Supplementation to meet metabolizable protein requirements of primiparous beef heifers: II. Pregnancy and economics1

Abstract

Metabolizable protein (MP) requirements of spring calving heifers increase over the winter due to advancing gestation. The MP content of grazed winter forage is low, which may result in an MP deficiency. The objective was to compare the response of supplementing pregnant yearling heifers to meet MP requirements versus conventional CP supplementation. In 1997-98 and in 1998-99, pregnant, March-calving heifers (2,120 animals; 358 kg) at two locations of a commercial ranch in the Nebraska Sandhills, were used following breeding through calving as 2-yr-olds (cows). Heifers were randomly allotted to one of two supplementation treatments (about 265 heifers/treatment) each year at each of two locations (Ashby and Whitman, NE). Treatments were 1) supplementation to meet MP requirements (MPR) or 2) supplementation to meet CP requirements (CPR). Heifers grazed upland range and meadow and were offered supplements three times weekly from mid-September to mid- or late-February. Increasing amounts of meadow hay were fed from mid-December through calving. After supplementation ended in February, heifers were managed in one group at each location until the following October. Body weights and body condition scores were taken in September, February, and October. Two-yr-old pregnancy rates were determined via rectal palpation in October. Capital budgeting techniques were used to determine the economic return of supplementation strategies. There were no differences in BW (P = 0.41) or body condition score (P = 0.99) change during the winter among treatment groups across years and locations, but MPR cows were heavier (425 kg) than CPR cows (421 kg) at the time of 2-yr-old pregnancy testing (P = 0.07). Pregnancy rate was higher (P = 0.001) in the MPR (91%) compared to the CPR treatment (86%). Regression analysis showed that the response of the MPR treatment on pregancy rates tended to be negatively correlated with precalving body condition score (P = 0.11), body condition score loss over the winter (P = 0.07), and body condition score at weaning of the first calf (P = 0.08). The improvement in 2-yr-old pregnancy by supplementing to meet MP requirements improved the value of each bred heifer by 13.64 dollars. We conclude that balancing MP requirements during gestation may result in a subsequent increase in 2-yr-old pregnancy and increase the value of young females.

Application of the 1996 NRC to Protein and Energy Nutrition of Range Cattle

“…The supplement designed to meet CP requirements was based on cottonseed and soybean meal and supplied 57 g of UIP/d from October to February. The supple- A simultaneous study on a commercial ranch (Patterson et al, 2003a) used 2,120 gestating heifers over 2 yr and 2 locations to evaluate effects of supplement protocols designed to meet either CP or MP requirements (supplement regimens as described above for Patterson et al, 2003b). Heifers calved in March and April, and subsequent 2-yr-old pregnancy rates were measured each year.…”

“…In recent work at Nebraska and North Dakota, protein degradability of diets collected by cows grazing Northern Great Plains Rangeland was analyzed (HollingsworthJenkins et al, 1996;Lardy, 1997;Johnson et al, 1998;Lardy et al, 1999;Patterson et al, 2000Patterson et al, , 2003a. These studies, which used various methods of estimating protein degradability and included both cool-and warm-season grasses, revealed the UIP content of dormant forage ranged from 0.5 to 2.0% of OM.…”

“…Using the NRC model, 53 individual diet calculations were made with experimental diets from 10 published studies (Adams et al, 1989(Adams et al, , 1993Hollingsworth-Jenkins et al, 1996;Lamb et al, 1997;Lardy et al, 1997;Villalobos et al, 1997;Lardy et al, 1999;Ciminski et al, 2002;Jordan et al, 2002;Patterson et al, 2003a) to evaluate MP balance. Of the 53 diets evaluated, 47 had negative MP balances.…”

Role of Minerals in Reproductive Health of Dairy Cattle: A Review

“…Deficiency of cobalt will in turn lead to Vitamin B12 deficiency. Manganese, zinc and iodine may reduce cobalt deficiency (Patterson et al, 2003). The dietary requirement of cobalt for dairy cattle is 0.11ppm (Miller et al, 1998).…”

Influence of Distillers Dried Grain Supplementation Frequency on Forage Digestibility and Growth Performance of Beef Cattle

“…Energy is supplied in the form of highly digestible fiber and fat and does not contain nonstructural carbohydrates (Stock et al, 2000). Additionally, DDGS is an ideal supplement for growing cattle consuming foragebased diets because of high RUP (Klopfenstein, 1996;Patterson et al, 2003) and phosphorous (McDowell, 1996) content.…”