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PubMed1991

Genetic parameters of growth, feed intake, feed conversion and carcass composition of dual-purpose bulls in performance testing.

Genetic parameters for growth, total energy intake, feed conversion ratio, average daily energy intake and carcass composition were estimated in an experiment with 650 bull calves from 31 half-sib groups of Holstein Friesian or Brown Swiss sires. All traits analyzed had an amount of additive genetic variance that allows for considerable response to selection. No interaction between genotype (sire group) and proportion of roughage in the diet was found. Daily gain was strongly correlated negatively with feed conversion ratio but positively correlated with daily energy intake. Results indicate that genetic selection for either daily gain or average daily energy intake would decrease carcass fatness at a constant slaughter weight. However, the environmental correlation between daily energy intake and carcass fatness was positive.

Animals↗
PubMed1995

Response of rainbow trout (Oncorhynchus mykiss) growing from 50 to 170 g to supplements of either L-arginine or L-threonine in a semipurified diet.

We studied the effects of increasing dietary concentrations of either L-arginine or L-threonine on growth, feed intake, feed conversion ratio and composition of gain in rainbow trout. Semipurified diets containing 20.1 MJ digestible energy/kg dry matter, with wheat gluten and crystalline amino acids as sole sources of amino acids, were fed to rainbow trout (initial mean body weight 47 +/- 0.7 g). In one series of 12 diets, arginine concentration ranged from 5.0 to 23.8 g/kg dry matter; in a second series of 12 diets, threonine concentration ranged from 3.7 to 21.0 g/kg dry matter. Each diet was fed to a group of 20 fish. During the experiment of 51 feeding days, dry matter intake, weight gain, feed conversion ratio, protein concentration of gain and total protein deposition followed exponential functions. For achieving 95% of the potential maximum protein deposition, dietary concentrations of 11.6 g arginine and 10.4 g threonine/kg dry matter were required. Arginine and threonine were both utilized most efficiently at dietary concentrations of approximately 6 g/kg dry matter. At low dietary concentrations of arginine, deposition of this amino acid exceeded the quantity fed. Recommended dietary concentrations of arginine and threonine will depend on the trait desired in the trout.

Animal Feed↗
PubMed1997

Response of rainbow trout (Oncorhynchus mykiss) to supplements of individual essential amino acids in a semipurified diet, including an estimate of the maintenance requirement for essential amino acids.

We studied the effects of increasing dietary concentrations of each of the following amino acids on growth, feed intake, feed conversion ratio and composition of gain in rainbow trout in six dose-response experiments: L-lysine, L-tryptophan, L-histidine, L-valine, L-leucine and L-isoleucine. Semipurified diets containing 20.1 MJ digestible energy/kg dry matter, with wheat gluten and crystalline amino acids as sole sources of amino acids, were fed to rainbow trout [initial mean body weight (BW) 40-51 g, depending on the amino acid studied]. In one series of 24 diets, lysine concentration ranged from 4.5 to 58.0 g/kg dry matter; in five further series of 12 diets each, concentrations ranged from (in g/kg dry matter): tryptophan, 1.3 to 5.6; histidine, 2.6 to 13.5; valine, 6.2 to 34.2; leucine, 10.0 to 42.0 and isoleucine, 5.0 to 15.3. Each diet was fed to a group of 20 fish for 53-64 d, depending on the amino acid studied. Dry matter intake, weight gain, feed conversion ratio, protein concentration of gain and total protein deposition followed exponential response functions. To achieve 95% of the maximum protein deposition, dietary concentrations of 27.7 g lysine, 2.0 g tryptophan, 5.8 g histidine, 15.7 g valine, 13.6 g leucine and 13.7 g isoleucine/kg dry matter were required. Maintenance requirements, estimated from exponential functions for protein deposition, were [in mg/(100 g BW.d)]: lysine, 1.93; tryptophan, 1.05; histidine, 1.07; valine, 2.92; leucine, 8.26 and isoleucine, 0.91. This corresponds to 4% of the requirement for protein deposition for lysine and isoleucine but 32% for leucine, with the other amino acids being intermediate. Therefore, different dietary amino acid requirement patterns were derived from protein deposition data depending on the chosen level of performance.

