Range Production Systems Research Articles

Growth performance of different strains of indigenous Tswana chickens under intensive management system

Indigenous Tswana chickens are traditionally kept under free range production system and their growth performance under an intensive management system have not been evaluated. The purpose of this study was therefore to evaluate the growth performance of the naked neck, dwarf and normal-feathered strains of indigenous Tswana chickens under an intensive management system. A total of 74, 43 and 44 Tswana chickens of the normal, dwarf and naked neck strains, respectively, were wing-tagged and evaluated for growth performance (body weight, body length and shank length) from 4 to 20 weeks of age. The chickens were raised under deep litter management system and were fed commercial broiler feeds ad libitum. Sex had a significant (P < 0.05) influence on body weights, shank length and body length of only the normal and naked neck strains. Males of all the strains were generally heavier and had longer bodies and shanks than their age-matched female counterparts. Generally, naked neck males and females were the heaviest and had the longest bodies and shanks, while dwarf males and females were the lightest and had the shortest bodies and shanks. The naked strain had superior growth performance compared to the normal-feathered and dwarf strains. Key words: Growth, Tswana chickens, intensive management.

ATP-driven Reduction by Dark-operative Protochlorophyllide Oxidoreductase from Chlorobium tepidum Mechanistically Resembles Nitrogenase Catalysis

During chlorophyll and bacteriochlorophyll biosynthesis in gymnosperms, algae, and photosynthetic bacteria, dark-operative protochlorophyllide oxidoreductase (DPOR) reduces ring D of aromatic protochlorophyllide stereospecifically to produce chlorophyllide. We describe the heterologous overproduction of DPOR subunits BchN, BchB, and BchL from Chlorobium tepidum in Escherichia coli allowing their purification to apparent homogeneity. The catalytic activity was found to be 3.15 nmol min(-1) mg(-1) with K(m) values of 6.1 microm for protochlorophyllide, 13.5 microm for ATP, and 52.7 microm for the reductant dithionite. To identify residues important in DPOR function, 21 enzyme variants were generated by site-directed mutagenesis and investigated for their metal content, spectroscopic features, and catalytic activity. Two cysteine residues (Cys(97) and Cys(131)) of homodimeric BchL(2) are found to coordinate an intersubunit [4Fe-4S] cluster, essential for low potential electron transfer to (BchNB)(2) as part of the reduction of the protochlorophyllide substrate. Similarly, Lys(10) and Leu(126) are crucial to ATP-driven electron transfer from BchL(2). The activation energy of DPOR electron transfer is 22.2 kJ mol(-1) indicating a requirement for 4 ATP per catalytic cycle. At the amino acid level, BchL is 33% identical to the nitrogenase subunit NifH allowing a first tentative structural model to be proposed. In (BchNB)(2), we find that four cysteine residues, three from BchN (Cys(21), Cys(46), and Cys(103)) and one from BchB (Cys(94)), coordinate a second inter-subunit [4Fe-4S] cluster required for catalysis. No evidence for any type of molybdenum-containing cofactor was found, indicating that the DPOR subunit BchN clearly differs from the homologous nitrogenase subunit NifD. Based on the available data we propose an enzymatic mechanism of DPOR.

Análise da evolução da resposta à selecção numa população da raça bovina mertolenga

The is a Portuguese native beef breed witch inhabits in the Alentejo country (south of Portugal). It is very well adapted to perform in range production systems. A herd of Mertolengo breed were utilized for the evaluation of response to selection, over forteen years. Field data were recorded and the weights were adjusted for 3 and 6 months of age. For those traits, realized heritabilities were estimated, combining the two sexes and utilizing the total response to selection and the weighted cumulative selection differentials. The values reached were, respectively, 0,28 and 0,29 for 3 months and 6 months age weight. The evaluation of selection response, on the female side, fallowed the gene flow method referred by Elsen & Mocquot (1974), taking in account the age structure of the female population. Through this method it was possible to evaluate the changes year by year. The female contribution to the genetic progress was very low, and frequently negative, when compared with bulls. The amount of response achieved was entirely due to the bulls.

