Forage quality, animal performance and behaviour of bred beef heifers grazing stockpiled perennial and annual forages in the late fall/early winter in Manitoba

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Dickson, Jordan
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Stockpile grazing is practiced to extend the grazing season of beef cows in western Canada. Little research has been conducted to identify plant species for successful stockpile grazing of bred beef heifers during the late fall/early winter. Objectives of this study were to compare the three stockpiled perennial and one annual forage stand based on: 1) forage quality, yield and plant height, 2) performance (weight gain, serum urea nitrogen, intake and methane output) of bred beef heifers, 3) animal activity (distance traveled and time spent at shelter/water). Four stockpiled forage treatments were grazed for two, 28-d periods near Brandon, Manitoba, Canada. Treatments included: 1) Courtney tall fescue (T)/Fleet meadow bromegrass (M)/Yellowhead alfalfa (A; TAM), 2) Killarney orchardgrass (OG)/Algonquin alfalfa (A; OGA), 3) Courtney tall fescue/Algonquin alfalfa/Oxley II cicer milkvetch (C; TAC) and 4) Fusion corn (COR) in a randomized complete block design (RCBD) with 4 heifers/replicate/treatment. Forage biomass yield in performance pastures of COR (6,342 kg DM ha-1) was 68%, 79% and 57% higher (P=0.011) than OGA, TAC, and TAM, respectively, which did not differ from each other. Crude protein was highest in TAC (10.29% and 10.90%) and COR was the lowest (6.87% and 6.76%). However, COR had the highest in TDN (72.14% and 71.90%) when compared to perennial forage treatments. All heifers gained weight in Period 1 (1.36 kg d-1) suggesting that all treatments could be successfully stockpile grazed in the late fall. When temperature fell to <-18°C Period 2 (-2 kg d-1), all heifers lost weight and those grazing perennial pastures spent more time (30-54% of the day) near windbreak shelters. Heifers grazing COR spent 7% of the day near shelter, suggesting COR provided adequate shelter. TAC was identified as the superior perennial forage treatment for stockpile grazing, based on higher CP and lower NDF compared to OGA and TAM, as well as improved ADG compared to OGA and numerically higher ADG compared to TAM, Although COR had increased yield and TDN with lower CP compared to TAC, ADG was comparable between the two treatments. Nonetheless, significant weight loss in Period 2 indicated that all treatments required supplementation.
Stockpile grazing, Extended grazing, Beef heifers, Stockpile forage, forage, Animal behaviour, Winter grazing, Fall grazing