Amino Acids, Essential↗
PubMed1999

A compartmentalised model for the estimation of the cost of coccidiosis to the world's chicken production industry.

A compartmentalised model is presented for the estimation of the monetary losses suffered by the world's poultry industry resulting from coccidiosis of chickens and costs of its control. The model is designed so that the major elements of loss may be separately quantified for any chicken-producing entity, e.g., a farm, a poultry company, a country, etc. Examples are presented and the sources, reliability and geographical relevance of the data used for each parameter are provided. Loss elements for specific geographical areas should be recalculated at appropriate intervals to take into account local and international fluctuations in costs of chicks feed, labour, financial inflation and world currency exchange rates. Equations are given for relationships among numbers of chickens, liveweights, weights of carcasses, feed consumptions, feed conversion ratio (FCR), prices of feeds, prices of anticoccidial therapeutic and prophylactic drugs, values of chickens, chicken rearing costs; and effects of coccidiosis on mortality, weight gain and FCR. Using these equations, it is theoretically possible for an international team of representatives, each using reliable local data, to calculate simultaneously each relevant loss element for their respective countries. Addition of these elements could give, for the first time, an accurate global estimate of the losses due to chicken coccidiosis. The total cost of coccidiosis in chickens in the United Kingdom in 1995 is estimated to have been at least GB pound silver 38 588 795, of which 98.1% involved broilers (80.6% due to effects on mortality, weight gain and feed conversion, and 17.5% due to the cost of chemoprophylaxis and therapy). The costs of poor performance due to coccidiosis and its chemical control totalled 4.54% of the gross revenue from UK sales of live broilers. This model includes a new method for comparing the profitabilities of different treatments in commercial trials. providing actual costs rather than the arbitrary numerical scores of other methods. Although originally designed for the study of coccidiosis, the model is equally applicable to any disease. It should be of value to agricultural economists, the animal feed and poultry industries, animal health companies, and to research scientists (particularly for preparing grant applications).

Animal Husbandry↗
PubMed2026

Genome-wide association studies for feed efficiency, production and feeding behavior traits in Canadian purebred Duroc pigs.

This study aimed to identify potential genetic variants and candidate genes associated with feed efficiency (FE), production, and feeding behavior traits in Canadian purebred Duroc pigs. Genome-wide association studies (GWAS) were conducted using 8,861 individuals and an imputed Affymetrix PigGen Canada 50K panel v2.0 using a linear mixed model (LMM) and a Bayesian B model. This analysis used an adjusted P-value threshold (ranging from 6.6 × 10-5 to 1.3 × 10-4) using a false-discovery rate to determine significance. The number of significant SNPs identified for each trait was as follows: average daily gain (ADG, 48), daily feed intake (DFI, 85), feed conversion ratio (FCR, 101), residual feed intake (RFI, 37), residual gain (RG, 64), residual intake and gain (RIG, 55), backfat thickness (BF, 100), loin depth (LD, 6), Kleiber's ratio (KR, 0), total time spent eating per day (TPD, 7), and number of visits to the feeder per day (NVD, 6). Several traits (BF, DFI, FCR, RFI, RG, and RIG) showed strong overlapping signals on chromosomes 7 and 10 with 24 shared significant SNPs, indicating potential shared genetic mechanisms. These traits also had 71 overlapping candidate genes, such as PACSIN1, PTCH1, ADIPOR1, and ITPR3, associated with glucose, lipid, and cholesterol metabolism. Well-known candidate genes in literature associated with growth and fatness such as MC4R and CDH20 were also identified to be associated with ADG, BF, FCR, and DFI in this study. Gene ontology enrichment analysis revealed that a set of the candidate genes were involved in the gonadotropin-releasing hormone (GnRH) and the platelet-derived growth factor (PDGF) signaling pathways. Overall, this study contributed to understanding the genetic architecture and provided a biological foundation for improving FE, production, and feeding behavior traits in Canadian Duroc pigs, facilitating the selection of more efficient pigs.

Sus scrofa↗
PubMed2004

Heritability of digestibilities and divergent selection for digestion ability in growing chicks fed a wheat diet.