Method for checking label accuracy in barn and free range eggs

AbstractThe aim was to develop a method for testing whether eggs sold as either ‘barn’ or free range' were laid under cage conditions. The surface patterns on 11 520 eggs from cage, barn and free range production systems were examined under ultraviolet light for distinctive fluorescent marks associated with each production system. In addition, the effects of egg washing, egg size, condensation and cage dusting on the prevalence of the fluorescent patterns associated with the cage production system were examined. The prevalence of fluorescent white double parallel lines with 2.2–2.5 cm spacing was a distinguishing feature for eggs laid on wire floors in cages. If five or more eggs in a sample of 90 eggs have double fluorescent lines it can be concluded with greater than 999 in 1000 probability that the batch contains some cage‐laid eggs. Dust from the egg collection area below the feed trough was the main source of the fluorescent material. Washing the eggs removed or obscured the double lines. Egg size and condensation had limited effects on the prevalence of double lines. Infrequent dusting of the wire floor did not reduce the value of the test. Copyright © 2005 Society of Chemical Industry

Feed and strain effects on the use of outdoor areas by broilers

1. The use of outdoor areas by two broiler strains, known to have different growth rates and with access to either moderate (M) or low (L) energy feeds, was examined to assess the consequences for production, meat quality, health and welfare. 2. Sixteen groups of either Ross 208 (ROSS) or a Labresse cross (LAB) were fed either feed M or L. They were raised indoors until 42 d of age when groups of 102 birds were moved to outdoor houses with free access to an outdoor area. 3. The number of chickens standing and lying, respectively, in each of 5 zones in the outdoor area were recorded at intervals throughout the outdoor growth period until slaughter at 84 d of age. Production variables were measured, and gait, feather condition, litter quality, and dermal lesions on foot-pads and hocks were scored together with objective meat quality measures. 4. Both strains showed a diurnal rhythm with most birds observed outside around sunrise and before sunset. Feed and strain both affected the distribution of the birds on the outdoor area, with more birds on feed M than L observed outside, and with more LAB birds outside and using more of the outdoor area than ROSS. This was reflected in some of the carcase and meat quality measures. Feather pecking and cannibalism only occurred in LAB. 5. ROSS was found to have a faster growth rate, poorer litter quality, more dermal lesions and impaired mobility, reflected in low usage of outdoor area and poor gait score compared with LAB. 6. This together with the presence of pectoral myopathies make ROSS unsuitable for 12 week growth in free range production systems. The occurrence of feather pecking and cannibalism in LAB make this particular Labresse cross questionable for meat-type poultry production.

Feed and strain effects on the use of outdoor areas by broilers

1. The use of outdoor areas by two broiler strains, known to have different growth rates and with access to either moderate (M) or low (L) energy feeds, was examined to assess the consequences for production, meat quality, health and welfare. 2. Sixteen groups of either Ross 208 (ROSS) or a Labresse cross (LAB) were fed either feed M or L. They were raised indoors until 42 d of age when groups of 102 birds were moved to outdoor houses with free access to an outdoor area. 3. The number of chickens standing and lying, respectively, in each of 5 zones in the outdoor area were recorded at intervals throughout the outdoor growth period until slaughter at 84 d of age. Production variables were measured, and gait, feather condition, litter quality, and dermal lesions on foot-pads and hocks were scored together with objective meat quality measures. 4. Both strains showed a diurnal rhythm with most birds observed outside around sunrise and before sunset. Feed and strain both affected the distribution of the birds on the outdoor area, with more birds on feed M than L observed outside, and with more LAB birds outside and using more of the outdoor area than ROSS. This was reflected in some of the carcase and meat quality measures. Feather pecking and cannibalism only occurred in LAB. 5. ROSS was found to have a faster growth rate, poorer litter quality, more dermal lesions and impaired mobility, reflected in low usage of outdoor area and poor gait score compared with LAB. 6. This together with the presence of pectoral myopathies make ROSS unsuitable for 12 week growth in free range production systems. The occurrence of feather pecking and cannibalism in LAB make this particular Labresse cross questionable for meat-type poultry production.

Usefulness of subjective ovine milk scores: II. Genetic parameter estimates.

