The objective of this study was to compare ram semen quality characteristics from a first to a second semen collection on the same day. Six 5-mo old Hampshire rams at the SDSU sheep unit had a semen evaluation performed at six week intervals between October and April. Semen was collected by electro-ejaculation and evaluated both by a veterinarian trained in visual semen quality scoring and with a computer assisted sperm analysis system (CASA). Data were analyzed using the MIXED and CORR procedures of SAS. There were significant positive correlations (P < 0.01) in the visual score for both motility and morphology scores between the first and second collections. When semen was analyzed by CASA there was a positive correlation (P < 0.01) between the first and second collection for distal droplets, percent normal, percent motile, percent progressive, curvilinear velocity, and straight line velocity. Although, there was no significant difference in the actual visual score between the first and second ejaculate for morphology (P = 0.85) or motility (P = 0.49). Furthermore, when evaluated with the CASA there was no significant difference in the value between the first and second ejaculate for morphology (P = 0.99), motility (P = 0.12), or proximal droplets (P = 0.74). However, the percentage of progressively motile sperm tended to increase from the first to the second ejaculate (P = 0.07; 23% to 33%). Curvilinear velocity also tended to increase from the first to the second ejaculate (P = 0.06; 132 ± 11.9 um/sec to 164 ± 11.9 um/sec), and straight line velocity did increase (P = 0.05) from the first collection to the second (73.8 ± 8.1 um/sec to 96.6 ± 8.1 um/sec). In conclusion, a comparison of duplicate semen samples, sperm morphology and motility measurements were similar using subjective or objective analytics. However improvements were detected in percentage of progressive sperm and velocity of sperm (both curvilinear and straight line) with a second sampling. Although the objective analytics at least tend to show sampling differences for several sperm motion traits the results from this study support industry practices for a single semen sample to subjectively assess semen quality characteristics in a ram.

We conducted 2 experiments to determine lysine loss from 2 lipid-coated lysine products after mixing with silage. In our first experiment, we mixed 2 lipid-coated lysine products, crystalline lysine or crystalline lysine and amounts of lipid identical to amounts included in lipid-coated lysine products, with alfalfa or corn silage that had 2 different amounts of acidity. Lysine appeared to disassociate from lipid-coated lysine products in a nonlinear manner after mixing with either alfalfa or corn silage at different amounts of acidity. Additionally, silage source and acidity affected amounts of lysine released from lipid-coated lysine products after mixing. In a corresponding experiment, in vitro estimates of lysine available to ruminal microbiota after mixing with alfalfa or corn silage at different amounts of acidity were measured by ammonia release. In vitro measures were conducted with or without monensin to allow estimates of effects of monensin on amounts of lysine released from the 2 lipid-coated lysine products. It is unclear whether in vitro estimates of lysine fermentation from lipid-coated lysine are truly reflective of ruminal degradation of lysine from lipid-coated lysine because amounts of time needed to measure differences between different lysine sources were greater than typical estimates of mean ruminal particulate retention time. Nonetheless, monensin apparently reduced ammonia release from lysine, but ammonia release from lipid-coated lysine did not differ from crystalline lysine. Clearly, methods of manufacture together with physical and chemical characteristics of diet can affect amounts of lysine provided from lipid-coated lysine products to ruminants.

Estimates of diet quality from samples of mechanically harvested corn residues likely under-predict nutrient density in diets selected by grazing cattle. Our objective was to determine if measures of chemical composition or near-infrared reflectance spectroscopy (NIRS) of diet samples collected from ruminally cannulated cows could allow accurate estimates of diet selection among cows fed binary mixtures of cornstalk and noncornstalk (i.e., husk and leaf) residues. Six ruminally cannulated cows were placed in a 6 × 6 Latin square to evaluate predictions of diet intake. After complete ruminal evacuation, cows were fed 1-kg meals (DM-basis) containing different combinations of cornstalk and noncornstalk residues in ratios of 0:100, 20:80, 40:60, 60:40, 80:20, 100:0. Diet samples from each meal were collected by removal of ruminal contents after 1-h and were either machine-rinsed, hand-rinsed or unrinsed to evaluate effects of endogenous compounds on predictions of diet composition. Diet samples were analyzed for NDF, ADF, acid detergent insoluble ash (ADIA), ADL, CP and NIRS to calculate diet composition. Greater amounts of rinsing increased NDF and ADF content and decreased ADIA and CP content of diet samples (P < 0.01). Rinsing tended to increase (P < 0.06) ADL content of diet samples. Differences in concentration between cornstalk and noncornstalk residues within each chemical component were standardized by calculating a coefficient of variation (CV). Accuracy and precision of estimates of diet composition were analyzed by regressing predicted diet composition and known diet composition. Predictions of diet composition were improved by increasing differences in concentration of chemical components between cornstalk and noncornstalk residues up to a CV of 22.6 ± 5.4%. Predictions of diet composition from unrinsed ADIA and machine-rinsed NIRS had the greatest accuracy (slope = 0.98 and 0.95, respectively) and large coefficients of determination (r2 = 0.86 and 0.74 respectively). Subsequently, a field trial was performed to evaluate predictions of diet composition in cattle grazing corn residue. Five cows were placed in 1 of 10 paddocks (6.1 AUM/ha) and allowed to continuously graze or to strip-graze (4.7% of BW/12 h) corn residues. Predictions of diet composition from ADIA, ADL and NIRS did not differ (P = 0.99), and estimates of cornstalk intake tended to be greater (P = 0.09) in strip-grazed compared to continuously grazed cows. These data suggest that diet composition can be predicted by chemical components or NIRS by ruminal collection of diet samples among cattle grazing binary mixtures of forage.