The genetic parameters of digestibilities for a wheat-based diet were estimated on 864 broilers. Two divergent lines (D+ and D-) were developed based on AMEn. The Rialto wheat variety was used as it is known to result in low digestibility values. Digestibility of lipids (DL), starch (DS), and proteins (DP) were measured individually using Near Infrared (NIR) analysis of freeze-dried excreta. Body weight, feed consumption (FC), feed conversion ratio (FCR) and residual feed consumption (RES) were recorded to evaluate their correlation with AMEn. The mean AMEn value was 3,093 kcal/kg DM (CV = 9.0%), with a range of 1,001 to 4,022 kcal/kg DM, and was highly heritable (0.36 to 0.38) based on the Restricted Maximum Likelihood method. Genetic correlations with BW were low (-0.10 to -0.15). Selection for AMEn can thus be performed without modifying BW. In contrast, the estimated genetic correlations between AMEn and the other traits were highly negative (-0.53 to -0.60 for FC, -0.77 to -0.80 for RES, and -0.77 to -0.84 for FCR). Finally, digestibilities of feed components were moderately to highly heritable (0.33 to 0.47) and highly correlated with AMEn (0.91 for DL, 0.83 for DS, and 0.86 for DP). Selecting for improved AMEn should thus improve digestibility of proteins, starch, and lipids. The first generation of divergent selection on AMEn confirmed these results, D+ and D- lines showing a 13% difference in AMEn (P < 0.0001) and similar BW.

Animals↗
PubMed2005

Nitrogen and phosphorus budget in coastal and marine cage aquaculture and impacts of effluent loading on ecosystem: review and analysis towards model development.

Being an essentially open system, cages are usually characterized by a high degree of interaction with environment and cage systems are highly likely to produce large bulk of wastes that are released directly into the environment. Therefore, large-scale cage aquaculture development has been put into question and concerns have been raised that cage aquaculture produces large bulk of wastes that are rich in organic matter and nutrients and are released into coastal and nearshore environment. Recent information on cage aquaculture nutrient budget is scarce and most published reports are dated. This paper reviews cage aquaculture nutrient budget and nutrient loadings and propose a model for nutrient (nitrogen, N and phosphorus, P) budget in a hypothetical cage aquaculture farm with values of feed loss, FCR (feed conversion ratio) and nutrient contents in feed and fish taken from published literature in order to calculate the amount (kg) of N and P produced and released to the environment for each ton of fish produced. The paper proposes, in addition, a critically analyzed nutrient budget based on the dry matter conversion rate instead of the usual feed conversion rate. The conceptual model shows that 132.5 kg N and 25.0 kg P are released to the environment for each ton of fish produced; these values are as high as 462.5 kg N and 80.0 kg P when calculated on the basis of dry matter conversion rate instead of usual feed conversion rate. Thus, the annual global N and P loadings from cage aquaculture (10,000 tons fish and 3000 tons dry matter) are 1325 tons N and 250 tons P and 1387.5 tons N and 240.0 tons P based on usual feed conversion rate and dry matter conversion rate respectively. The paper also proposes, by analyzing the existing data, an FCR-based regression model for predicting nutrient loadings for a given diet. Finally, attempt was made to calculate the annual global loading and release of N and P from cage aquaculture to the coastal and marine environment, the potential impacts of nutrient loading on the ecosystem were discussed and critical points to be considered for minimizing nutrient output in cage aquaculture were suggested.

Animal Feed↗
PubMed2005

Effect of scavenging and supplementation of lysine and methionine on the feed intake, performance and carcase quality of improved dual-purpose growing chickens.