Genetic parameters for a subjective milk score given to ewes within 24 h of parturition were estimated to determine the usefulness of milk score as a selection trait to improve milk production, which influences total litter weight weaned. Heritability of milk score and the genetic correlation of milk score with litter weight weaned were estimated by REML separately for four sheep breeds, Rambouillet (n = 1,731), Targhee (n = 1,638), Columbia (n = 1,731), and Polypay (n = 1,129). Litter weight weaned was the total weight of lambs weaned at approximately 120 d of age under a western range production system. Observed heritability estimates for milk score at first parity were moderate and similar among breeds, ranging from 0.18 to 0.32. Heritability estimates adjusted for a binomial distribution of milk scores at first parity were high (Columbia, 0.43; Polypay, 0.35; Rambouillet, 0.50; Targhee, 0.84). Estimates of observed heritability for second-parity milk score were moderate to high, ranging from 0.23 to 0.46. Milk score at first or second parity was genetically correlated with milk score records at maturity (third parity and greater), with estimates ranging from 0.69 to 1.00. Milk score and litter weight weaned were genetically correlated at first or second parity in Rambouillet (r(g) = 1.00) and Targhee breeds (r(g) = 1.00 and 0.61, respectively), but not in the Columbia and Polypay breeds. Estimates of heritability for lifetime records for milk score ranged from 0.16 to 0.26 across breeds. Estimates of genetic correlations of annual lifetime milk score records with litter weight weaned were high (Columbia, 1.00; Polypay, 0.81; Rambouillet, 1.00; and Targhee, 0.77). Repeatability estimates for milk score were similar across breeds, 0.23 for Columbia, Rambouillet, and Targhee ewes and 0.28 for Polypay ewes. Milk score measured at first or second parity may be a good predictor of future potential milking ability. Further, milk score can be used as a selection trait to improve maternal ability for increasing litter weight weaned. The need for increasing ewe milking performance and lamb growth rate at first parity in commercial range sheep production systems may be addressed by selection for milk score at first parity.

Life cycle evaluation of five biological types of beef cattle in a cow-calf range production system: II. Biological and economic performance.

Results from a 10-yr study of five dam breed groups in a range beef production system were used as inputs to a simulation model to evaluate life cycle biological and economic performance. Dam breed groups were straightbred Herefords (HH), Angus-Hereford and Simmental-Hereford F1 crosses (AH and 1S1H), 75% Hereford-25% Simmental (1S3H), and 25% Hereford-75%. Simmental (3S1H). Biological measures were number of lifetime matings, calves weaned and kilograms of calf weight sold per cow exposed, and metabolizable energy (ME) consumed per kilogram of calf weight sold and per kilogram of total weight sold. Simulated economic measures were break-even steer prices, total production costs, net profit per cow exposed, and net profit for a ranch of fixed size. The HH and 3S1H dams consumed the least ME per kilogram of total weight sold yet had the highest steer break-even prices and lowest profits. The F1 dams yielded consistently higher profits than other dam breed groups. Breed group rankings were not sensitive to prices paid for hay or calf prices relative to cow prices. Regression techniques were used to estimate maternal heterosis and maternal breed substitution effects from the simulated data. Maternal heterosis effects were large and highly significant for all measures of system performance and were desirable for all traits except ME/kilogram of total weight sold. Maternal heterosis for net profit was nearly $70.cow-1.yr-1 and $20,400/yr for a ranch of fixed size (2,700 AUM range forage). Maternal breed substitution effects were generally much smaller than heterosis effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Life cycle evaluation of five biological types of beef cattle in a cow-calf range production system: I. Model development.

Data collected during a 10-yr study at the Northern Agricultural Research Center (NARC), Havre, MT were used in construction of a simulation model to evaluate production systems using different breed groups. Five dam breed groups, straightbred Hereford (HH), 50% Angus-50% Hereford (AH), 25% Simmental-75% Hereford (1S3H), 50% Simmental-50% Hereford (1S1H), and 75% Simmental-25% Hereford (3S1H), were studied. The simulated system was a northern range cow-calf production system with spring calving and fall weaning. Replacement heifers were purchased and all calves were marketed at weaning. All nonpregnant females were sold in the fall. Statistical analyses of the data yielded input values (least squares means for breed group x age x sex subclasses) for cow and calf weights, pregnancy rate, dystocia, and calf survival. Pregnancy, dystocia, calf survival, calf weights, and cow weights were simulated stochastically. Energy requirements for maintenance, growth, gestation, and lactation were predicted from equations adapted from the literature based on body weight, frame size, sex, and breed group. Economic inputs and outputs were computed by accounting for variable input expenses and output revenues associated with animal performance and fixed costs associated with range management. Simulated measures of system performance included measures of energy conversion, break-even prices, and profit.