Significant Differences In Feed Conversion Research Articles

THE IMPACT OF THE FREQUENCY OF DIFFERENT FORAGE MIXED WITH GINGER POWDER ON THE PRODUCTIVITY OF KAUR CATTLE

Kaur cattle, Bengkulu's local livestock genetic resources (SDG-T), must be preserved and utilized to increase livestock production. The purpose of this study was to determine the productivity of Kaur cattle through observing the results of feed consumption, daily body weight gain, and feed conversion. For the purpose of this study, twelve Kaur bulls aged 1.5 to two years, weighing between 160 and 180 kilograms were used. Green feed is given by adding ginger flour 1% of body weight and is regulated in the number of times it is given. Cattle feed consists of dry matter as much as 3% of body weight. For this study, the main feed was concentrate and elephant grass (70%: 30%). There were three treatment groups, each with four repetitions. P1 is given once every day at 08.00 am; P2 is administered twice daily at 08.00 am and 12.00 pm; and P3 is given three times every day at 08.00 am, 12.00 noon, and 16.00 pm. Data is evaluated by ANOVA and unidirectional pattern. The results showed that the average daily feed consumption from highest to lowest was P3=9.44±9.50; P2=9.33±9.39; P1=8.87±8.90 kg/head/day. The average daily body weight gain from highest to lowest was P3=1.45±1.49; P2=1.32±1.36; P1=1.12±1.17 kg/head/day. The results show that there is no significant difference between the two. P3=9.19±9.23; P2=9.05±9.10; and P1=8.71±8.79. There was no significant difference in feed conversion from highest to lowest. Consumption of forage and ginger flour at different times did not affect the productivity of Kaur cattle.

Effect of Ration Type During 2- 6 Weeks of Age on Broiler Performance and Carcass Characteristics

This study aimed to investigate the effect of using a grower, finisher, or both rations between 2 - 6 weeks of age on performance and carcass characteristics at 6 weeks of age. 120 Ross 308 unsexed broiler chicks were distributed to three groups with four replicates of 10 birds each. During weeks 0-2, all birds received a starter ration of 3000 kcal/kg ME and 23% CP, During 2-6 weeks T1 received a grower ration of 3100 kcal/kg and 21.5% CP, T2 received a finisher ration of 3200 kcal/kg ME and 19.5% CP, and T3 received a grower ration (2-4) weeks then finisher ration (4-6) weeks. Two birds from each replicate were slaughtered and eviscerated manually for carcass traits. The results showed an insignificant difference in final and weekly body weight except for the first week, and an insignificant total and daily weight gain except for weeks 0-1 and 4-5. Except for weeks 2-3 and 3-4, treatments had no effect on feed intake,T3 had the highest feed intake compared to T1 and T2, there was a significant difference between treatments in protein intake except the first two weeks. There was a significant difference in feed conversion in weeks 0-1 and 4-5, as well as protein conversion in weeks 0-1, 2-3, and 4-5. The differences in all carcass traits and the relative growth rate between treatments were insignificant. T2 showed the best economic efficiency compared to T1 and T3.

Impact of fenbendazole resistance in Ascaridia dissimilis on the economics of production in turkeys