An experiment was conducted with 192 improved dual-purpose chickens from 4 to 12 weeks of age to evaluate the effects of management system (confinement and scavenging) and amino acid supplementation (with and without lysine and methionine) of a low-protein diet on the feed and nutrient intake, performance and carcase quality of improved chickens. Mean daily dry matter (DM), crude protein and metabolizable energy intakes were higher for the confined birds (65 g, 13.3 g and 966 kJ, respectively) than for the scavenging birds (58 g, 12.0 g and 868 kJ, respectively) (p < 0.001) and higher for the unsupplemented (63.3 g, 13.0 g and 945 kJ, respectively) than for the supplemented birds (59.5 g, 12.2 g and 889 kJ, respectively) (p < 0.001). Mean DM intake was 68.0 and 54.9 g/day for the males and females (p < 0.001), respectively. Average daily weight gains (ADG) were higher for scavenging (26.9g) than for confined birds (23.9g) (p < 0.001), higher for supplemented (27.6 g) than for unsupplemented birds (23.2 g) (p < 0.001) and higher for males (27.5 g) than for females (23.3 g) (p < 0.001). Carcase, breast and thigh percentages were higher for supplemented than for unsupplemented birds (p < 0.001) and higher for scavenging than for confined birds (p < 0.001). Abdominal fat percentage was significantly lower for the scavenging treatments compared to the corresponding confined treatments (p < 0.001). Feed conversion ratios (kg feed/kg gain) and feed costs/kg gain were lower for the scavenging than for the confinement treatments, and lower for the supplemented than for the unsupplemented birds (p < 0.001). Supplementation of lysine and methionine in diets that were suboptimal in terms of protein and essential amino acids improved performance and carcase quality and reduced feed costs, in particular of the confined growers.

Animal Feed↗
PubMed1993

Phosphorus studies in pigs. 1. Available phosphorus requirements of grower/finisher pigs.

Two experiments were conducted to determine the available P requirements of grower and grower/finisher pigs and to define the conditions for conducting a growth assay for P availability. In the first experiment, diets with four levels of calculated available P (1-4 g/kg) and four Ca:available P ratios (1.7-2.9) were used to determine the available P requirements of grower pigs. The diets were formulated by substituting the required amounts of limestone and sodium tripolyphosphate for sugar in a soya-bean meal and sugar-based diet. In addition to measuring growth responses, a range of bones were examined to determine the most suitable criteria for assessing the response to available P. There was a small quadratic response of feed intake and growth rate of the pigs to level of available P, with maximum responses occurring to approximately 3 g available P/kg (P < 0.05). There were linear depressing effects of increasing Ca:available P ratios on carcass gain and feed conversion ratio (P < 0.01) but most of these effects occurred when the ratio exceeded 2.5:1. All bone variables examined increased linearly (P < 0.05) or curvilinearly (P < 0.01) with increasing available P concentration. In general, these variables were not affected by the Ca:available P ratio. The results of the growth responses and bone development indicate that the grower pig requires approximately 3 g available P/kg. However, for availability assays, where linearity of response is needed, the dietary concentration of available P should be a maximum of approximately 2 g/kg. In the second experiment four levels of calculated available P (1-4 g/kg) with a Ca:available P ratio of 2.5:1 were used to determine the available P requirements of grower/finisher pigs from 20 to 90 kg live weight. At 50 kg live weight the dietary available P concentration for half the pigs fed at 2, 3 and 4 g available P/kg was reduced to 1, 2 and 3 g/kg respectively. The pigs were fed ad lib, and growth performance, bone characteristics, P retention and ash concentration in the empty body were taken as response criteria to assess P adequacy. Among the variables tested, the ash concentration in the radius/ulna bone and P and ash concentrations in the empty body appeared to be more responsive than other variables to the changes in dietary P levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Animal Nutritional Physiological Phenomena↗
PubMed2004

Physiological responses of broiler chickens to heat stress and dietary electrolyte balance (sodium plus potassium minus chloride, milliequivalents per kilogram).

