K. J. Hanford

Estimates of genetic parameters and genetic change for reproduction, weight, and wool characteristics of Targhee sheep

Genetic parameters from both single-trait and bivariate analyses for prolificacy, weight, and wool traits were estimated using REML with animal models for Targhee sheep from data collected from 1950 to 1998 at the U.S. Sheep Experiment Station, Dubois, ID. Breeding values from both single-trait and seven-trait analyses calculated with the parameters estimated from the single-trait and bivariate analyses were compared across years of birth with respect to genetic trends. The numbers of observations were 38,625 for litter size at birth and litter size at weaning, 33,994 for birth weight, 32,715 for weaning weight, 36,807 for fleece weight and fleece grade, and 3,341 for staple length. Direct heritability estimates from single-trait analyses were 0.10 for litter size at birth, 0.07 for litter size at weaning, 0.25 for birth weight, 0.22 for weaning weight, 0.54 for fleece weight, 0.41 for fleece grade, and 0.65 for staple length. Estimate of direct genetic correlation between litter size at birth and weaning was 0.77 and between birth and weaning weights was 0.52. The estimate of genetic correlation between fleece weight and staple length was positive (0.54), but was negative between fleece weight and fleece grade (-0.47) and between staple length and fleece grade (-0.69). Estimates of genetic correlations were near zero between birth weight and litter size traits and small and positive between weaning weight and litter size traits. Fleece weight was slightly and negatively correlated with both litter size traits. Fleece grade was slightly and positively correlated with both litter size traits. Estimates of correlations between staple length and litter size at birth (-0.14) and litter size at weaning (0.05) were small. Estimates of correlations between weight traits and fleece weight were positive and low to moderate. Estimates of correlations between weight traits and fleece grade were negative and small, whereas estimates between weight traits and staple length were positive and small. Estimated breeding values averaged by year of birth from both the single- and seven-trait analyses for the prolificacy and weight traits increased over time, whereas those for fleece weight decreased slightly and those for the other wool traits were unchanged. Estimated changes in breeding values over time did not differ substantially for the single-trait and seven-trait analyses, except for traits highly correlated with another trait that was responding to selection.

Effect of corn processing method and corn wet distillers grains plus solubles inclusion level in finishing steers

Two experiments were conducted to determine the effect of corn processing method and corn wet distillers grains plus solubles (WDGS) level on steer performance and metabolism. In Exp. 1, 480 crossbred steer calves (314 +/- 18 kg of BW) were used in a finishing experiment with a randomized complete block design and a 3 x 4 treatment structure. Diets were based on dry-rolled (DRC), high-moisture (HMC), or steam-flaked corn (SFC) with increasing levels of WDGS (0, 15, 27.5, or 40%; DM basis). A corn processing x WDGS level interaction (P < 0.01) was observed for ADG and G:F. Average daily gain and G:F increased linearly (P < 0.01) in steers fed DRC; ADG increased quadratically (P = 0.04) and G:F increased linearly (P = 0.02) in steers fed HMC; and ADG decreased quadratically (P = 0.02) with no change in G:F (P = 0.52) in steers fed SFC as WDGS increased. In Exp. 2, 7 ruminally fistulated steers (440 +/- 41 kg of BW) were used in a 6-period crossover design with 3 x 2 factorial treatment structure. Diets were the same as those fed in Exp. 1, except they contained only 2 levels of WDGS (0 or 40% of diet DM). Total tract starch digestibility was greater (P < 0.01) for steers fed SFC than for steers fed DRC or HMC. Minimum ruminal pH was less (P < 0.01) for steers fed SFC than for steers fed HMC or DRC. Variance of ruminal pH was different among all 3 processing methods with DRC < HMC < SFC (P < 0.10). In situ 22-h DM digestibility of DRC and HMC and starch digestibility of DRC were greater (P < 0.10) in steers fed DRC compared with steers fed HMC or SFC. Steers fed 0% WDGS had less (P < or = 0.02) intake of DM, OM, NDF, and ether extract compared with steers fed 40% WDGS. Total tract digestibility of DM and OM was greater (P < or = 0.08) and digestibility of ether extract tended (P = 0.11) to be less for steers fed 0% WDGS compared with steers fed 40% WDGS. Maximum ruminal pH and pH variance were greater (P < or = 0.08) in steers fed 0% WDGS. A corn processing x WDGS level interaction (P = 0.09) was observed for ruminal acetate to propionate ratio (A:P). Within diets containing 0% WDGS, A:P in steers fed SFC was less (P < or = 0.08). In diets containing 40% WDGS, A:P was similar between processing methods and not different from the SFC with 0% WDGS. The corn processing x WDGS level interaction observed in the finishing experiment may be due to the decreased ruminal A:P in DRC and HMC diets with 40% WDGS.