Feed conversion efficiency is among the most important factors affecting profitable production of poultry.Infections with parasitic nematodes can decrease efficiency of production, making parasite control through the use of anthelmintics an important component of health management. In ruminants and horses, anthelmintic resistance is highly prevalent in many of the most important nematode species, which greatly impacts their control. Recently, we identified resistance to fenbendazole in an isolate of Ascaridia dissimilis, the most common intestinal helminth of turkeys. Using this drug-resistant isolate, we investigated the impact that failure to control infections has on weight gain and feed conversion in growing turkeys. Birds were infected on D 0 with either a fenbendazole-susceptible or -resistant isolate, and then half were treated with fenbendazole (SafeGuard Aquasol) at 4- and 8-wk postinfection. Feed intake and bird weight were measured for each pen weekly throughout the study, and feed conversion rate was calculated. Necropsy was performed on birds from each treatment group to assess worm burdens at wk 7 and 9 postinfection. In the birds infected with the susceptible isolate, fenbendazole-treated groups had significantly better feed conversion as compared to untreated groups. In contrast, there were no significant differences in feed conversion between the fenbendazole-treated and untreated groups in the birds infected with the resistant isolate. At both wk 7 and 9, worm burdens were significantly different between the treated and untreated birds infected with the drug-susceptible isolate, but not in the birds infected with the drug-resistant isolate. These significant effects on feed conversion were seen despite having a rather low worm establishment in the birds. Overall, these data indicate that A. dissimilis can produce significant reductions in feed conversion, and that failure of treatment due to the presence of fenbendazole-resistant worms can have a significant economic impact on turkey production. Furthermore, given the low worm burdens and an abbreviated grow out period of this study, the levels of production loss we measured may be an underestimate of the true impact that fenbendazole-resistant worms may have on a commercial operation.

Effects of replacing different proportions of barley grain by rye grain on performance of growing and finishing dairy bulls

The objective was to study the effects of partial replacement of barley grain by rye grain on dry matter (DM) intake and growth performance of growing bulls. The experiment was conducted using 80 dairy bulls which were fed total mixed rations ad libitum. The rations included grass silage (500 g kg-1 DM) and concentrate (500 g kg-1 DM). Four different experimental concentrate mixtures included rye at 0, 150, 300 and 450 g kg-1 DM. The average daily DM and metabolisable energy intakes of the bulls were 10.9 kg d-1 and 127 MJ d-1, respectively. There were no differences in DM, energy or nutrient intakes among the treatments. The average live weight gain and carcass gain of the bulls were 1543 and 832 g d-1, respectively, and rye inclusion had no effects on growth. There were no significant differences in feed conversion or carcass characteristics among the treatments. It can be concluded that rye grain is a suitable energy supplement with good quality silage for growing dairy bulls.

Impact of Betaine Supplementation on the Growth Performance, Tonic Immobility, and Some Blood Chemistry of Broiler Chickens Fed Normal and Low Energy Diets During Natural Summer Stress

The current study was conducted to investigate the effect of graded levels of betaine supplementation to the normal and low energy diets of broiler chickens during summer season on growth performance, tonic immobility (TI), economic value and some blood biochemical parameters. Three hundred one days-old broiler chicks were used. The chicks were divided into 6 groups (each of 50 chicks) and each group was 5 replicated (2x3 factorial design). The first, second and third groups were fed normal energy diet (NED) with 0, 1 and 2g betaine/kg diet (air dry basis) for 35 days, respectively. While, the fourth, fifth and sixth groups were fed low energy diet (LED) with 0, 1 and 2g betaine/kg diet (air dry basis) for 35 days, respectively. The experiment was carried out during summer season. Birds freely access to water and feed. Results showed no significant difference of growth performance between NED and LED groups. Betaine supplementation (2g/kg diet) to both NED and LED increased significantly (p<0.05) the body weight (BW) (1880.61 and 1787.66g, respectively), body weight gain (BWG) (1822.22 and 1728.77g, respectively), feed intake (FI) (3027.36 and 3136.42g, respectively), relative growth rate (RGR) (187.93 and 187.24, respectively) and TI (92.83 and 71.83s, respectively) with no significant difference in feed conversion (FCR) between the groups fed diet supplemented with or without betaine. Betaine supplementation 2g/kg diet to NED increased the total cost, total return, net profit, economic efficiency and performance index%, moreover improved the pancreatic and thyroid function and return the lipids indices of LED-fed birds to the normal level as in the NED-fed birds. No mortalities occur between the different groups. Therefore, betaine can be included in normal energy diets of broiler chickens by level of 2g/kg diet for improving the growth performance, economic value and welfare during the summer season.