Individually caged male Cobb broilers (24), 44 d of age, were used to evaluate effects of heat stress (1 d of data collection) and dietary electrolyte balance (DEB; Na + K - Cl, mEq/kg from 1 d of age). During summer rearing, mortality was variable, but DEB 240 improved growth, feed conversion ratio, water intake, and water:feed ratio vs. DEB 0. The temperature sequence for heat stress was 24 to 32 degrees C in 30 min, 32 to 36 degrees C in 30 min, 36 to 37 degrees C in 15 min, and 37 to 41 degrees C in 45 min. Maximum temperature was held for 15, 60, 90, or 360 min for data collection (relative humidity averaged 42 +/- 7%). Results from the same room before and after heat stress were analyzed by DEB (1-factor ANOVA) and before vs. after heat stress compared across DEB (2-sample t-test). Heat stress decreased blood Na, K, and pCO2, and lymphocytes but increased heterophils. Blood HCO3 rose, Cl declined, and hematocrit gave a concave pattern (lowest at DEB 120) as DEB increased. After heat stress, DEB 0 decreased blood Na and K, and DEB 0 and 120 levels decreased blood HCO3. After heat stress blood pCO2 and hemoglobin decreased with DEB 240, but it had highest pCO2, a key factor. The DEB 120 gave longest times to panting and prostration with DEB 0 and 240 results lower but similar statistically. In heat stress, DEB 360 was excessive, DEB 120 and 240 were favorable, and DEB 0 was intermediate based on hematology, panting, and prostration responses.

Acid-Base Equilibrium↗
PubMed2001

Efficiency of different xylanase preparations in diets for pekin ducks.

Four experiments were conducted with a total of 2288 pekin ducks. Day-old ducklings were group-penned on straw bedding and were fed complete, pelleted diets ad libitum for up to 49 days depending on experiment. In each experiment, starter diets (until day 21) and grower diets (from day 22) were used adequate in ME content and nutrient content. The sum of wheat, rye, and triticale amounted to at least 57% (starter diet) and 63% (grower diet), respectively. The inclusion level of wheat, rye, and triticale was different between experiments, with a maximum rye inclusion of 45%. Five different enzyme preparations all having, 1,4-beta-xylanase as the main activity were considered in this study with either one (2 preparations) or three (3 preparations) levels of supplementation. The effect of enzyme supplementation on ileal digesta viscosity was studied at the end of two experiments comprising 4 enzyme preparations. A significant reduction in digesta viscosity was determined for all preparations. The viscosity of digesta was higher in birds that were fed 45% rye in their diet as compared to those fed a diet based on triticale and wheat, even with enzyme supplementation. Differences in digesta viscosity were not reflected in growth or feed conversion data. In one experiment, the body weight of ducks on day 21 was significantly improved by enzyme supplementation. This effect disappeared with progress in experiment. In another experiment, feed intake was significantly improved with enzyme supplementation. Apart from this, no statistically significant improvement in performance could be detected. On overall average, the final BW of ducks fed an enzyme was (as compared to the unsupplemented control = 100), 100, and the feed conversion ratio was 101. There is no indication from the growth and feed conversion data that an enzyme effect becomes more pronounced with increasing inclusion rate of soluble NSP by rye. It is concluded that supplementary xylanases are efficient in reducing digesta viscosity in ducks fed diets with high inclusion of wheat, rye and triticale. No consistent effect of enzyme supplementation, however, can be expected on growth and feed conversion.

Animal Feed↗
PubMed1995

Endogenous proteolytic enzymes in chicken muscles. Differences among strains with different growth rates and protein efficiencies.

The theory that net muscle growth is, at least partly, regulated by catabolic factors has been tested in order to set up an animal model to study meat aging and post-mortem tenderization. Male and female chickens of a layer strain (White Leghorn), a commercial broiler strain (Ross), and two experimental broiler lines (designated GL and FC) were used to estimate differences in proteolytic enzyme activities in the breast muscles. The GL and the FC lines were selected for high body weight gain and high feed efficiency, respectively. At 6 wk of age the birds were slaughtered and the activities of endogenous proteinases and their specific inhibitors in breast muscles measured. The Leghorns showed significant differences in all traits compared with the three broiler genotypes. Within the broiler types, FC birds tended in the direction of the Leghorns and GL birds in the opposite direction. Ross birds were intermediate between FC and GL birds. All types and sexes differed significantly in slaughtering weight. Feed conversion ratio and protein conversion ratio were highest for Leghorns. The FC birds showed the lowest feed conversion. Ross and GL birds showed intermediate values. The Leghorns showed higher calpain activities and lower calpastatin activity than the three broiler genotypes. The FC broilers showed intermediate calpain and calpastatin activities but higher cathepsin H and total cystatin values. The GL broilers showed lower cathepsin B, D, and H activities. In all cases the Ross broilers showed intermediate values. From these figures it is concluded that the strains of birds used in this study can be used as a natural source of variability to study the mechanisms involved in post-mortem proteolytic degradation and thus in the study of muscle tenderization and meat aging. It is also concluded that it could be very interesting to study the behavior of the different proteolytic systems more carefully in relation to muscular growth characteristics and compare them to anabolic factors involved in muscle growth.

