Performance by spring and fall-calving cows grazing with full, limited, or no access to toxic Neotyphodium coenophialum-infected tall fescue1

Abstract

Replacing toxic, wild-type Neotyphodium coenophialum-infected tall fescue (E+) with nontoxic, N. coenophialum-infected tall fescue (NE+) has improved cow performance, but producer acceptance of NE+ has been slow. The objective was to compare performance by spring- and fall-calving cows grazing either E+ or NE+ at different percentages of the total pasture area. Gelbvieh×Angus crossbred cows (n=178) were stratified by BW and age within calving season and allocated randomly to 1 of 14 groups representing 5 treatments for a 3-yr study: i) Fall-calving on 100% E+ (F100); ii) Spring-calving on 100% E+ (S100); iii) Fall-calving on 75% E+ and 25% NE+ (F75); iv) Spring-calving on 75% E+ and 25% NE+ (S75); and v) Spring-calving on 100% NE+ (SNE100). Groups allocated to F75 and S75 grazed E+ until approximately 28 d before breeding and weaning, then were then moved to their respective NE+ pasture area for 4 to 6 wk; those allocated to F100, S100, and SNE100 grazed their pastures throughout the entire year. Samples of tall fescue were gathered from specific cells within each pasture at the time cows were moved into that particular cell (∼1 sample/mo). Blood samples were collected from the cows at the start and end of the breeding season. Stocking rate for each treatment was 1 cow/ha. Forage IVDMD, CP, and total ergot alkaloid concentrations were affected (P<0.05) by the treatment×sampling date interaction. Hay offered, cow BW, and BCS at breeding, end of breeding, and at weaning were greater (P<0.05) from fall-calving vs. spring-calving. Cow BW at weaning was greater (P<0.05) from F75 and S75 vs. F100 and S100. The calving season×NE+ % interaction affected (P<0.05) calving rates. Preweaning calf BW gain, actual and adjusted weaning BW, ADG, sale price, and calf value at weaning were greater (P<0.05) from fall-calving vs. spring-calving and from SNE100 vs. S75 except for sale price which was greater (P<0.05) from S75 vs. SNE100. Cow concentrations of serum prolactin at breeding and serum NEFA at the end of breeding were affected (P<0.05) by the calving season×NE+ % interaction. Serum Zn and Cu concentrations from cows were affected (P<0.05) by calving season. A fall-calving season may be more desirable for cows grazing E+, resulting in greater calving rates, cow performance, and calf BW at weaning, whereas limited access to NE+ may increase calving rates, serum prolactin, and NEFA concentrations during certain times in the production cycle, particularly in spring-calving cows.

Evaluation of eastern gamagrass and a sorghum × sudangrass for summer pasture

“…Another challenge within the TF Belt, particularly for reproductive animals such as first‐calf heifers, is fescue toxicosis caused by a symbiotic fungal endophyte ( Neotyphodium coenophialum ) which produces ergot alkaloids. It has been estimated that greater than 90% of TF pastures are infected with this endophyte (Kallenbach, 2015) leading to reductions in reproductive performance (Caldwell et al., 2013; Campbell, Backus, Dixon, Carlisle, & Waller, 2013; Porter & Thompson, 1992). In addition, heifers may be particularly sensitive to fescue toxicosis (Burns, 2012; Drewnoski, Oliphant, Poore, Green, & Hockett, 2009; Paterson, Forcherio, Larson, Samford, & Kerley, 1995) making non‐toxic summer forage especially important for heifer development (Keyser et al., 2016).…”

Risk and Returns of Spring and Fall Calving for Beef Cattle in Tennessee

“…Research has shown that a controlled calving season (e.g., in the spring or fall) is more profitable for beef cattle producers than year-round calving (Doye, Popp, and West, 2008). However, selecting an optimal calving season depends on a complex set of factors including nutritional demands of brood cows, forage availability, calf weaning weights, calving rates (calves weaned per cow exposed to a bull), seasonality in cattle and feed prices, and labor availability (Bagley et al, 1987; Caldwell et al, 2013; Campbell et al, 2013; Leesburg, Tess, and Griffith, 2007; Smith et al, 2012). Most cow-calf producers using a defined calving season in the southeastern United States follow a spring-calving season, beginning in January and ending around mid-March (Campbell et al, 2013).…”

Ergot Alkaloid Effects on Bovine Sperm Motility &lt;i&gt;In Vitro&lt;/i&gt;

“…More specifically, ET and DHET reduced the percentage of spermatozoa that were motile, progressive, and rapid, which are characteristics associated with sperm viability. These data provide a possible explanation for decreased conception rates and reproductive performance for cattle grazing E+ [13]. Chemical structure of the alkaloids used in our study likely explains their effects on sperm motility.…”