&lt;b&gt;Growth performance and intestinal histomorphology of Nile tilapia juveniles fed probiotics&lt;/b&gt; - doi: 10.4025/actascianimsci.v35i4.18610

The objective of this study was to assess the growth performance and the histomorphometric characterization of the middle intestine of GIFT strain Nile tilapia, Oreochromis niloticus juveniles fed probiotics, added either before or after the feed processing. The experimental design was completely randomized, with five treatments and five replications: pelleted feed without any probiotic; pelleted feed with inclusion of probiotic before the processing; pelleted feed with inclusion of probiotic after the processing; extruded feed without any probiotic and extruded feed with inclusion of probiotic after the processing. Two hundred and fifty juveniles were distributed in 25 aquaria (20L) and fed for 63 days. Differences in the mean values of total weight were found at the end of the experiment. After 42 days of feed intake, significant differences in feed conversion were verified for treatments with extruded diets when compared to the pelleted ones. The fishes fed diets supplemented with probiotic presented increase in the thickness of the epithelium of the intestine. The best zootechnical performance was observed in the extruded diet supplemented with probiotic added after the feed processing. The inclusion of 4.0 x 108 CFU g-1 of Bacillus subtilis and 4.0 x 108 CFU g-1 of Bacillus toyoi in both the pelleted and the extruded diets promoted an increase in the thickness of the epithelial layer of the middle intestine.

Evaluation of Nupro® Yeast Product in Diets for Broilers

Two trials with identical experimental design were conducted approximately 20 months apart to evaluate the response of broiler chickens to the addition of NuPro®, a yeast product rich in nucleotides. In both trials, four dietary treatments were compared. The first treatment contained no NuPro®. For the second treatment, the diet with 2% NuPro® was fed only the first 7 days of life while for the third treatment, 2% NuPro® was fed for the first 14 d. For the fourth treatment, 2% NuPro® was fed for the first 7 days and also during the finisher period of 35-42 d of age. In both studies, each treatment was fed to six replicate groups of 60 male broilers of a commercial strain. Response to the addition of NuPro® varied between the two experiments. In the first study, addition of 2% NuPro® to the diet resulted in improvement in feed conversion. Response varied by age of bird and time during which the NuPro® was fed. At 7 d of age, there were no significant differences between birds that had been fed NuPro® and those fed the negative control diet. At 14 d of age, there were no significant differences in feed conversion among birds fed the various treatments, but feed conversion was numerically better for those birds that had been fed NuPro® for the first 7 or 14 d. At 35 d, birds that had been fed NuPro® for the first 7 d had significantly better feed conversion than those fed the control diet with birds fed NuPro® for the first 14 d being intermediate between these two groups. At 42 d, birds fed diets with 2% NuPro® for the first 7 d or for the first 7 d followed by feeding from 35-42 d had significantly lower feed conversion than those fed the control, with those fed NuPro® for the first 14 d being intermediate between these groups. However, in the second trial there was no significant effect of inclusion of NuPro on any of the parameters evaluated. There may be nutritional differences between batches of the product that influence the response of chicks.

Productos de papel como material de carnada de pollos de engorde: desempeño productivo, defectos de la canal y lesiones del cojín de las patas.