Animals↗
PubMed2006

The relationship between residual feed intake and feed intake behavior in group-housed Duroc barrows.

Because feed is the major input in pork production, conversion of feed into lean tissue at minimum costs has been a focus for improvement. Several researchers have proposed using residual feed intake (RFI) rather than feed conversion ratio (FCR) for genetic improvement of feed efficiency. Little is known about the variation in RFI in pigs. As several studies suggest a greater RFI is related to greater animal activity levels, the current study investigated the phenotypic relationship between RFI and feed intake (FI) behavior of 104 group-housed growing Duroc barrows allowed ad libitum access to feed. Feed intake, BW gain, feeding time (TIME), feeding frequency (VISITS), RFI, and FCR were calculated for 5 periods of 14, 23, 28, 21, or 23 d in length (periods 1 through 5, respectively) on animals that were between 73 to 95 d of age at the start of the testing period. Barrows that grew faster consumed more feed (P < 0.001), and barrows that consumed more feed were fatter (P < 0.01). There were no correlations between VISITS and TIME, between VISITS and FI, or between VISITS and RFI. Barrows that spent more time at the feeder, however, consumed more feed (P < 0.05) and had greater RFI in periods 1, 3, and 5 (P < 0.05). As expected, FI and FCR were highly correlated with RFI (P < 0.001). These results suggest that a greater FI rather than greater feed intake activity resulted in greater RFI values.

Animal Husbandry↗
PubMed1991

Efficiency of feed utilization and rate of feed passage through the digestive system.

The relationship of efficiency of feed utilization determined by the feed conversion ratio (FCR) to the rate of feed passage through the digestive system of juvenile chickens was studied and three different methods of measuring feed passage rate (FPR) were evaluated. The FPR did not differ between sexes that had different FCR, nor did it differ between commercial broiler strains that differed in FCR. Feed restriction did not affect FPR. There was little correlation between FCR and FPR in any of the groups evaluated and the FPR was similar for high- and low-FCR groups. There was some evidence for increased FPR in birds grown at 32.2 C compared with those grown at 26.7 C. Similar results were obtained for FPR whether the tracer dye was given in the feed, or in a gelatin capsule, or no tracer dye was used. Repeatability of FPR obtained on the same individuals at different ages was very low.

Animal Feed↗
PubMed1995

The magnitude of lead toxicity in broiler chickens.

Four experiments were conducted to study the toxic effects of supplemental dietary lead (Pb) on broiler chickens from hatching to 42 d of age. Dietary variables were 0, 0.1, 0.5 or 1.0 mg Pb/kg feed as lead sulfate in Experiment 1, and 0, 0.5 or 1 mg Pb/kg feed as lead sulfate and lead acetate in Experiment 2. Experiments 3 and 4 were 2 x 4 factorial designs with 2 levels of calcium (0.65% or 1.30%) and 4 levels of Pb (0, 1, 10 or 100 mg Pb as lead sulfate/kg feed). Lead supplementation caused linear decreases in body weight gain in all experiments. In Experiments 1, 2 and 4, even 1 mg added Pb/kg feed caused significantly depressed body gains. Significant negative effects of added Pb on feed conversion ratios were found at 10 mg Pb/kg feed. Supplemental Pb caused a linear decrease in delta-aminolevulinic acid dehydratase (ALAD) activity. The higher level of calcium (1.30%) in the feed significantly reduced the negative effects of Pb on ALAD inhibition. Lead additions to the diet resulted in a dose-related increase of Pb in blood, kidney, liver and tibia. Higher dietary calcium caused reduced Pb in blood and liver. Lead is toxic to chickens at much lower levels than previously recognized.

