Optimum mating systems for the myostatin locus in cattle

Inactive myostatin (one or two copies) results in increased muscularity, increased yield of closely trimmed retail product, reduced fat content, increased lean growth efficiency, reduced quality grade, increased birth weight, and increased dystocia. Even though one or two copies of inactive myostatin reduces quality grade or marbling compared to zero copies, there is no decrease in meat tenderness. It may be possible to use mating systems to make the most of the advantages of inactive myostatin while minimizing the disadvantages. The objective of this study was to develop a method to compare mating systems among genotypes at the myostatin locus. Economic variables that influence the profitability of alternative mating systems are prices per unit of retail product for USDA quality grades Standard, Select, and Choice; cost of an assisted calving; and cost of genotyping. Because of variation in both economic variables and biological parameters, a single mating system is not expected to universally maximize profit. We identified seven mating systems that each yield maximum profit for different combinations of values for biological parameters and economic variables. Use of inactive myostatin was profitable as long as the price for Select was at least 80% of the Choice price and the price for Standard at least 60%. As the price for Select and Standard increase up to the Choice price, mating systems that produce a higher proportion of inactive myostatin alleles become more profitable. Profitable use of inactive myostatin depends either on retaining ownership of beef until it is fabricated into retail product or the development of specialty markets that place greater value on lean yield and less on marbling, unlike conventional U. S. markets.     

Model calculations on the economic efficiency of sheep production

The answers to the questionnaire by the Commission on Sheep and Goat Production show quite large differences in the price relationships, particularly between meat and wool.It is at first shown from model calculations, how the optimum duration of using the ewes changes with a change of the relationship between mutton price and lamb meat price. In all cases, in which mutton is very cheap in comparison with lamb meat, a longer utility period is generally more efficient than a shorter one and vice versa (Fig.1).The relative importance of lamb carcases of different weight, in relationship to varying concentrate costs shows according to the conditions given in the model that when the price per kg meat is equal regardless of the carcase weight, that a 25 kg carcase is more efficient than producing a 20 kg carcase. On the other hand, if the meat of a 25 kg carcase is only valued at 90% of that of the 20 kg carcase, then the 20 kg carcase is preferable (Fig.2).Using the formula formerly developed for meat production and now expanded for other purposes 64 000 model calculations were made. The change of efficiency through changing of wool price, through increasing the level of fertility, through altering of working time and cost per hour as well as other factors, was illustrated by means of a few examples (Fig.3 and 4).The results of special calculations of efficiency should not be generalised even through they could be of valuable help in breeding, management techniques and making economic decisions in business under given conditions.     

Effect of subsidy regimes on economic values of functional traits in beef cattle breeding

We investigated the impact of five monetary subsidy regimes on economic values of traits in a cow–calf pasture production system with surplus calves fed for slaughter. The following regimes were analysed: (1) maximum prices for slaughter animals actually received in the Czech Republic during 2004, with no subsidies of any kind; (2) prices as in (1), with subsidies awarded per hectare of permanent grassland and per calf born; (3) prices as in (1), with subsidies awarded per hectare of agricultural land, per hectare of pasture and meadow, per beef cow in a forage system and per livestock unit; (4) prices as in (1), with subsidies awarded per hectare of agricultural land; (5) no subsidies, but prices received for slaughter animals that covered production costs and resulted in 1% profitability. The modelled farm showed negative profit under real price conditions with no subsidies (regime 1), which led to an underestimation of economic values for functional traits. The same results were obtained in regimes in which subsidies did not depend on the number of animals (3) or on meat production from the enterprise (4). Economic values of production traits (growth and carcass traits) did not vary among subsidy regimes. To determine optimum economic values for functional traits in beef cattle, we advocate using the method applied in subsidy regime 5, no subsidies but prices for slaughter animals that cover production cost and a small profit.     

Exploring the economic potential of reducing broiler lameness

1. The present study was designed first to explore the potential economic benefits of adopting management practices to reduce lameness in broiler farms, and second to explore farmers’ possible perceptions of this potential in the Swedish context. The likely financial effects were addressed using a normative economic model, whereas a questionnaire-based survey was used to obtain in-depth knowledge about the perceptions of a group of broiler farmers in Sweden.