The objective of this study was to evaluate changes in semen quality for up to 6 months after puberty in young rams. Six 5 mo-old Hampshire rams at the SDSU sheep unit had a breeding soundness examination (BSE) performed every six weeks from October to April (5 collections). Semen was collected by electro-ejaculation and evaluated subjectively by a trained veterinarian and with a computer assisted sperm analysis system (CASA). At the initial BSE exam four of the six rams had already reached puberty (> 50% motile and > 70% normal), one additional ram reached puberty by the second collection period, and the last ram reached puberty by the fourth collection period. Data were analyzed with the first or pubertal collection as time 1 using the MIXED procedure of SAS. By visual evaluation there was no effect of collection period on sperm morphology (P = 0.41); however, motility score did increase (P = 0.05) as interval post puberty increased. Based on CASA analysis, there was no effect of collection period on morphology (P = 0.13), percent motile (P = 0.51), percent progressive (P = 0.25), curvilinear velocity (P = 0.74), or straight line velocity (P = 0.53). Based on BSE scores three rams were selected (highest, lowest and intermediate) for exposure to 10 synchronized ewes per ram. Conception rates of ewes mated were 60%, 100% and 25%, respectively; however these conception rates were not correlated with visual motility or morphology scores at the first (P = 0.36 and 0.53) or last BSE (P = 0.98 and 0.47). Nor were they correlated with CASA morphology (P = 0.57 and 0.63), percent motile (P = 0.64 and 0.90), percent progressive (P = 0.68 and 0.89), curvilinear velocity (P = 0.99 and 0.84), or straight line velocity (P = 0.81 and 0.99). In conclusion, motility score improved as post puberty interval increased, but morphology score was unchanged. CASA data supports the observed lack of change in morphology scores over time when related to puberty status. In addition, there was no correlation between subjective scores or objective measures and synchronized conception rates. Finally, a ram BSE evaluation is an important fertility index however is not predictive of overall fertility.

Abstract We conducted 2 experiments to determine lysine bioavailability from 2 lipid-coated lysine products. In an in vitro experiment we mixed each lipid-coated lysine product with either alfalfa- or corn-silage at different amounts of acidity. Scanning electron micrographs indicated that surface structure of each lipid-coated lysine particle was eroded after mixing with silage. Additionally, visual evaluation of scanning electron micrographs suggested that peripheral surface abrasion of lipid-coated lysine may be greater when lipid-coated lysine was mixed with alfalfa silage in comparison to corn silage. In a corresponding experiment, in vivo measures of lysine bioavailability to sheep from 2 lipid-coated lysine products and lysine-HCl were determined after mixing in corn silage. Plasma lysine concentrations increased linearly (P < 0.01) in response to abomasal lysine infusion indicating that our model was sensitive to increases in metabolizable lysine flow. Bioavailability of each lipid-coated lysine source and dietary lysine-HCl were calculated to be 23, 15, and 18%, respectively. Even though each dietary source of lysine increased plasma lysine, rates of increases in plasma lysine from one lipid-coated lysine source (linear; P = 0.20) and lysine-HCl (linear; P = 0.11) were not different from plasma lysine levels supported by diet alone. However, the rate of plasma lysine increase in response to lysine from the other lipid-coated lysine source was greater (P = 0.04) than plasma lysine from feed alone. Nonetheless, the rate of plasma lysine increase in response to lipid-coated lysine did not differ (P ≥ 0.70) from the rate of plasma lysine increase from lysine-HCl. Clearly, methods of manufacture, together with physical and chemical characteristics of diet, can impact amounts of metabolizable lysine provided from lipid-coated lysine products. Direct measures of lysine bioavailability from lipid-coated lysine products after mixing with diets should be based on measurements with the products treated similarly to the method of feeding.

OBJECTIVE:To determine the prevalence and temporal onset of lung lesions in lambs and the impact of lung lesions on growth of affected lambs. ANIMALS:259 crossbred wether lambs from a single flock in the upper Midwestern United States. PROCEDURE:An observational study was conducted. Lambs born in the spring and fall were slaughtered at finished weight or at a predetermined time point. Lungs of each lamb were examined and classified as normal, moderate lesions (consolidation > 5% but < or = 50% of any lobe), or severe lesions (consolidation > 50% of any lobe). Data were examined to detect effects of prevalence or severity of lung lesions on growth and carcass traits. RESULTS:57 of 89 (64%) spring-born lambs had lung lesions characterized by consolidation of lung tissue. A small number of lambs had pulmonary adhesions or active abscesses. In contrast, only 31 of 108 (29%) fall-born lambs had lung lesions. Severe lung lesions were associated with a significant reduction in average daily gain. Severe lung lesions were not detected until the middle of the finishing period and were associated with culture of Mannheimia haemolytica or Pasteurella multocida. CONCLUSIONS AND CLINICAL RELEVANCE:Analysis of results indicates that the prevalence of severe lung lesions can be quite high in lambs. Severe lung lesions can lead to greatly decreased growth performance of lambs.