Se evaluó el uso de productos de papel reciclado como material para carnada de pollos parrilleros y sus efectos sobre el crecimiento, desempeño productivo y lesiones en las patas. Se criaron 168 pollos parrilleros hasta la edad de mercado (42 d) en un galpón con laterales abiertos localizado en la Granja Experimental para Animales Pequeños de la Estación Experimental Agrícola de Lajas. Las aves se asignaron a 12 jaulas de piso con carnada de cascarilla de arroz (CDA) como control; una mezcla 50:50 de CDA y papel blanco triturado (PBT); o una mezcla 50:50 de CDA y papel de periódico triturado (PPT) en un diseño completamente aleatorizado repetido cuatro veces. Se evaluó el peso corporal, consumo de alimento, conversión alimenticia, rendimiento de la canal, laceraciones de la pechuga, quemadura del cojín de la pata y la mortalidad. El porcentaje de humedad de la carnada se determinó a los 14, 28 y 42 d de edad. El material utilizado como carnada no afectó el peso corporal, consumo de alimento, laceraciones de la pechuga ni la mortalidad de las aves. Sin embargo, los pollos criados en PBT mostraron un menor consumo de alimento y un mayor peso corporal al compararse con aquellos criados en CDA y PPT. No se observaron diferencias significativas en la conversión de alimento de los siete a los 28 d de edad. A los 35 y 42 d, los pollos criados en PBT mostraron una menor conversión de alimento que las aves criadas en CDA, mientras que la conversión de alimento de los pollos criados en PPT fue similar a la de los demás tratamientos. No se encontraron diferencias en el rendimiento de la canal entre los tratamientos estudiados. En todos los periodos de muestreo, el porcentaje de humedad de la carnada fue significativamente mayor en PPT que en las demás carnadas. No se observaron problemas de áreas húmedas en ninguna de las carnadas estudiadas. Se observaron diferencias significativas en quemaduras del cojín de las patas, siendo la incidencia mayor en los pollos criados en PPT, menor en CDA e intermedia en aquellos criados en PBT. Los resultados sugieren que los productos de papel reciclado pueden ser una excelente alternativa como material de carnada para el levante de pollos parrilleros. La utilización de PBT aparenta mejorar el desempeño productivo y reducir la incidencia de quemaduras del cojín de las patas.

Comparison of Normal and High Available Phosphorus Corn With and Without Phytase Supplementation in Diets for Male Large White Turkeys Grown to Market Weights

Large White turkeys were fed diets containing either normal yellow dent corn (YDC) or a corn mutation containing low phytate phosphorus and high available phosphate corn (HAPC). Diets were considered nutritionally adequate in all respects with various degrees of reduction in available phosphorus content ( - 0.0, - 0.05, - 0.10 or - 0.15% of NRC (1994) recommendations for different feeding periods). These diets were fed with or without the addition of 1000 U/kg of phytase enzyme (Natuphos , BASF), resulting in ® a total of 16 dietary treatments. Each treatment was assigned to three pens of 20 male turkeys from day-old to 20 wk of age. Body weight, feed consumption, and tibia ash were determined at 28 d intervals during the study. Male turkeys fed diets with HAPC did not differ significantly in BW or feed conversion (FC) from those fed diets with YDC, and had significantly higher tibia ash at 4, 8, and 12 wk of age. Addition of 1000 U/kg of phytase resulted in significantly higher BW at 4, 8, 12, and 16 wk of age as compared to unsupplemented controls with no significant differences in FC. The addition of phytase significantly improved tibia ash at every age. Dietary phosphorus content had no effect on BW or FC at any age. Reduction of phosphorus generally did not impair tibia ash until reduction of 0.15% below NRC (1994) recommendations. Addition of phytase aided in overcoming the reduction in phosphorus content. The combination of HAPC, addition of phytase, and reduction in dietary phosphorus content should aid in reducing phosphorus excretion without impairing performance.

Effects of Concentrate Level on Carcass Composition, Tenderness and Growth Rate of Angus × NRF and Limousin × NRF Bulls

In total, 56 bulls of Angus 2 NRF or Limousin 2 NRF were fed two levels (either 2.5 or 5.0 kg animal -1 day -1 ) of concentrate from 12 weeks of age to slaughter in a 2 2 2 factorial design with cross-breed and concentrate level as fixed factors. The concentrate was a mixture with barley, oats, wheat, soyabean and molasses as main components. In addition, the animals had ad libitum access to grass silage. As expected, the bulls fed the high concentrate diet had higher growth rate than bulls fed moderate level of concentrate. Angus 2 NRF bulls fed the high level of concentrate showed the highest growth rate of the four subgroups and were on average slaughtered at the age of 15 months. Limousin 2 NRF bulls fed the moderate level of concentrate were the subgroup with the lowest growth rate and needed 20 months to reach the target slaughter weight, which on average was 280 and 340 kg for Angus 2 NRF and Limousin 2 NRF, respectively. Although the animals at the high concentrate level had a greater intake of energy day -1 , there was no significant difference in feed conversion calculated as FUm kg -1 gain between the subgroups. The Limousin cross-breeds had significantly higher relative proportions of muscle in the carcass, but less bone and fat than the Angus cross-breeds. Consequently, the Limousin 2 NRF bulls achieved better muscularity grading in the EUROP system than the Angus 2 NRF bulls. Concentrate level yielded different fatness scores in the EUROP system, while breed did not. The correlation between carcass weight and psoas major or longissimus dorsi muscles was stronger for the former muscle. There was a tendency for Angus 2 NRF bulls fed the moderate concentrate level to have more tender longissimus muscle than the other subgroups, but this difference was not significant.