2. The three alternative practices (out of 6 tested) which realised the greatest improvements in gross margin and net return to management compared to the conventional practice were feeding whole wheat, sequential feeding and meal feeding.

3. The model showed that the negative effect of feeding whole wheat on feed conversion rate was outweighed by the effect of a low feed price and the associated decrease in feed costs. The price of wheat played a major role in the improvement of economic performance, whereas the reduction of lameness itself made a relatively minor contribution.

4. Apparently, the surveyed farmers do not recognise the potential of the positive effects of changing feed or feeding practices on both broiler welfare and farm economics although their implementation can be of great importance in the broiler sector where profit margins are very tight.?     

Early and temporary quantitative food restriction of broiler chickens. 1. Effects on performance characteristics, mortality and meat quality

1. An experiment was conducted with broiler chickens to determine the effects of different early food restrictions, strain (Ross 508 and Hybro G) and sex on performance, mortality carcase composition and meat characteristics. 2. Birds were restricted to 80% or 90% of ad libitum intake for 4 d (80%-4 d-group and 90%-4 d-group, respectively) or 80% for 8 d (80%-8 d-group). All restrictions started on d 4. After the periods of restriction, all birds were fed ad libitum. 3. Only the 90%-4 d-group reached a final body weight not significantly different from, but lower than, the ad libitum group. The other restrictions were too severe to allow a sufficient 'catch-up'. 4. No significant differences in food conversion and total carcase fat content between groups were observed. Abdominal fat showed a tendency to increase due to the restrictions induced. 5. There was a slight trend towards a reduced mortality and of 'sudden death syndrome' but no clear effect of food restriction on number of chickens removed with leg problems. There was no significant decrease in uniformity of the flocks due to restriction. 6. The group 80%-8 d had a significant lower yield percentage. Cut-up parts and meat quality were not changed by restriction. Ross birds had a significantly higher proportion of breast meat than Hybro chickens. Meat of female chickens seemed to be paler than that of males, possibly because of the higher proportion of carcase fat. 7. Food restriction did not always give good results. However, a mild restriction (90% for 4 d) may offer some economic advantages over an ad libitum feeding regimen, mainly by reducing mortality.     

Growth performance and carcase quality in broiler chickens fed on bacterial protein grown on natural gas

1. The effects of increasing concentrations (0, 40, 80 or 120 g/kg) of bacterial protein meal (BPM) and bacterial protein autolysate (BPA) grown on natural gas on growth performance and carcase quality in broiler chickens were examined. 2. Adding BPM to diets reduced feed intake and improved gain: feed from 0 to 21 d and overall to 35 d, but did not significantly affect weight gain compared to the soybean meal based control diet. 3. Increasing concentrations of BPA significantly reduced growth rate, feed intake, gain: feed, carcase weight and dressing percentage, but significantly increased carcase dry matter, fat and energy content. 4. Adding BPM to diets had no effect on viscosity of diets and jejunal digesta, and minor effects on litter quality, whereas BPA increased the viscosity of diets and jejunal digesta, improved litter quality at 21 d, but decreased litter quality at 32 d. 5. To conclude, broiler chickens performed better on a BPM product with intact proteins than on an autolysate with ruptured cell walls and a high content of free amino acids and low molecular-weight peptides.     

Breeding goals for the Kenya Dual Purpose goat. II. Estimation of economic values for production and functional traits

