Bull selection and management in extensive rangeland production systems of California: a producer survey.

California's approximately 660,000 head of beef cattle are highly dependent on range bulls used to produce offspring that can perform across the state's diverse ecological regions. Bulls need to be functional on rugged coastal landscapes, rolling foothills, deserts, and in high-elevation terrain. Few data exist that indicate factors related to selection, maintenance, and longevity of bulls used in rangeland landscapes. Objectives herein, were to assess factors influencing bull purchasing, management, and culling decisions of California beef producers. Surveys were mailed to the California Cattlemen's Association membership (N = 1,410) with ~ 16% response rate (N = 227). Mean age and years of bull selection experience of respondents was 61 ± 1 yr and 27 ± 1 yr, respectively. Respondents managed cattle on a total of 694,949 hectare of owned, private leased, and leased public rangelands in California and surrounding states. Cow-calf herd size was 333 ± 92 head and bull battery averaged 18 ± 2 head with average bull longevity of 5 ± 1.3 yr. The average price paid for bulls in the last 2 yr was $5007 ± 163.33, while the highest price paid in the last 5 yr was $7291 ± 335.40. Survey responses were used to define current factors driving management after purchase and for subsequent breeding seasons. After bull purchase, 48% of producers turned bulls out directly with females, while 52% held bulls until the following breeding season. Additionally, most producers (70%) did not manage bulls to reduce condition after purchase. Semen quality analysis, a major component of a breeding soundness exam, was evaluated annually by 45% of respondents, while 20% of respondents never evaluated semen quality. Respondents indicated bull age (35%) and structural soundness (29%) as the most common factors for culling bulls. This research shows that despite the variability in operation demographics, there were similarities in beef bull selection and management across the state. Additionally, these data suggest the need for additional research focused on bull selection and management to maximize producer investment in reproduction.

Effects of red clover isoflavones on tall fescue seed fermentation and microbial populations in vitro.

Negative impacts of endophyte-infected Lolium arundinaceum (Darbyshire) (tall fescue) are responsible for over $2 billion in losses to livestock producers annually. While the influence of endophyte-infected tall fescue has been studied for decades, mitigation methods have not been clearly elucidated. Isoflavones found in Trifolium pratense (red clover) have been the subject of recent research regarding tall fescue toxicosis mitigation. Therefore, the aim of this study was to determine the effect of ergovaline and red clover isoflavones on rumen microbial populations, fiber degradation, and volatile fatty acids (VFA) in an in vitro system. Using a dose of 1.10 mg × L-1, endophyte-infected or endophyte-free tall fescue seed was added to ANKOM fiber bags with or without 2.19 mg of isoflavones in the form of a control, powder, or pulverized tablet, resulting in a 2 × 3 factorial arrangements of treatments. Measurements of pH, VFA, bacterial taxa, as well as the disappearance of neutral detergent fiber (aNDF), acid detergent fiber (ADF), and crude protein (CP) were taken after 48 h of incubation. aNDF disappearance values were significantly altered by seed type (P = 0.003) and isoflavone treatment (P = 0.005), and ADF disappearance values were significantly different in a seed × isoflavone treatment interaction (P ≤ 0.05). A seed × isoflavone treatment interaction was also observed with respect to CP disappearance (P ≤ 0.05). Eighteen bacterial taxa were significantly altered by seed × isoflavone treatment interaction groups (P ≤ 0.05), eight bacterial taxa were increased by isoflavones (P ≤ 0.05), and ten bacterial taxa were altered by seed type (P ≤ 0.05). Due to the beneficial effect of isoflavones on tall fescue seed fiber degradation, these compounds may be viable options for mitigating fescue toxicosis. Further research should be conducted to determine physiological implications as well as microbiological changes in vivo.

Winter grazing of stockpiled native forages during heifer development delays body weight gain without influencing final pregnancy rates.

The objective of this study was to test the effects of protein supplementation strategy and different stockpiled forage species on growth, nutritional status, and reproductive performance of yearling beef heifers. In a 5-yr study, yearling beef heifers (n = 266) were stratified by body weight (BW) at weaning to 1 of 3 stockpiled forages: 1) endophyte-infected tall fescue (TF, Schedonorus arundinaceus (Schreb.) Dumort; 7.21% crude protein [CP] and 67.13% neutral detergent fiber [NDF], dry matter [DM] basis), 2) big bluestem (Andropogon gerardi Vitman) and indiangrass (Sorghastrum nutans L.) combination (BI; 4.32% CP and 71.06% NDF, DM basis), or 3) switchgrass (SG,Panicum virgatum L.; 3.87% CP and 76.79% NDF, DM basis). Forage treatments were then randomly assigned to receive 1 of 2 supplement types: 1) 0.68 kg heifer-1 d-1 of dried distillers grains with solubles (DDGS: 28% CP and 108% total digestible nutrients [TDN]) or 2) 0.22 kg heifer-1 d-1 of blood meal and fish meal (BF: 72.5% CP and 77.5% TDN), resulting in a 3 × 2 factorial arrangement of treatments. Each year, twenty-one 1.2-ha pastures (7 pastures per forage type) were utilized with 2 to 3 heifers per pastures. Treatments were initiated in January and terminated in April at the initiation of breeding. Initial BW was not different (P ≥ 0.22) by forage or supplement type. During the rest of the grazing period, BW was greater (P < 0.01) for TF heifers. However, average daily gain (ADG) was greater (P < 0.01) for BI and SG heifers from breeding to final pregnancy diagnosis. Heifers grazing TF pastures had greater (P < 0.01) overall ADG than their counterparts. The percentage of mature BW (MBW) at breeding was greater (P < 0.01) for TF heifers. Heifer BW and ADG was not influenced (P ≥ 0.06) by supplementation strategy. Serum glucose concentrations were not different (P ≥ 0.44) among forage type or supplement strategy. Pregnancy rates at fixed timed-artificial insemination and overall pregnancy rates did not differ (P ≥ 0.38) by forage or supplement treatment. Owing to forage nutritive value differences, heifers grazing low-quality, warm season grasses lost BW prior to the initiation of the breeding season. However, a negative BW gain prior to breeding did not negatively impact overall pregnancy rates.