Effects of interval-feeding whole sunflower seeds during mid to late gestation on performance of beef cows and their progeny1,2

Abstract

This experiment was conducted to determine the effects of interval feeding of whole sunflower seeds on the performance of beef cows and their progeny. During mid to late gestation, 144 multiparous, spring-calving beef cows (588 kg of initial BW; 5.6 initial BCS; 4 to 13 yr old) were individually fed 1 of 3 supplements 4 d/wk for a 76-d period. Supplements (DM basis) included: 1) 0.68 kg of soybean meal/feeding (NCON); 2) 3.01 kg of a soybean hull-based supplement/feeding (PCON); and 3) 1.66 kg of whole sunflower seeds high in linoleic acid/feeding (WSUN). Supplements were formulated to provide similar amounts of CP and ruminally degraded intake protein; PCON and WSUN were also formulated to be isocaloric. During the supplementation period, cows had free-choice access to bermudagrass (Cynodon dactylon) and tall-grass prairie hay. By the end of the 76-d supplementation period, cows fed PCON (P < 0.01) and NCON (P < 0.01) had gained more BW than cows fed WSUN (33, 23, and 10 kg, respectively). However, from the end of this supplementation period to the beginning of the breeding season 84 d later, cows supplemented with PCON had lost more (P < 0.01) BW than cows supplemented with WSUN (-123 kg vs. -111 kg). Cow BW change through weaning (-50 kg, P = 0.43) and final cow BW (536 kg, P = 0.70) at weaning were not different among supplement groups. Furthermore, cow BCS was similar among supplement treatment groups at the end of the supplementation period (5.3, P = 0.09), at the beginning of the breeding season (4.8, P = 0.38), and at weaning (4.7, P = 0.08). No difference among treatments was detected for calf birth weight (36 kg, P = 0.42), calf weaning weight (235 kg, P = 0.67), percentage of cows exhibiting luteal activity at the beginning of the breeding season (57%, P = 0.29), or pregnancy rate (88%, P = 0.44). However, first service conception rate was greater (P = 0.01) for cows fed PCON (79%) and tended (P = 0.07) to be greater for cows fed WSUN (74%) than for cows fed NCON (53%). After weaning, all steer calves were placed in a feedlot and fed a high-concentrate finishing diet for an average of 188 d. Supplements fed to dams during gestation did not influence feedlot performance or carcass characteristics. Prepartum energy supplementation, regardless of energy source or prepartum energy balance, resulted in improved conception rate, but other measures of reproduction, calf and feedlot performance, and carcass characteristics were not affected.

Effects of prepartum supplementation of linoleic and mid-oleic sunflower seed on cow performance, cow reproduction, and calf performance from birth through slaughter, and effects on intake and digestion in steers1

“…The linoleic and oleic supplements included 0.23 kg/d of the control supplement in an effort to eliminate concerns of reduced palatability of whole sunflower seed. In a previous experiment at our location, some reduced palatability was observed when cows were fed a whole sunflower seed supplement (Banta et al, 2006). The addition of the control supplement eliminated previously observed palatability problems; all supplements were consumed entirely in the current experiment.…”

“…In this experiment, there were no refusals of sunflower supplements. Mixing a soybean hull-based pellet with the sunflower seed apparently eliminated palatability problems that were previously observed when whole sunflower seed was fed to gestating beef cows (Banta et al, 2006). Supplement composition influenced (P < 0.001) BW change during the first 62 d of the supplementation period, before any cows had calved.…”

“…Milk composition was determined on March 7, 2003, using 8 of the earliest calving cows from each supplement (Banta et al, 2006). Cows were selected so that the calving date would be similar among supplements (average calf age = 17 d; range = 10 to 25 d).…”

“…Cows were selected so that calving date would be similar among supplements (average calf age = 50 d; range = 28 to 72 d). Milk production was determined using the weigh-suckle-weigh technique as described previously (Banta et al, 2006).…”

“…The supplements were fed at approximately the same rate as the supplements fed in Exp. 1 and in a previous experiment that we conducted with whole sunflower seed (Banta et al, 2006). Because preexperiment analysis of hay indicated that CP content was low (5.75%, DM basis), each steer received soybean meal at a rate of 0.03% of BW/d in addition to the treatment supplements to ensure that the N requirements of ruminal microbes were met.…”