The dietary protein and lipid requirements of post-puerulus western rock lobster, Panulirus cygnus

The dietary requirements of post-puerulus western rock lobster for protein and lipid (fat) were examined in a 6-week, pair-fed feeding study. Incremented dietary amounts of protein (30%, 35%, 40%, 45%, 50% and 55%) at each of two dietary fat levels (6% and 10%) were examined. An additional diet of fresh mussels ( Mytilus edulis) was included as a reference. At the end of the 6-week growth experiment, growth of the rock lobsters was better when protein levels were greater than 50% of the diet. Growth of rock lobsters was also significantly greater in diets with the lower fat levels. The growth of the animals fed the reference diet was significantly superior to all of the experimental diets. Survival of animals in all treatments was equal to or greater than 75%. Though there were some significant differences in survival among treatments, this was not consistent with any relationship between either protein or fat content of the diets. The number of moulting events observed in each of the test treatments was significantly lower than that observed by the mussel-fed animals. This was consistent with what was observed with the level of growth difference among the test treatments and the mussel-fed treatment. There were no significant differences in the number of moulting events among any of the protein-lipid level treatments. There were no significant differences among the test treatments with feed intake on a proportion of body weight basis. This was in accordance with the pair-feeding protocol of this study. Feed conversion by the lobsters in each of the test treatments was in accordance with what was observed in their corresponding growth responses. Diets containing 6% fat and either 50% or 55% protein had significantly lower FCR values than all other test diets (2.7:1 and 2.5:1, respectively). The diet that had 10% fat and 30% protein had the highest FCR (7.6:1) and was significantly higher than all other diets. There were no other significant differences in feed conversion among the test treatments. The results of this study support that post-puerulus Panulirus cygnus have a very high dietary protein requirement and a poor capacity to utilise dietary lipid. It should be noted though that the relative growth of the post-puerulus P. cygnus fed the pelleted diets was considerably lower than of those fed the reference diet of fresh mussels. Accordingly, optimal diets derived from this study should be based on fat levels of about 6% and protein levels equal to or exceeding 55%.

Effects of different concentrations of monensin and monensin withdrawal upon the control of coccidiosis in the turkey

The efficacy of different concentrations of monensin in turkeys exposed to field isolates of Eimeria and the effect of the withdrawal of monensin from their diet were investigated. Results of a battery study indicated that 66 ppm monensin was effective against three species of Eimeria in the turkey. In floor pens in which poults were exposed to infection, use of 59.5, 79.4, and 99.2 ppm monensin resulted in reduced mortality and improved feed conversion at 3 wk of age compared with birds that had received no medication. Poults given 59.5 ppm monensin weighed more and had a better feed conversion at 3 wk than poults given 79.4 or 99.2 ppm monensin, but at 10 wk no differences in the body weight or feed conversion of poults given different concentrations of drug were apparent. At 14 wk (and from 10 to 14 wk), poults that had been given 99.2 ppm monensin had a lower feed intake and weighed less than birds that had been given 59.5 ppm of the drug but there were no significant differences in feed conversion. There was no significant difference in the weight gain or feed conversion of poults from 10 to 14 wk of age whether monensin was present in the feed or had been withdrawn. No evidence of compensatory growth was found in the present study.

