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Two experiments were conducted to evaluate metabolism and rumen fermentation responses of lambs fed either monensin or lasalocid (33 mg/kg level) in an alfalfa-corn diet. Experiment 1 was a lamb metabolism trial where rumen samples were taken at the end of each excreta collection period. In Exp. 2, ruminally cannulated sheep were used and cotton thread cellulose and soybean nitrogen (N) disappearance were measured by the in situ dacron bag technique. Rumen turnover rates and volatile fatty acid (VFA) and ammonia pool sizes were determined. In Exp. 1, dry matter and fiber (neutral detergent fiber, NDF; acid detergent fiber, ADF and hemicellulose) digestibilities were not influenced by treatment. Absorbed N was increased (P less than .05) with lasalocid, but not with monensin. No direct or adaptive rumen effects on in situ cellulose or N disappearance were noted in Exp. 2 for either additive. In Exp. 1, at 6 h postfeeding, both additives increased (P less than .05) propionate concentration and lowered (P less than .05) the acetate: propionate (A:P) ratio, while only monensin decreased (P less than .05) rumen ammonia levels. However, no differences in ammonia or VFA concentrations were noted at 2 and 4 h postfeeding. In Exp. 2, where pool size was considered, monensin-fed sheep had lower (P less than .05) total quantities of rumen ammonia at 8 and 12 h postfeeding. Both additives decreased A:P ratios at 6 and 12 h. Lasalocid increased (P less than .05) acetate, propionate and total VFA pool size at 12 h.

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Four experiments were conducted to evaluate the inclusion of fiber from various sources and of various particle sizes in both semipurified and corn-soybean meal diets fed to chicks. Growth rate and feed efficiency were the performance measurements tested. In Experiment 1, 8-day-old New Hampshire X Columbian female chicks were fed polyethylene (PE) and alfalfa cell walls (ACW) of varying particle sizes (<300 Mm, 300 to 600 Mm, and 600 to 1200 Mm), incorporated into diets at the 8% level. A 0% fiber and an 8% solka floe treatment were used as controls. Consumption of ACW resulted in higher (P<.05) growth rates (6.5 vs. 5.4 g/day) and better (P<.05) feed efficiencies (.46 vs. .41) compared with chicks fed PE, regardless of particle size. In Experiment 2, two levels (4 and 8%) of pectin, lignin and xylose:gum arabic (50:50 mix), were tested using 8-day-old chicks of the same strain. Both levels of lignin and xylose:gum arabic (50:50 mix) resulted in superior grains compared to chicks fed control diets, while 8% pectin resulted in lower (P<.05) growth rates (3.3 g/day) than controls (5.2 g/day). Feed efficiencies followed the same pattern as growth rate. In Experiments 3 and 4, 1-day-old chicks (Experiment 3) and 8-dayold chicks (Experiment 4) of the Hubbard strain were fed two levels (5 and 10%) of gum arabic, xylose, and lignin substituted for corn in practical-type diets. Controls included 0% fiber and 5% arenaceous flour treatments. In Experiment 3, chicks fed both levels of xylose and lignin gained better (P<.05) than controls, whereas those fed 5% gum arabic performed poorer (12.3 g/day for controls; 9.6 g/day for gum arabic). Feed efficiency results showed similar trends. Growth rates of 8-day-old chicks fed 10% gum arabic and 10% xylose were lower (P<.05) than controls (28.4 and 30.7 vs. 31.6 g/day, respectively). Only chicks fed 10% gum arabic had lower feed efficiencies than controls. Cecal and large intestinal contents from chicks fed 10% xylose contained the highest concentration of volatile fatty acids (VFA) (83.5 and 79.9 Mmoles/ml). Chicks fed lignin had the least cecal VFA (60.8 Mmoles/ml) while chicks fed lignin and those fed the control diet had the least large intestinal VFA. Acetate was the predominant VFA while propionate was present in the lowest molar concentration. (

