Tissue mineral concentrations and osteochondrosis lesions in prolific sows across parities 0 through 7.

Mortality in swine herds is often associated with lameness, and trace minerals are implicated in maintaining integrity of skeletal tissues. The objectives of this study were to determine if prolific sows displayed evidence of trace mineral depletion with age and to determine the prevalence of osteochondrosis (OC) lesions. Reduced mineral concentrations with age would support recommendations for an increase in the amount of dietary minerals. Tissue samples were collected from 66 sows selected to represent a cross-sectional profile of a prolific herd fed diets with inorganic sources of trace minerals fortified at concentrations typically found in commercial diets. Females ranged from nulliparous (parity 0) to parity 7 with a lifetime average of 12.9 ± 0.5 pigs born alive per litter. Minerals were assessed in humerus, scapula, ovary, liver, and muscle (psoas major) tissues. Percent bone ash increased (P < 0.05) with parity from 64 to 66% but differed among bone sections. The Ca (39.0%) and P (18.9%) concentrations in bone ash were essentially constant in all sections and parities. Bone Cu, Fe, Mn, and Zn concentrations varied among sections, but differences due to parity (P < 0.05) were only detected in Fe. Bone Fe decreased from approximately 49 µg/g ash in parity 0 and 1 sows to approximately 29 µg/g ash in parity 7, likely reflecting loss of hemopoietic tissue with age. No evidence was detected in liver for depletion of trace minerals across parity; however, liver Cu and Zn concentrations tended to increase with age. Liver Mn concentrations varied with parity, but no consistent trend with parity was evident. Ovary Cu and Mn concentrations varied dramatically as a function of the reproductive status, but no evidence was detected for depletion with parity. Articular surfaces of the distal scapula and proximal and distal humerus were evaluated grossly for prevalence of OC; bones were then sectioned to evaluate lesions in subchondral bone and physis. Incidence of OC lesions on the articular-epiphyseal cartilage complex varied among bone sites, but differences across parities were not detected. In a subset of sows with subchondral bone lesions, the lesions appeared severe enough to contribute to clinical lameness, particularly in the distal humerus site. However, none of the sows exhibited lameness at slaughter. As no reductions in mineral concentrations with age were detected, recommendations to increase dietary mineral supplementation with age were not supported.

Semen production and fertility issues related to differences in genetic lines of boars.

Boars have been reported to differ in various characteristics important to productivity of AI units. These aspects include sensitivity to seasonal infertility, ejaculate volume x age interactions, optimum collection frequency, discard (trash) rate of ejaculates, age of puberty, libido and trainability, and semen shelf life. In addition to differences among individual boars, there were also identifiable differences among breeds, between purebreds and crossbreds, and between lines. The percentage of ejaculates discarded varied among seasons and among breeds within season, with maternal purebred lines being the most sensitive to warmer temperatures. These same lines were also slower to mature and produced fewer sperm per ejaculate. Breeds differed in the sustainability of motility in stored extended semen, and in farrowing rates. Boar centers need to factor breed differences into their decision-making processes to ensure adequate boar power and customer satisfaction.

Comparison of four methods for forage nitrate analysis.

Twenty forage samples were collected and selected for variation in nitrate content. Each forage samples was analyzed 4 times by 4 different methods: diphenylamine spot plate, spectrophotometric, nitrate-selective electrode, and high-performance liquid chromatographic. Five feed extracts were spiked with 2 different amounts of nitrate and analyzed by each method. The spectrophotometric and nitrate-selective electrode had similar percent recoveries, which were close to 100%. The nitrate-selective electrode method had the least variation of the 4 methods. The diphenylamine spot plate method had the poorest average recovery, greatest variation, and was the least accurate. The average coefficients of variation for all samples within a method were 15%, 12%, 6.4%, and 16 for the diphenylamine spot plate, spectrophotometric, nitrate-selective electrode, and high-performance liquid chromatographic methods, respectively. The variation in the nitrate-selective electrode method was lower (P < 0.05) than the other methods. The results from this study suggest that the nitrate-selective electrode method is more accurate and precise than the other methods of analysis tested.

Effect of dietary protein and exogenous gonadotropin-releasing hormone on circulating progesterone concentrations and performance of Holstein cows.

Sixty-three Holstein cows were used in a 2 x 2 factorial arrangement of treatments to determine the effects of dietary protein and exogenous gonadotropin-releasing hormone on performance postpartum and on circulating concentrations of progesterone. The experimental diets, 14 or 20% CP (dry basis), were fed from parturition to 14 wk postpartum. Blood serum urea N was elevated in the cows fed the 20% versus 14% CP diet. Feed intake was increased, but yield and composition of milk were not affected by the higher protein diet. Circulating concentrations of progesterone were lower in cows fed 20% than 14% protein on d 12 of both the synchronized and subsequent estrous cycles. Exogenous gonadotropin-releasing hormone administered on d 12 of the preceding estrous cycle did not increase the concentration of progesterone on d 12 of the subsequent estrous cycle. Luteal phase concentrations of progesterone were reduced by high dietary protein, but were not affected by gonadotropin-releasing hormone given on d 12 of the preceding cycle.