Dried distillers grains with solubles in laying hen diets

A study was conducted to test the inclusion rate of corn dried distillers grains with solubles (DDGS) in laying hen diets on egg production (EP) responses for a full production cycle. A total of 288 Bovan Single Comb White Leghorn laying hens were fed diets containing 0, 5, 10, 15, 20, or 25% DDGS from 24 to 46 wk (phase 1) and 47 to 76 wk (phase 2) of age. The diets were formulated to be isocaloric at 2,775 and 2,816 kcal/kg of ME and isonitrogenous at 16.5 and 16.0% CP for phases 1 and 2, respectively. Nutrient retention of both N and P were determined by the indicator methods during phase 2. Diets were replicated with 8 pens/treatment and 6 hens/pen in an unbalanced randomized complete block design. Average daily feed intake, EP, and overall weight gain were similar (P = 0.08 to 0.1) among treatments during the study. Egg weight was affected (P = 0.064) by DDGS treatment during phase 1. Hens fed 0, 5, 10, 15, 20, or 25% DDGS had an average egg weight of 60.6, 60.4, 60.8, 60.0, 59.0, and 59.0 g, respectively; however, no differences were detected in egg weight during phase 2. During phase 1, diets were formulated based on TSAA, allowing Met to decrease as DDGS increased, but during phase 2, diets were formulated to keep Met equal across DDGS treatments, allowing TSAA to increase as a result of high Cys in DDGS. Yolk color increased with increasing DDGS level; the highest Roche score (P = 0.001) was 7.2 for hens fed 25% DDGS. Nitrogen and P retention was greater (P = 0.003) in hens fed 25% DDGS. Also, N and P excretion decreased (P = 0.007) linearly as DDGS increased. In summary, feeding DDGS up to 25% during EP cycles had no negative effects on feed intake, EP, Haugh units, or specific gravity, and improved yolk color at the highest levels. Increasing DDGS level beyond 15% caused a reduction in egg weight during phase 1 of egg production, though no differences were observed in egg weight during phase 2. Nitrogen and P excretion were lower at higher inclusion rate of DDGS. Hens fed 25% DDGS had the highest N and P retention.

Impairment of D-alanine biosynthesis in Mycobacterium smegmatis determines decreased intracellular survival in human macrophages

d-Alanine is a structural component of mycobacterial peptidoglycan. The primary route of d-alanine biosynthesis in eubacteria is the enantiomeric conversion from l-alanine, a reaction catalysed by d-alanine racemase (Alr). Mycobacterium smegmatis alr insertion mutants are not dependent on d-alanine for growth and display a metabolic pattern consistent with an alternative pathway for d-alanine biosynthesis. In this study, we demonstrate that the M. smegmatis alr insertion mutant TAM23 can synthesize d-alanine at lower levels than the parental strain. The insertional inactivation of the alr gene also decreases the intracellular survival of mutant strains within primary human monocyte-derived macrophages. By complementation studies, we confirmed that the impairment of alr gene function is responsible for this reduced survival. Inhibition of superoxide anion and nitric oxide formation in macrophages suppresses the differential survival. In contrast, for bacteria grown in broth, both strains had approximately the same susceptibility to hydrogen peroxide, acidified sodium nitrite, low pH and polymyxin B. In contrast, TAM23 exhibited increased resistance to lysozyme. d-Alanine supplementation considerably increased TAM23 viability in nutritionally deficient media and within macrophages. These results suggest that nutrient deprivation in phagocytic cells combined with killing mediated by reactive intermediates underlies the decreased survival of alr mutants. This knowledge may be valuable in the construction of mycobacterial auxotrophic vaccine candidates.

Short-term effects of lower oil dried distillers grains with solubles in laying hen rations

Extraction of oil from dried distillers grains has become a common practice among US ethanol producers. The valuable oil has been diverted to markets other than poultry feed, leaving new dried distillers grains with solubles (DDGS) products higher in fiber and purportedly lower in ME. This study compared 3 DDGS products with 10.3, 7.3, or 5.2% ether extract, respectively, with a corn-soy control ration in young Bovan laying hens for a feeding period from 20 to 33 wk of age. The DDGS was fed at the rate of 20% of the ration. Lower oil content of DDGS had no effect on short-term egg production parameters: feed intake, egg production, egg weight or mass, and hen weight gain. The diets containing lower fat DDGS (5.2%) did have reduced AME and kilocalories per day intake for laying hens. For each percent reduction in oil from a normal DDGS sample (10.3%) to medium oil (7.3%) DDGS, AME decreased 42.3 kcal/kg of diet. However, total kilocalories per day intake did sustain good egg production during this short trial.

Limestone particle size fed to pullets influences subsequent bone integrity of hens

&NA; This study was conducted to evaluate limestone particle size (LPS) in 2 strains of laying hens housed in conventional cages or aviaries on bone integrity. Lohmann Brown and Bovan White pullet chicks were started in equal numbers on the floor or in battery brooders and were intermingled throughout all subsequent housing systems. At 5 wk of age, 432 floor‐raised pullets were moved to 8 aviary cages. At 10 wk, 256 battery‐raised pullets were transferred to 64 conventional layer cages. Pullets were given diets containing fine (LPS‐FINE, 0.431 mm) or a blend of fine and coarse (LPS‐BLEND, 0.879 mm) LPS from 7 to 17 weeks. Data were analyzed as a split plot factorial design with strain as subplot and with 4 replicates for each treatment combination. Body weight, feed intake, egg production, and eggshell breaking strength and percentage were measured. Tibia bone mineral density (BMD) was determined using a dual energy x‐ray absorptiometry. Presence of keel indentations, curvatures, or fractures was recorded. LPS‐BLEND increased BMD (0.215 vs. 0.208, P = 0.03) at 18 weeks. During the pullet phase, the odds of pullets fed LPS‐FINE displaying keel curvatures were 2.8 times the odds of those fed LPS‐BLEND (P = 0.04). At 54 wk, hens fed LPS‐BLEND as pullets had lower odds of keel indentations (P = 0.02). Brown aviary hens fed LPS‐BLEND as pullets had the lowest egg production compared to the rest of the treatment combinations (P = 0.004). Taken together, feeding LPS‐BLEND to pullets improved bone mineralization at the onset of sexual maturity and reduced keel damage during the pullet and layer phases, regardless of strain; however, LPS‐BLEND was associated with lower egg production in Brown hens housed in aviaries compared to all others.