We investigated the effects of replacing dietary starch with dietary fibers of various types and particle sizes on utilization of bivalent cations by chicks. Inclusion of polyethylene powder, alfalfa cell walls, corn bran, oat bran and wheat bran into diets resulted in lower serum and tibia Zn levels. However, addition of pectin, cellulose and a xylose:gum arabic (50:50) mixture did not affect tissue Zn levels, whereas addition of 4% lignin increased serum Zn level from 2.50 to 3.44 micrograms/ml. Ingestion of fibers with particle sizes less than 300 micrometers resulted in higher serum Zn levels compared with those of particle sizes greater than 300 micrometers. Incorporation of 4 and 8% pectin decreased (P less than 0.05) serum and tibia Mg levels. When brans were fed, kidney Mg levels were lower due to fiber additions. Inclusion of lignin, the xylose:gum arabic mixture and alfalfa cell walls resulted in lower liver Cu levels; polyethylene and solka floc had no effect on liver Cu status. Fiber did not affect tissue Ca or Fe status. Each mineral influenced by fiber type, level or particle size appeared to be affected through different mechanisms.

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Effects of low-density broiler breeder diets on offspring performance and mortality were studied using 2,100 female and 210 male Cobb 500 breeders. Breeder treatments involved 4 experimental groups and a control group with normal density diets (ND, 2,600 kcal of AME/kg during rearing and 2,800 kcal of AME/kg during laying). In treatment 2, nutrient densities were decreased by 12% (LD12) and 11% (LD11) during the rearing and laying periods, respectively, whereas in treatment 3, nutrient densities were decreased by 23% (LD23) and 21% (LD21) during the rearing and laying periods, respectively. The nutrient density in these treatments was decreased through inclusion of palm kernel meal, wheat bran, wheat gluten feed, and sunflower seed meal in the diets. Treatment 4 included diets with the same nutrient densities as in treatment 2 but included oats and sugar beet pulp (LD12(OP) and LD11(OP)). In treatment 5, the same low-density diet was given to the breeders as in treatment 2 during the rearing period, but it was followed by a normal density diet during the laying period (LD12-ND). Treatments were applied from 4 to 60 wk of age. On low-density diets, offspring showed an increased 1-d-old weight. As compared with offspring of breeders that received ND, the d 38 live weight of chickens from 29-wk-old breeders fed LD11 was improved. Mortality was reduced in offspring from 60-wk-old parent stock given low-density diets. The IgM titers in 35-d-old offspring from eggs with a lower-than-average weight were reduced when 29-wk-old broiler breeders were fed low-density diets. In offspring from eggs with a higher-than-average weight from 60-wk-old parent stock given LD11 or LD21 diets, IgM titers were higher compared with ND. It was concluded that low-density broiler breeder diets can improve offspring growth rates, reduce mortality, and reduce or increase immune responses, depending on breeder age and egg weight.

The effect of low-density diets on bird performance, egg composition, and embryonic development was studied with 2,100 female and 210 male Cobb broiler breeders from 25 to 60 wk of age. The experiment included 5 treatments. These included a control group with a normal density diet (ND, 2,800 kcal of AME/kg). Treatments 2 (LD11) and 3 (LD21) had a 11 and 21% lower nutrient density. Treatment 4 (LD11(OP)) had a 11% less dense diet, which was obtained by inclusion of other feed ingredients. In these 4 treatments similar diets were given during the rearing and the laying period. Treatment 5 combined LD12 in the rearing period and ND diets during the laying period (LD12-ND). Egg composition and embryonic development were measured in eggs of ND and LD21 birds at 29 and 41 wk of age. During the laying period from wk 25 to 60, live weights did not differ among treatments, except that birds fed LD11(OP) had lower live weights. A significantly higher rate of lay was provided by LD11 compared with ND. Egg weights were significantly higher when low-density diets were fed, particularly in LD11(OP). Percentage of fertile eggs did not differ among treatments. Compared with the other treatments, LD11(OP) provided a significantly lower hatchability. We found that LD21 resulted in a better development of the area vitellina externa and heart and embryo weight at 29 wk of age. It was concluded that this was related to a higher egg weight and egg white proportion. This suggests that the amount of egg white in eggs of hens fed ND was limiting for embryonic development, particularly in eggs of young broiler breeders.