Influence of excessive dietary protein intake during late gestation on drylot beef cow performance and progeny growth, carcass characteristics, and plasma glucose and insulin concentrations

Spring-calving cows (n = 49) were used to investigate the effects of excessive prepartum dietary protein intake on late gestation cow performance as well as subsequent progeny growth, carcass characteristics, and plasma glucose and insulin concentrations. Treatments were formulated to be isocaloric and provide 100% (REQ) or 129% (HP) of CP requirement. Treatments were limit-fed 78 +/- 12 d prepartum to calving. All cows were fed a common diet postpartum. Cow BW and BCS were recorded at initiation of treatments and within 48 h post-calving. Milk production was estimated via the weigh-suckle-weigh technique 69 +/- 11 d postpartum. Calf BW was measured at birth and at weaning (121 +/- 11 d of age). Progeny (n = 42) were weaned as a group and placed into a feedlot and fed a common finishing diet. Glucose and insulin concentrations were analyzed on a subset of progeny (12 per treatment) 90, 120, 150, 180, 210, and 240 min post-feeding, 2 d before slaughter (342 +/- 11 d of age). Treatment had no effect (P >= 0.22) on cow BW, BCS, milk production, and subsequent reproduction or progeny preweaning growth. Progeny finishing growth and marbling scores were not affected (P >= 0.24) by treatment, yet 12th rib fat thickness (P < 0.01), KPH (P <= 0.04), and YG (P = 0.01) were greater for progeny born to HP dams. Progeny born to HP dams had decreased (P. 0.01) glucose and insulin concentrations, and insulin to glucose ratios, indicating greater insulin sensitivity. Although feeding cows 129% of CP requirement during late gestation did not affect cow performance or progeny preweaning or finishing period growth; carcass adiposity was increased by maternal treatment.