Maternal energy status during late gestation: Effects on growth performance, carcass characteristics and meat quality of steers progeny.

The objetive of the current study was to determine the effect of maternal energy status during late gestation on growth performance, carcass characteristics and meat quality of steer progeny. At 180 ±â€¯4 d of gestation 56 multiparous Angus cows were blocked by BW and expected calving date and asigned to three levels of nutrition energy: SR (severe restricted; 50% of NRC requirement), MR (moderate restricted; 75% of requirement) and NR (no restricted; 100% of requirement). After parturition, all cows were managed in a single group during lactation. A total of 25 male calves (SR = 8 calves; MR = 9 calves; NR = 8 calves) were born from pregnant cows and all pens had at least one male calf. After weaning, male calves were separated of female calves and were stockered on native range until 24 ±â€¯0.1 months of age then placed into a feedlot for 104 d before harvest. Cow BW and BCS decreased linearly (P < .01) as nutritional energy restriction increased. Calves from SR dams were lighter (P = .04) than calves from MR and NR dams at parturition, however, at weaning and harvest BW was similar for SR and NR steers and decreased in MR steers. Steers from SR dams demonstrated catch-up growth with a tendecy to increased ADG from birth to harvest compared to MR and NR steers (P = .06). Hot carcass weigth was similar in SR and NR steers and increased in MR steers (P = .01). Longissimus muscle area was not affected (P > .10) by maternal energy status, however, 12 rib fat thickness was greater in SR and MR compared to NR steers (P < .01). Tenderness of Longissimus muscle was decreased in MR compared to SR and NR steers after 3d of aging. No treatment differences (P > .10) were observed in sarchomere length or collagen content. Adipocyte diameter was similar (P > .10) between treatments suggesting that decreased 12th rib fat thicness in MR steers could be due to decreased fat tissue hyperplasia. These results indicate that level of energy restriction during late gestation does no have linear response on growth performance and carcass quality of steers progeny.

The influence of protein restriction during mid- to late gestation on beef offspring growth, carcass characteristic and meat quality.

The objective of this study was to determine whether crude protein intake during the last three months of gestation affects growth performance, carcass characteristics and meat quality of steer progeny. At 134 ±â€¯14 d of gestation, 68 multiparous Angus cows were blocked by BW and expected calving date and randomly assigned to diets that contained either low or high dietary crude protein concentrations and were allotted in 12 pens per treatment. After calving, cows were managed together on improved pastures during lactation. After weaning at 219 ±â€¯13 d of age, steers calves were stockered on natural pastures until 687 ±â€¯13 d of age then placed into a feedlot for 83d before slaughter. Maternal dietary protein concentration had no influence on offspring body weight and growth rate during rearing or finishing phases (P > .10). Rib fat thickness of steers was not affected (P = .38) by maternal nutrition treatments, however, LM area was greater in HP steers than LP steers at entrance into the feedlot (P = .01) and end of finishing phase (P = .04). Hot carcass weight was similar between treatments (P = .69), however dressing percentage was increased in HP relative to LP steers (P = .01). Tenderness of Longissimus muscle was increased in HP compared to LP steers after 3 and 14d (P < .001) of aging. No treatment differences in troponin-t degradation (P = .77) and collagen content (P = .58) were observed. Muscle fiber diameter was similar in LP and HP steers (P = .20), suggesting that increase of LM area in HP steers could be due to muscle hyperplasia. These data indicated that level of protein during mid to late gestation does not affect offspring growth but has impacts on carcass composition and meat quality of steer progeny.