Economic values for production traits (milk yield, MY, kg; 12-month sale weight, LW, kg; consumable meat percentage, CMP) and functional traits (doe live weight, DoWT, kg; number of kids weaned, NKW; kidding frequency, KF; kidding rate, KR, %; doe weaning rate, DoWR, %; doe survival rate, DoSR, %; post-weaning survival rate, PoSR, %; pre-weaning survival rate, PrSR, % and; residual feed intake of yearlings, RFIgamma, kg and does RFId, kg) were estimated for the Kenya Dual Purpose goat (KDPG) for systems under two bases of evaluation. The production systems included smallholder low-potential (SLP), smallholder medium-potential (SMP) and smallholder high-potential (SHP), while the bases of evaluation considered were fixed flock-size and fixed feed resource. Under both bases of evaluation, economic values were highest in SMP apart from the economic values for feed intake-related traits (RFIy and RFId). In SMP, the economic values under fixed flock-size scenario were KSh 71.61 (LW), 20.90 (MY), 45.20 (CMP), 13.68 (NKW), 3.61 (KF), 6.52 (KR), 12.39 (DoWR), 22.96 (DoSR), 22.87 (PoSR), 13.18 (PrSR), -2.76 (RFIy) and -3.00 (RFId). The corresponding economic values under fixed feed resources scenario were KSh 73.28, 29.39, 45.20, 16.91, 4.76, 9.45, 13.84, 25.67, 25.15, 16.19, -2.76 and -3.00. Generally in all production systems, economic values for most traits were higher under fixed feed resource than under fixed flock-size scenario. In all systems, the economic values for most of the traits were sensitive to changes in prices of feed, milk and meat. The positive economic values for most traits under fixed flock-size scenario and fixed feed resource indicates that a unit increase in genetic merit for the traits would have a positive effect on the profitability of the systems.     

Comparison of three different diets for organic broilers: effects on performance and body condition

1. The aim of this study was to assess the feasibility of 100% organic feed for organic broilers by comparing it with 80% organic feed (situation at the time of the experiment; 2004) and 95% organic feed (alternative). 2. Diets were optimised for nutritional value, allowing a maximum 10% increase in feed price when using 100% organic feedstuffs. This could only be achieved at the expense of the methionine content. 3. The birds were reared from 0 to 3 weeks of age in a broiler house in three groups of 500 broilers each on either an 80, a 95 or a 100% organic starter diet. At 3 weeks of age, they were transferred to 15 pens with an outdoor run. Each treatment group of 500 birds was divided into 5 groups of 95 and given an 80, a 95 or a 100% organic finisher diet. 4. Broilers receiving 100% organic feed reached a lower body weight and grew more slowly than those receiving 95% organic feed, mainly because of a lower feed intake. 5. Broilers on 95 or 100% organic feed had a higher incidence of breast blisters than broilers receiving 80% organic feed. 6. The cost price for meat from broilers that received 80% organic feed was euro1.83 per kg live weight. The cost prices for broilers that received 95 and 100% organic feed were euro1.84 (+0.8%) and euro1.93 (+5.4%) per kg live weight, respectively. 7. In conclusion, 95% organic feed led to a better performance than 100% organic feed in this study. Probably, the lower methionine content in the 100% organic feed negatively affected performance. The results for 95% organic feed were similar to 80% organic feed, except for a higher incidence of breast blisters.     

The effect of date fibre supplemented with an exogenous enzyme on the performance and meat quality of broiler chickens

1. Two experiments were conducted to evaluate the use of date fibre as a partial replacement of maize as a source of energy for growing broiler chicken. In experiment 1, date fibre was given alone to determine apparent metabolisable energy (AME) and apparent ileal digestibility of amino acids and crude fibre. 2. Date fibre had lower AME content (8.7 vs 13.6 MJ/kg) and apparent ileal digestibility coefficients for dry matter (0.35 vs 0.83), crude fibre (0.20 vs 0.54) and amino acids. 3. Based on the results of experiment 1, a growth study was conducted to test the effect of exogenous enzymes on the nutritive value of date fibre (experiment 2). 4. Three date fibre contents (5, 10 and 15%) with and without enzyme supplementation were evaluated. Daily feed intake, body weight gain and feed conversion ratio were measured. At the end of experiment 2, 160 birds were randomly selected and slaughtered to evaluate carcase and meat quality traits as well as measuring ileal viscosity. 5. Substitution of maize by 10 and 15% date fibre significantly depressed AME. Enzyme supplementation did not improve crude fibre digestibility. The inclusion of date fibre in the diets except at 5% decreased average daily gains, feed intake and feed conversion ratio. 6. Addition of date fibre caused a significant increase in the weights of total digestive tract, pancreas and caecum. Addition of date fibre or the exogenous enzyme had no significant effect on carcase or meat quality characteristics. 7. Date fibre increased ileal digesta viscosity compared to the control. Addition of the exogenous enzyme decreased the viscosity of the basal diets but had no effect on the date fibre diets.8. This study indicated that date fibre can be included at levels of 5% in broiler diets without affecting performance.     

