts of data recorded in the different genetic groups. Large differences were also observed in the accuracies of the comparisons among genetic group effects. The accuracies of the EBV within genetic group and EBV across genetic group were sometimes different; for example, carcass conformation in Belgian Blue had an average accuracy within genetic group of 0.69 compared with an average accuracy across genetic group of 0.89. This suggests that the accuracy of genetic groups should be taken into account when publishing EBV across genetic groups.