Effects of Feeding Graded Levels of Black Spruce Needles and Branches on
Beef Cow Performance and Health During Mid to Late Gestation
Pregnant beef cows (56; 727 ± 102 kg BW) in second trimester were used to examine black spruce (BSP) needles and branches for replacing alfalfa silage in wintering cow diets. Five dietary treatments assessed BSP inclusion rates (0, 15, 22.5, 30, 37.5% in the diet) for 92 days up until 2 weeks before start of calving using a randomized complete block design (10-12 cows/treatment). There were linear decreases (P < 0.001) in total weight gain, average daily gain (ADG) and dry matter intakes (DMI) as amounts of dietary BSP increased. Low DMI feeding BSP may be attributed to palatability issues and lower rates of digestion. Changes in body condition score (BCS) increased(P < 0.003) as dietary BSP increased. These effects are supported by corresponding linear decreases (P < 0.001) for changes in rump fat cover and increases (P < 0.001) in serum non-esterified fatty acids as dietary BSP increased. Post-feeding of test diets, there were no dietary treatment differences (P > 0.42) for calf birth and weaning weights and cow pregnancy and culling rates. Based on this study, incorporation of BSP into gestating cow diets cannot be recommended.