Nutrient density and slaughter age have differential effects on carcase performance,muscle and meat quality in fast and slow growing broiler genotypes

1. A 2?×?2 factorial design was used to investigate the differences in carcase, muscle and meat characteristics between fast and slow growing genotypes fed on low nutrient (LND) or high nutrient diets (HND) at their respective slaughter ages.

2. The birds were randomly assigned to treatments with 5 replicates of 145 birds for Wens Yellow-Feathered Chicken (WYFC, 5·75 birds/m²) or 115 birds for White Recessive Rock Chicken (WRRC, 7·25 birds/m²), according to the commercial recommendations for the two breeds and were fed on HND or LND. Birds were slaughtered at 63?d and 105?d of age.

3. The results showed WRRC had higher carcase yield and meat yield than that of WYFC, lower fat content, higher moisture content and lower cooking loss. The meat from WRRC was less tender and contained lower levels of polyunsaturated fatty acids (PUFA).

4. Birds fed on HND had higher breast meat yield, myofiber area and protein content in the breast muscle and lower fat content than birds fed on LND. The thigh muscle of birds fed on HND had higher levels of PUFA. Age had a positive effect on carcase parameters, but a negative effect on pH, meat tenderness and cooking loss, and the two genotypes exhibited different responses to the influence of nutrient density and age.

5. Genotype and age had the largest effect on carcase performance and meat quality. LND benefited meat quality and WRRC had larger responses in meat yield and shear force when fed on HND.     

Breeder hen dietary L-carnitine affects progeny carcase traits

(1) Ross 308 broiler breeder hens were given diets containing 0 or 25 mg L-carnitine/kg from 21 weeks of age. (2) Hens were inseminated with semen from Ross broiler breeder males and subsequent growth performance and carcase traits, of progeny obtained from hatches at 30, 35 and 37 weeks of age, were evaluated. (3) Progeny were hatched in a common facility and separated by gender. Experimental treatments employed for the 30-, 35- and 37-week hatches, respectively, were: hen diet and progeny gender (16 replications with two subplots); hen diet, progeny diet (0 and 50 mg L-carnitine/kg of diet) and progeny gender (16 replications with 4 subplots); and hen diet and progeny diet (high and low density; 16 replications with two subplots). (4) Females had lower growth rate and less breast meat, but greater proportions of carcase fat and breast meat than males. Growth performance measurements of progeny were not affected by hen L-carnitine, but hen L-carnitine decreased abdominal fat in progeny. Increasing diet density in the chick diets increased growth and carcase weights. Hen and progeny dietary L-carnitine interacted to increase male mortality. However, dietary hen L-carnitine decreased carcase fat and increased breast meat in progeny fed on high nutrient density diets. (5) In conclusion, L-carnitine in the diet of hens affected carcase traits of their progeny.     

Effects of dietary rosemary, rosemary volatile oil and vitamin E on broiler performance, meat quality and serum SOD activity

1. The current study was conducted to evaluate the effects of dietary supplementation with vitamin E (as alpha-tocopherol acetate), dried rosemary leaves and rosemary volatile oil on the performance, meat quality (measured as sensory variables, pH, colour, malondialdehyde (MDA) level, and bacteria count) and serum superoxide dismutase (SOD) activity in broilers fed on maize-soybean meal based diets. 2. A total of 800 broiler chicks were randomly allocated to 8 dietary treatments, which were set up with 1 control group and 7 experimental groups. The control group (VitE1) was given a basal diet including 50 mg/kg alpha-tocopherol acetate, while the experimental groups were given 5 x 7 g/kg rosemary plant (R1), 8 x 6 g/kg plant (R2), 11 x 5 g/kg plant (R3), 100 mg/kg plant oil (RO1), 150 mg/kg plant oil (RO2), 200 mg/kg plant oil (RO3) or 200 mg/kg alpha-tocopherol acetate (VitE2). 3. Although there were no statistical differences observed for feed consumption, other performance variables including live weight gain, feed efficiency and carcase yield were significantly affected. The addition of rosemary volatile oil had more effect on the performance variables than did the rosemary plant itself. 4. As a measure of meat shelf life, TBA analyses were performed on the meat samples on d 1, 3 and 5 after culling. Meat MDA levels of groups fed diets with rosemary and rosemary volatile oil were significantly lower than that of groups fed diets containing alpha-tocopherol acetate alone. 5. Significant differences were also seen between the control and experimental groups for meat colour and meat pH values as well as for sensory analyses. 6. Microbiological analyses conducted at the end of the experiment showed that E. coli counts were significantly reduced in meat samples from the experimental groups. 7. In conclusion, dietary supplementation with rosemary and its volatile oil improved broiler meat quality. Moreover growth performance was positively affected by the rosemary volatile oil supplementations.     