Dietary protein concentration and daily feed allowance influence response of channel catfish, Ictalurus punctatus (Rafinesque), to ractopamine

Year-1 channel catfish, Ictalurus punctatus (Rafinesque) (average initial weight, 48 g) were fed diets containing 240 g kg−1, 300 g kg−1, or 360 g kg−1 dietary protein with 0 or 20 mg kg−1 ractopamine to satiation and diets containing 240 g kg−1 and 360 g kg−1 protein with 0 or 20 mg kg−1 ractopamine at a restricted rate (60% of satiation) in aquaria at 29 ± 2°C for 8 weeks. Fish fed ractopamine at the 360 g kg−1 protein level gained significantly more weight than controls when fed to satiation but not when the ration was restricted. Fish fed ractopamine at the 240 g kg−1 protein level did not gain more weight than the controls at satiation or restricted feeding. Fish fed ractopamine in the diet containing 300 g kg−1 protein gained significantly more weight than controls when fed to satiation. Ractopamine caused no significant differences in feed conversion at the 240 g kg−1 or 360 g kg−1 protein levels with restricted or satiation feeding. Muscle fat decreased when ractopamine was fed at all dietary protein levels and at both feeding rates. Muscle protein increased with ractopamine feeding in all treatments except the high-protein, satiation treatment. Weight gain response of year-1 channel catfish to ractopamine is dependent upon nutrient concentration of the diet and ration size; however, the effect of ractopamine on muscle composition of channel catfish is less dependent on nutrient concentration or amount of diet fed.

Two Housing Systems for Intensively Reared Bulls Slaughtered in Two Weight Ranges

Abstract 510 group-fed bulls of the Swedish Red and White breed were used to investigate differences in production and health when housed either in an insulated building with slatted floors in the pens or in an uninsulated building with partly littered pens. Two stocking densities, 11 versus 15 animals/pen, were studied as well, but only in the uninsulated building. The animals were fed concentrate ad lib., 0.5 kg/d of roughage, and were slaughtered at about 220 kg live weight (bull calves) or at about 420 kg live weight (bulls). The comparison between buildings showed no significant differences either in feed intake or in live weight gain. Feed conversion, if calculated as MJ metabolizable energy/kg live weight gain, was significantly poorer for bull calves (but not for bulls) in the uninsulated building. If calculated as MJ metabolizable energy/kg carcass gain, there was no significant difference in feed conversion between animals in different buildings. Animals in the uninsulated building had less fat in the carcass than the others. Bull calves had significantly more liver abscesses in the insulated building than in the other. Bulls were treated for pneumonia and interdigital phlegmon more often in the uninsulated than in the insulated building. Animals in the uninsulated building had a higher energy requirement for maintenance and activity than the others. The main reason for this was probably the difference between buildings in area per animal and pen design. The higher stocking density resulted in a lower growth rate of the bulls.

Incorporation of microbiologically treated spent brewery grains into broiler rations

The cellulolytic fungus Trichoderma reesei QM9414 was cultivated on spent brewery grains to partially hydrolyse the grains into soluble sugars and to alter the amino acid profile of the substrate. Aflatoxins were not detected in either the treated or the untreated spent grains. Amino acid profiles indicated that both the untreated and partially hydrolysed spent grains possess the entire range of essential amino acids required by poultry. Treated grains contained higher levels of lysine, histidine, glycine, methionine, phenylalanine, proline and alanine compared to those in untreated grains. The incorporation of treated grains at 8% and 12% into starter rations for broiler chickens in the first 4 weeks resulted in significant improvement in their growth and feed conversion ratio. There was no significant difference in feed conversion after 6 and 8 weeks of growth.

Diet Regimes for Growing Guineas as Meat Birds

Growing guineas were fed three diet regimes with the control regime based on reports of French studies. The experimental diets were either 10% above or below the control diet in protein, lysine, and total sulfur containing amino acids. Keets fed the higher nutrient density diet weighed significantly more at 12 weeks of age (1084 g) than those on the control diet (1041 g) but there were no significant differences in feed conversion. These data suggest that the starter diet for keets should contain at least 21% protein and the finisher diet should contain at least 17% protein.