Animal Feed↗
PubMed1988

Broiler performance when reared under various light sources.

Three trials were conducted to determine if modern energy-efficient light sources, which vary in wavelength emission, affect broiler growth performance. The effect of light source on growth performance was determined by measuring body weight, feed conversion, and livability at intervals throughout rearing and at market age in three flocks of approximately 3,600 broilers each. Illuminance within the light-proof experimental facility was approximately 5 1x and photoregimen was 1 h dark:23 h light. Trial 1 compared incandescent (IN), warm white fluorescent (WWF), and daylight fluorescent (DLF) light sources. The WWF source provided superior body weight compared to IN light but feed conversion ratios were similar. Both IN and WWF light sources resulted in better body weight and feed conversion than that of the DLF light source. Trial 2 used IN, WWF, DLF, PL-5 fluorescent (PLF), design white fluorescent (DWF), and high pressure sodium (HPS) light sources. The PLF source resulted in mean body weight significantly higher than those produced by IN, HPS, and DWF. No other significant differences were observed. Trial 3 used IN, WWF, DLF, PLF, HPS, and low pressure sodium (LPS) light sources. Feed conversion for the HPS treatment was superior to that of PLF and LPS treatments. No other significant differences were observed. Light source did not affect livability in any of the trials. These trials demonstrated that energy-efficient light sources varying in wavelength emission may affect broiler growth performance, but consistent differences were not observed. Generally, IN light sources may be replaced with more energy-efficient light sources without adverse effects on broiler growth performance.

Animals↗
PubMed2003

Components of feed efficiency in broiler breeding stock: is improved feed conversion associated with increased docility and lethargy in broilers?.

Two trials were conducted to test the hypothesis that broilers classified as good rather than poor feed converters (low vs. high feed-to-gain ratios, respectively) would show decreased activity (increased lethargy) and reduced fear of human caretakers. In both trials birds were reared to juvenile selection age when the 192 males with the "best" breast and leg conformation were placed into individual bird cages (46 x 60 cm), and their feed conversion ratio (FCR) was measured. In trial 1, birds remained in the cages for 7 d for assessment of feed conversion. During the feed conversion testing period, the birds were subjected to three behavioral tests. First, approach-avoidance responses to a novel object placed in the feeder were observed when feeding would be expected. Second, behavior patterns of individual birds were assessed by recording feeding, drinking, walking pecking, preening, standing, and resting. Third, the 20 birds showing the best FCR and the 20 showing the worst were induced into tonic immobility (TI). Feed conversion was not related to either the novel object or the TI measures of fearfulness. Neither was FCR related to feeding, drinking, walking, or pecking. However, FCR was positively correlated with both standing and preening and negatively correlated with resting behavior. In trial 2, the FCR test lasted for 11 d. The birds were assessed for behavioral patterns (feeding, drinking, walking, pecking, preening, standing, and resting) as in the previous trial. As in trial 1, FCR was positively correlated with standing and negatively correlated with resting behavior. Contrary to expectations, the results of these two studies suggest that broilers with good FCR were actually less lethargic and no more fearful than those that showed poor FCR values.

Animal Feed↗
PubMed2004

Selenium supplementation affects broiler growth performance, meat yield and feather coverage.

(1) Selenium (Se) is an essential part of numerous selenoproteins, most of which are involved in the antioxidant system of the body. It is also required by poultry for the maintenance of optimal health and meat quality. This paper reports data from a study examining the effect of dietary source and concentration of selenium on broiler performance and meat quality. (2) Increased dietary selenium content markedly reduced feed conversion ratio (FCR) as a result of significantly lower feed intakes of birds while maintaining the same weight gains. (3) Selenium supplementation increased feathering, with organic selenium (selenised yeast) being superior to inorganic selenium (sodium selenite). (4) Birds receiving organic selenium in their diets had improved eviscerated weight, breast yield and reduced drip loss. (5) There were significant concentration x source interactions on yields of breasts and marylands (thigh plus drumstick), with elevated levels of organic selenium increasing the yields, whereas the opposite was true for the inorganic selenium.

Animal Nutritional Physiological Phenomena↗