Protein supplementation increases forage intake and digestibility, while improving lactation and enhancing reproduction.
New Mexico State University scientists, working with USDA Agricultural Research Service (ARS) and the University of Missouri, tested whether, after requirements for degradable intake protein (DIP) have been met, additional protein supplied as undegradable intake protein (UIP) alters the metabolic and endocrine factors associated with reproduction in beef heifers.
Twenty-three yearling heifers were assigned one of three groups: low UIP, mid UIP and high UIP, and estrually synchronized before initiation of supplementation. Supplement was fed for 30-32 days before the heifers were harvested and tissues collected.
Scientists found that low and mid levels of UIP supplements fed to estrous cycling beef heifers seemed to enhance pituitary expression and/or secretion of follicle stimulating hormone (FSH) relative to high levels of UIP. High levels of UIP were also associated with increased low-molecular weight compared to supplementing low or mid UIP.
UIP supplementation has been reported to enhance reproductive performance by minimizing body weight changes, hastening the onset of puberty, decreasing postpartum anestrous and increasing pregnancy rates of cows consuming dormant forage. However, high rates of UIP have also been associated with impaired fertility in beef cattle.
This study suggests alterations in reproductive performance with UIP supplementation in beef cattle may be associated with changes in the anterior pituitary gland synthesis, storage and secretion of gonadatropins and/or ovarian follicular dynamics, thereby influencing the reproductive performance of heifers.
J. Anim. Sci., Jan., 2004. 82:283-291
Nutrition that restricts cattle growth and limits body fat deposition doesn't affect cattle's gain and efficiency performance in the feedlot.
Animal scientists at Oklahoma State University and the ARS Grazing Lands Research Laboratory in El Reno, OK, conducted two experiments with 48 steer calves in each. The purpose was to compare the effect of previous body weight gains and body composition resulting from winter grazing programs on subsequent feedlot performance, carcass characteristics and change in body composition in the finishing phase of production.
The calves were assigned randomly to three treatments: high rate of body weight gain grazing winter wheat, low rate of body weight gain grazing winter wheat, and grazing dormant tall grass native range supplemented with cottonseed meal.
At the end of winter grazing, four steers from each treatment were harvested to measure initial carcass characteristics. Remaining steers were fed a high-concentrate diet to a common backfat end point. Carcass characteristics and chemical composition were then measured.
Results showed differences in average daily gain during winter grazing and initial body fat content didn't affect the rate of live body weight gain or gain efficiency during finishing. Feeding steers to a common backfat thickness end point mitigated initial differences in carcasses.
The study showed, however, that maintenance energy requirements during finishing were increased for nutritionally restricted steers that were wintered on dormant, native range.
J. Anim. Sci., Jan. 2004. 82:262-272
Scours in a calf will significantly impact the animal's eventual weaning weight, Montana State University (MSU) researchers found.
The MSU researchers evaluated the health and performance records of 3,637 calves from inbred and outbred populations over a 14-year period. The inbred cattle were linebred Herefords, while the outbred cattle consisted of four genotypes: Hereford, Angus x Hereford, Simmental x Hereford, and Tarentaise x Hereford.
Over the 14-year period, average incidence of scours was 35%, with a range of 13% to 64%. Incidence of scours was significantly higher for inbred than outbred calves (41% vs. 28%). Meanwhile, incidence of scours was significantly higher in calves born to two-year-old dams and decreased with increasing age of dam.
The researchers found that, over all years, scouring calves weighed 458 lbs. at weaning. Meanwhile, non-scouring calves weighed 478 lbs. In addition, outbred calves were significantly heavier than inbred calves (483 lbs. vs. 452 lbs.).
|Acres/exposed female||21.3 A|
|Female replacement rate||19.7%|
|Avg. age at weaning||199 days|
|Avg. weaning wt. per calf||519 lbs.|
|Lbs. calf weaned/female exposed||451 lbs.|
|Total assets/beginning year female||$2,087|
|Total expenses/beginning year female||$397|
|Total revenue/beginning year female||$430|
|Return on assets||3.1%|
The authors concluded that the economic benefit of managing to reduce incidence of scours should exceed the expense to reduce the economic loss that can occur when calves are afflicted with scours.
Anderson et al. 2003. Prof. Anim. Sci. 19: 399
South Dakota State University researchers recently developed benchmark data for Northern Plains herds. The researchers summarized data collected and analyzed by Standardized Performance Analysis (SPA) guidelines from 185 cooperating cow herds during the years 1991-1999. The states involved included North Dakota, South Dakota, Wyoming, Minnesota, Iowa, Nebraska and Kansas (Table 1).
The operations were large by industry averages, and averaged 508 breeding females. Besides production data, 148 of the cooperators provided financial information.
Though the results aren't necessarily applicable to other regions, they do offer benchmark data regarding practices, production levels and financial performance. Table 1 is an abbreviated summary of the results.
Dunn et al. 2003. South Dakota Beef Report