Genetic evaluation of meat quality traits and their correlation with growth and carcase composition in Japanese quail

1. Estimates of heritability, genetic and phenotypic correlations of performance and meat quality traits were obtained in a population of Japanese quail using restricted maximum likelihood (REML) procedures.

2. The heritability estimates for body weight (BW) traits ranged from 0·15 at hatch to 0·42 at six weeks. For carcase composition traits, heritability estimates ranged from 0·12 for carcase yield to 0·26 for abdominal fat yield and for meat quality traits they ranged from 0·18 for drip loss to 0·54 for yellowness of the meat.

3. Negative genetic correlations were found between BW and carcase traits with ultimate pH and drip loss ranging from ?0·01 (BW at hatch) to ?0·40 (skin yield). Redness and yellowness showed negative genetic correlations with BW and carcase traits, whereas the genetic correlations with lightness were positive (from 0·04 to 0·43).

4. Shear force and cooking loss showed positive genetic correlations with carcase, breast, abdominal and skin yield.

5. In conclusion, meat quality traits have the potential to be improved through genetic selection but selection for higher BW and carcase composition may reduce the meat quality of Japanese quail through reducing redness, ultimate pH and intramuscular fat and increasing lightness, shear force and cooking loss of the meat.     

The use of dried bakery products in a free-choice feeding method for small-scale broiler production

Waste material from bakeries is an unconventional energy feed source which is available in sufficient quantities for use in small-scale broiler production in South Africa. Small-scale broiler producers do not have access to the computer programs required to balance home-mixed rations. This investigation confirms that the use of dried bakery products (DBP) in a 2-stage, free-choice method can be used to compensate for this lack. A total of 570 day-old male broiler chickens was assigned to 3 feeding treatments: the control group was fed a 2-stage feeding programme using standard commercial starter and grower rations. The 2nd group received a commercial starter ration up to Day 7 and was thereafter given a choice of a commercial starter ration with normal salt content (0.35%) and DBP. The 3rd group was fed a commercial starter ration up to Day 7, then offered a choice of commercial starter ration with a lower salt content (0.1%) and DBP. The low salt alternative was used to test whether the higher salt percentage in DBP influenced the choice of feed by the birds. It was found that the control group consumed significantly more feed (P < 0.05) and was significantly heavier (P < 0.05) than the experimental groups. However, there was no significant difference between the 2 experimental groups, which indicated that salt content did not play a role in the choice of ration. Feed consumption by both experimental groups was about one-third less than the control group, but the profit margin, as calculated using gross margin analysis, was approximately 15 % higher. It was therefore concluded that dried bakery products can be profitably incorporated as an energy feed source, using the free-choice feeding method, in small-scale broiler enterprises.     

Influence of dietary energy on bird performance,carcase parts yields and nutrient composition of breast meat of heterozygous naked neck broilers reared at natural optimum and summer temperatures

1. Heterozygous naked neck birds were raised under natural spring (average 21.2°C) and summer temperatures (average 27.1°C) to investigate the influence of dietary energy on broiler performance, carcase yield and nutrient composition of breast meat. 2. Birds were fed on a low energy diet of 12.12 MJ ME/kg, a medium energy diet of 12.96 MJ ME/kg and a high energy diet of 13.79 MJ ME/kg with 2 protein concentrations per energy treatment, 230 and 200 g/kg, from 0 to 3 and 3 to 7 weeks of age, respectively. 3. Summer rearing resulted in a decrease in body weight, body weight gain, carcase weight and carcase part yields of birds. 4. Increasing dietary energy from 12.12 to 13.79 MJ ME/kg increased body weight at 3 and 7 weeks, body weight gains from 0 to 3 and 3 to 7 weeks, carcase weights and relative abdominal fat weights of birds in a linear manner. There was no effect of dietary energy on the nutrient composition of breast meat. 5. It was concluded that there was no differences in dietary energy requirements of heterozygous naked neck birds when grown under natural optimum (21.2°C) and summer temperatures (27.1°C).     

