Fall Grazing Of Annual Forages With Fall Born Lambs May Improve Animal Growth And Total Protein Concentrations When Compared To Stockpiled Pastures

Abstract There is a consistent demand for grass-fed livestock products in the domestic market. Alternative grazing strategies should be considered to sustain the year-round production of grass-fed products that meet consumer demand and support animal health and performance. The objective of this study was to evaluate the effect of annual forages on the growth and parasite resilience of growing lambs. We hypothesized that lambs grazing annual forages would increase their body weight at a greater rate when compared to lambs grazing stockpiled pasture. A total of 54, 60-day-old lambs (24 kg ± 4.9 kg) were stratified by weight, sex, and randomly assigned to one of three grazing treatments: 1) oats (O); 2) turnips (T); and 3) stockpiled tall fescue pasture (F). Lamb body weight and indices of parasitism were measured every 14 days. Data were analyzed using PROC MIXED in SAS. There was a treatment × day effect for body weight such that T lambs were heavier on days 42 and 56 than O and F lambs (P < 0.03). Furthermore, there was a treatment × day effect for average daily gain (ADG) whereas T lambs had a greater ADG on days 28 and 42 than O and F lambs (P < 0.0001). In addition, on day 42, F lambs had a greater ADG when compared to O lambs (P < 0.003). For the indices of parasitism, T lambs demonstrated lesser total plasma protein concentration on days 28 and 42 when compared with O lambs (P < 0.05). Forage type plays a critical role in lamb resilience to gastrointestinal parasites and body weight gain whereas T lambs showed a greater liveweight gain. However, T lambs also demonstrated lesser concentrations of total plasma protein when compared to O lambs. Under these conditions, annual forages adequately sustained the growth of fall grazing lambs.