Late gestation nutrition has a large impact on multiple aspects of the cow’s productivity after freshening, says Charles T. Estill, VMD, PhD, Dipl. ACT, Oregon State University. “The health and viability of the neonate are directly affected,” Estill says, speaking at the 2011 Western Veterinary Conference. “In addition, colostrum quality and quantity are influenced by prepartum nutrition. Early lactation milk yield and milk components are largely a reflection of prepartum nutritional management.” Estill adds that the incidence of metabolic and infectious disorders can be minimized through proper nutritional management of the transition cow. Fertility of the dam is strongly correlated with late gestation and early postpartum nutrition.
The start of the transition period begins three weeks before anticipated calving date and ends three or four weeks after freshening. “Protein intake must be adequate to support fetal growth and maintenance of the dam,” Estill explains. “As a monitor, blood urea nitrogen (BUN) can be examined and should be 9-12 mg/dL. In general, absorbed protein should be +200-400 g/d (Spartan Ration Balancer).” The nonstructural carbohydrates (NSC) concentration should be at 30-35 percent to stimulate microbial protein synthesis and rumen papillae development. Papillae development is stimulated by propionate (from fermentable starch) and takes about four weeks to occur. It is also very important to avoid excessive NSC or fatty liver will result.
There are several serious consequences of low protein/energy intake during the close-up dry period. “Insulin concentrations will decline leading to increased protein catabolism and reduced protein synthesis,” Estill says. “Somatotropin concentration will be elevated which increases protein synthesis but redirects protein away from muscles toward other tissues such as the conceptus and mammary gland which results in a depletion of body protein reserves.” It is important to avoid extremely high fiber diets during the close up dry period because DMI will be reduced due to physical fill and reduced transit time. Very high energy diets resulted in a substantial decline in DMI prior to calving and should also be avoided.
General guidelines for a close up dry cow ration are:
- 12-15 percent CP (14 percent min if heifers in with close up cows) – increase RUP to 35-38 percent
- NEL,Mcal/lb 0.68-0.72
- 33-35 percent NSC
- 35-40 percent NDF
- Forage >70% of diet
- Ca≤6 percent or ≥1.3 percent if feeding anionic salts, Mg 0.35-0.40 percent
- K<1.2 percent , P<0.35 percent (<50 g/day)
- Increase trace minerals 20-50 percent above NRC and force feed
- Consider chromium propionate at 500 ppb for heifer diets
- Increase omega-3 fatty acidcontent of feed but do not raise overall lipid concentration to over 3-4 percent
- Vitamin E 1000-2000 IU/day
- Niacin 6-12g/hd/day