Publications by authors named "John Andrae"

Supplementation of beef cattle can be used to meet both nutrient requirements and production goals; however, supplementation costs influence farm profitability. Common supplementation delivery strategies are generally designed to provide nutrients to the mean of the group instead of an individual. Precision individual supplementation technologies, such as the Super SmartFeed (SSF, C-Lock Inc.

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The objective of this study was to evaluate the yield, nutritional composition, and digestibility of conventional (CON) and brown midrib (BMR) pearl millet (PM) with different establishment dates, maturity at harvest and when mixed with cowpea (CWP). In trial 1, CON and BMR were planted on two different dates. In trial 2, CON and BMR, mixed or not with CWP, were harvested when PM was at the boot or heading stages.

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Grazing endophyte-infected, toxic tall fescue reduces cow/calf production; therefore, this study examines alternate strategies such as use of novel endophyte fescue varieties during late gestation and early lactation or genetic selection of resistant cows. Pregnant cows (n = 75) were randomly assigned to fescue endophyte type: 1) endophyte-infected ergot alkaloid producing tall fescue (E+) or 2) novel endophyte-infected, non-toxic tall fescue (NOV) within maternal (A|A, n = 38 and G|G, n = 37) genotype to examine changes in cow/calf performance and milk production during late gestation and early lactation. Grazing E+ fescue pastures during late gestation reduced cow body weight gain but did not alter calf birth weight compared to NOV.

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Endophyte-infected tall fescue (E+) produces ergovaline and ergovalinine, which are mycotoxins that act as dopamine agonists to suppress prolactin and induce vasoconstriction. The experiment was designed as a 3 × 2 × 2 factorial with genotype (AA, AG, GG), fescue seed (endophyte-free, E- or endophyte-infected, E+), stage of gestation (MID, d (day) 35-85; LATE, d 86-parturition) and all interactions in the model. Pregnant Suffolk ewes (n = 60) were stratified by genotype and fed E+ or E- seed in a total mixed ration according to treatment assignment.

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Weaned lambs (n = 82), born to ewes fed endophyte-free (E-) or endophyte-infected (E+; 1.77 mg hd d ergovaline + ergovalinine) tall fescue seed from d 35 to 85 of gestation (MID) and/or d 86 of gestation to parturition (LATE), were used to examine how ergot alkaloid exposure during fetal development altered subsequent puberty attainment or carcass quality. Lambs were weaned at 75 d of age and separated by sex to assess puberty in ewe lambs ( = 39) and to evaluate growth, carcass and meat quality in wethers ( = 43).

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Tall fescue [Lolium arundinaceum (Scheyreb.) Darbysh] is the primary cool season forage grass in the Southeastern United States. Most tall fescue contains an endophytic fungus (Epichloë coenophiala) that produces ergot alkaloids and upon ingestion induces fescue toxicosis.

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Previous research has shown that livestock exposed to ergot alkaloids results in decreased vasoactivity of gastrointestinal and peripheral vasculature. Little is known regarding the effect ergot alkaloid exposure during gestation may have on vasculature supporting the fetus. The objective of this study was to evaluate contractile responses of uterine and umbilical arteries collected from ewes consuming ergot alkaloids during gestation.

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Tall fescue [Schedonorus phoenix (Scop.) Holub] accounts for nearly 16 million hectares of pasture in the Southeastern and Mid-Atlantic U.S.

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Tall fescue [Lolium arundinaceum (Schreb.) Darbysh; Schedonorus phoenix (Scop.) Holub] is the primary cool season perennial grass in the eastern U.

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