Author: Rodrigo Da Silva MarquesPublisher:
ISBN:
Category : Beef cattle
Languages : en
Pages : 99
Book Description
Two experiments evaluated nutritional management of late-gestating beef cows to enhance offspring productivity. The objective of experiment 1 was to evaluate the effects of organic and inorganic Cu, Mn, Zn, and Co supplementation to beef cows during late-gestation on performance and physiological responses of the offspring. The objective of experiment 2 was to evaluate the effects of rumen-protected essential fatty acid (EFA) supplementation to beef cows during the last trimester of gestation on performance and physiological responses of the offspring. In experiment 1, 84 multiparous, non-lactating, pregnant Angus × Hereford cows were ranked by pregnancy type (AI = 56 and natural service = 28), BW, and BCS, and allocated to 21 drylot pens at the end of their 2nd trimester of gestation (day 0). Pens were assigned to receive forage-based diets containing: 1) sulfate sources of Cu, Co, Mn, and Zn (INR), 2) an organic complexed source of Cu, Mn, Co, and Zn (AAC; Availa®4; Zinpro Corporation, Eden Prairie, MN), or 3) no supplemental Cu, Co, Mn, and Zn (CON). Diets were offered from day (d) 0 until calving and formulated to meet requirements for energy, protein, macrominerals, Se, I, and vitamins. The INR and AAC diets provided the same daily amount of Cu, Co, Mn, and Zn. Cow BW and BCS were recorded, and liver samples were collected on d -10 and 2 weeks (wk; d 75) before the calving season. Within 3 h after calving, calf BW was recorded, liver samples were collected, and the expelled placenta was retrieved (n = 47 placentas). Calves were weaned on d 283 of the experiment, preconditioned for 45 d (d 283 to 328), transferred to a growing lot on d 328, and moved to a finishing lot on d 440 where they remained until slaughter. Liver Co, Cu, and Zn concentrations on d 75 were greater (P ≤ 0.05) for INR and AAC compared with CON cows, whereas INR had reduced (P = 0.04) liver Co but greater (P = 0.03) liver Cu compared with AAC cows. In placental cotyledons, Co concentrations were greater (P ≤ 0.05) in AAC and INR compared with CON cows, whereas Cu concentrations were only increased (P = 0.05) in AAC compared with CON cows. Calves from INR and AAC had greater (P