PERFORMANCE OF DWARF BROILER BREEDERS IN LAYING CAGES AND FLOOR PENS AND OF NORMAL BREEDERS IN FLOOR PENS

Dwarf broiler breeders in single-bird cages (DC), in floor pens (DF) and normal broiler breeders in floor pens (NF) were compared for their own and their offspring’s performance. No differences were observed in rate of egg production at 147–329 days of age between the NF and DF birds (48 vs. 47%) whereas the DC birds laid at the rate of 40%. Hen-housed egg numbers for the same period followed the same general pattern (NF, 81; DF, 82; DC, 70 eggs/bird). DF and DC birds consumed less feed per dozen eggs than the NF birds (3.4 vs. 4.3 kg/doz). Egg weights in the early part of the production cycle were not significantly different among the groups but at 294 days of age the normal birds laid larger eggs than the dwarfs (65 vs. 62 g). Dwarfs in cages reached 50% production earlier than the DF or NF birds. Female offspring from the three groups grew at the same rate and weighed 1.7 kg at 56 days of age but there were significant differences in feed conversion (NF, 2.46; DF, 2.43; DC, 2.53 kg/kg body weight produced). Male offspring had small but not statistically significant differences in body weight at 56 days (NF, 2.16; DF, 2.12; DC, 2.09 kg) or feed conversion (NF, 2.30; DF, 2.29; DC, 2.34 kg/kg body weight). Mortality in the offspring ranged from 2.7 to 9.2% but did not differ significantly. Income over feed costs per broiler started did not differ from the three groups regardless of the meat price – feed price combination considered. However, when profit was computed on a breeder hen basis, the DF females were more profitable than either the NF or DC females.

Candida ingens as a potential fodder protein.

Pig wastes were fermented and the supernatant was inoculated at the surface with Candida ingens which grew as a pellicle. This was harvested, dried and incorporated with wheat into 2 rations of 20% and 17.9% crude protein as were 2 similar rations using casein and wheat. Using rats the rations were compared for 43 d. There was no significant difference in weight gain or feed conversion between the yeast and casein fed rats at 20% crude protein nor was there a difference in weight gain at 17.9% crude protein; there was a significant difference in feed conversion at 17.9% crude protein (P less than .05). Rats fed C. ingens showed no abnormality at autopsy.

Influence of Genetic Differences in Feed Efficiency of Young Chickens on Derivation of Metabolizable Energy from the Diet and Nitrogen Retention

The relationship of efficiency of efficiency of feed utilization with metabolizable energy derived from the diet and nitrogen retention was studied in broiler strains and in lines selected for divergence in feed conversion ratio. Individual feed conversion (g feed/g gain) and metabolizable energy derived from the diet and nitrogen retention (determined by chromic oxide method) of these strains and lines were measured, and correlations were determined at various intervals from 4 to 9 weeks of age to determine the effects of age, sex, strain, feed conversion, growth, and feed consumption on the metabolizable energy derived from the diet and nitrogen retained. Although there were significant differences in feed conversion between sexes, strains, and lines selected for divergence in feed conversion, there were no associated differences in metabolizable energy derived from the diet or in nitrogen retention. There were no significant correlations of consumption, growth, or feed conversion with metabolizable energy derived from the diet or nitrogen retention. Nitrogen retention of the White Plymouth Rock strain was significantly higher for all ages. These results show that differences observed in growth, consumption, or feed conversion do not influence derivation of metabolizable energy from the diet or nitrogen retention.

The Effects of Egg Weight on Subsequent Broiler Performance

INTRODUCTIONINVESTIGATIONS concerning the relationship of egg weight and subsequent performance of broilers to various ages have led to conflicting reports.O’Neil (1950), working with Barred Plymouth Rocks, concluded that those chicks hatching with the highest percentage of the original weight of the egg are heavier at eight weeks of age, more efficient in feed consumption and have a lower rate of mortality. Wiley (1950) likewise concluded that a positive trend in body weight and livability existed in favor of birds from large eggs. Although this trend was not statistically significant, he did find significant differences in feed conversion in favor of birds hatched from larger eggs. Any advantage in favor of birds from large eggs was usually overcome by twelve weeks of age as evidenced by the reduction in magnitude of the correlations between egg size and chick weight from 3–12 weeks of age. That chicks from large…