Effect of dietary lysine to crude protein ratio on performance of male Ross 308 broiler chickens

Two experiments were conducted to determine the effect of dietary lysine to crude protein ratio on performance of male Ross 308 broiler chickens. In each experiment the diets were isocaloric and isonitrogenous but with different lysine to crude protein ratios. A complete randomized design was used in both experiments, the starter (1–21 days) and grower (22–42 days) experiments. The three starter diets, based on lysine to crude protein ratios, were L₀ (0.055), L₁ (0.066) and L₂ (0.077), while grower diets were L₃(0.047), L₄(0.061) and L₅(0.074). A quadratic type equation was used to determine ratios for optimum growth rate, feed conversion ratio, breast meat yield and breast meat nitrogen content. Dietary lysine to crude protein ratios of 0.066 and 0.077 supported optimum growth rate and feed conversion ratio, respectively, during the starter period. Dietary lysine to crude protein ratios of 0.073, 0.073, 0.069 and 0.079 supported optimum growth rate, feed conversion and breast meat yield and nitrogen content during the grower phase. Dietary lysine to crude protein ratio had no effect on diet intake and digestibility. The results indicate that at each phase a single dietary lysine to crude protein optimized both growth rate and feed conversion ratio. However, the ratio for optimum breast meat yield was lower than that for optimum growth rate and feed conversion ratio. These findings have implications on ration formulation for broiler chickens.     

The nutrition of poultry as a factor affecting litter quality and foot pad dermatitis – an updated review

Foot pad dermatitis (FPD), a condition of inflammation and necrotic lesions on the plantar surface of the footpads, is commonly observed in fast‐growing broiler chickens and turkeys. FPD negatively affects the welfare of birds, performance indices and the economic profit of poultry meat production. Nutrition is an important factor affecting water intake, excreta moisture and litter quality and, in this way, the occurrence and intensity of FPD in birds. This article reviews and discusses the recent results published in the literature on the effects of nutritional factors on litter quality and FPD severity in broiler chickens and turkeys. Literature data on the efficacy of nutritional methods on the litter quality and FPD occurrence are not consistent. However, the results of several experiments indicate that the optimal level of crude protein, biotin and electrolytes (Na, K) in the diet, as well as feed additives such as feed enzymes hydrolysating non‐starch polysaccharides and organic sources of microelements (zinc), may reduce the litter moisture as well as FPD incidence and severity in broiler chickens and turkey.     

Impact of feeding 2-hydroxy-4-(methylthio)butanoic acid and DL-methionine supplemented maize-soybean-rapeseed meal diets on growth performance and carcase quality of broilers

1. This experiment was conducted to compare the effectiveness of DL-2-hydroxy-4-(methylthio)butanoic acid (HMTBA) and DL-methionine (DLM) on growth performance and carcase quality of broilers in a 2 x 3 x 2 factorial experimental design including two methionine (Met) sources, three equimolar levels of Met supplementation and two sexes. 2. No difference was observed between the two Met sources in growth performance and muscle deposition from 10 to 49 d. With increasing Met levels, average daily gain was increased in the starter, grower and overall phases, average daily feed intake was increased in the starter phase, and feed:gain ratio was decreased in the grower and overall phases. Met supplementation increased breast muscle content and decreased abdominal fat content. Broilers given HMTBA had breast and thigh muscle coloration that was characterised as superior to those fed DLM. 3. These results indicated that Met supplementation improved growth performance and carcase quality irrespective of the Met sources. Compared to DLM, HMTBA has the same molar bioefficacy for improving the growth performance and carcase quality; however, HMTBA-fed birds had superior meat colour to DLM-fed birds.     

Beta-agonists as repartitioning agents: a review

Several beta-adrenergic agonist compounds are undergoing commercial development as carcase repartitioning agents. Significant increases in feed conversion efficiency, carcase lean content and decreases in carcase fatness have been reported consistently in all the major meat animal species. The use of these compounds is consistent with consumer demand for leaner meat but could prove controversial in the current political climate in the EC.