Effect of beef heifer development systems utilizing corn residue and late summer planted cover crops on growth, reproductive performance, and economics.

The objective of this study was to evaluate growth and reproductive performance of heifers developed using 3 different winter systems in the midwestern U.S. Spring-born heifers (n = 1,156; 214 d of age; SD ±â€…17 d) were used in a 3-yr study to evaluate performance in winter development systems, which utilized cover crop (CC) and corn residue grazing. Heifers were assigned to 1 of 3 treatments: grazing corn residue with 0.77 kg/d dried distillers grains (CD) or 1.69 kg/d wheat midds (CW) supplementation followed by a grower ration in the drylot, or grazing late summer planted oat-brassica CC followed by corn residue grazing with 0.35 kg/d dried distillers grains supplementation (CC). Supplementation during the corn residue phase was targeted to result in a common body weight (BW) (276 kg; ~45% of mature BW) by the end of the winter development period. Grazing of corn residue (CD and CW) and CC began in early November. After 63 d, heifers assigned to CC were moved to corn residue; on day 77 heifers assigned to CD and CW began receiving a grower ration in the drylot. In mid-February (day 98), heifers were comingled and managed in a single group. Breeding season began in June and lasted for 29 d. The ADG of heifers assigned to CC when grazing CC (days 1 to 63) was greater (0.76 kg/d; P < 0.01) than those assigned to CD or CW (0.58 kg/d and 0.49 kg/d, respectively). Gain during the last 35 d of the winter period for heifers assigned to CC (0.36 kg/d) was less (P < 0.01) than those assigned to CW (0.49 kg/d) but not different from CD heifers (0.41 kg/d). Overall (days 1 to 98), winter ADG was greater (P < 0.05) for heifers assigned to CC (0.62 kg/d) than CD (0.53 kg/d) or CW (0.50 kg/d), which did not differ (P = 0.42). Percent of mature BW in May (27 d pre-breeding) was greater (P < 0.01) for heifers assigned to CC (52%) than for those on CD and CW (50%), which did not differ (P = 0.64). Pregnancy rates were affected by treatment (P < 0.03), with heifers assigned to CC (76%) being greater than CW (64%) and CD heifers being intermediate (70%). When accounting for the differences in cost and the value of open and bred heifers, the economic return tended to differ (P = 0.07) among treatments, with CC and CW not differing (P ≥ 0.20) from CD but return for CC being $73 greater than CW (P = 0.02). Utilizing oat-brassica CCs early in the winter followed by a slower rate of gain while grazing corn residue with distillers supplementation appears to be as effective for developing beef heifers in the midwestern U.S. as supplementing distillers grains.

Factors affecting economics of using sexed semen in dairy cattle.

The use of sexed semen in the dairy industry has grown rapidly. However, high costs and low fertility have limited the use of this potentially valuable tool. This study used simulation to evaluate 160,000 combinations of key variables in 3 spheres of influence related to profit feasibility: (1) market (e.g., milk and calf prices), (2) dairy farm management (e.g., conception rates), and (3) technology (e.g., accuracy of sexing). These influential variables were used to determine the most favorable circumstances in which managers or technicians can effect change. Three distinct scenarios were created to model 3 initiatives that a producer might take with sexed semen: (1) using sexed semen on heifers, (2) using sexed semen on heifers and a fraction of the genetically superior cows, and (3) using sexed semen on heifers and a fraction of the genetically superior cows, and breeding all other cows with beef semen. Due to the large number of management, market, and technology combinations, a response surface and interpretive graphs were created to map the scope of influence for the key variables. Technology variables such as the added cost of sexed semen had relatively little effect on profitability, defined as net present value gain per cow, whereas management variables such as conception rate had a significant effect. Milk price had relatively little effect within each scenario, but was important across scenarios. Profitability was very sensitive to the price of dairy heifer calves, relative to beef and dairy bull calves. Scenarios 1 and 2 added about $50 to $75 per cow in net present value, which ranged from $0 to $200 and from $100 to $300, respectively. Scenario 3 usually was not profitable, primarily because fewer excess dairy replacement heifers were available for sale. Dairy heifer price proved to be the most influential variable, regardless of scenario.

Forages and pastures symposium: cover crops in livestock production: whole-system approach. Can cover crops pull double duty: conservation and profitable forage production in the Midwestern United States?

Data from a recent survey suggest that the major reasons Nebraska farmers plant cover crops are to improve soil organic matter, reduce erosion, improve soil water holding capacity, produce forage, and increase soil microbial biomass. Many of these benefits appear to be positively correlated with production of above-ground biomass. Thus, selecting species that will produce the greatest biomass should be beneficial for both soil conservation and forage production. Furthermore, the limited data available suggest that grazing of cover crops does not have large negative crop production, soil, or environmental impact. In the Midwestern United States, the production window following wheat harvest, male row destruction in seed corn, and to a lesser extent following corn silage harvest is long enough to produce 2,500 to 4,500 kg DM per hectare of high-nutritive value, fall forage. In the past 4 yr, we have conducted eight trials using predominantly oats and brassicas planted in mid- to late-August. Forage nutritive value of oats and brassicas is extremely high in early November (70% to 80% IVDMD; 14% to 23% CP) and remains high through December with only a 4% to 7% unit decrease in IVDMD and no change in CP concentration. Thus, it appears that delayed grazing could be an option to maximize potential forage yield. Fall-weaned calves (200 to 290 kg BW) grazing oats with or without brassicas in November and December (48 to 64 d) at stocking rates of 2.5 to 4.0 calves per hectare have ADG between 0.60 and 1.10 kg. The cost of gain has ranged from $0.53 to $2.08/kg when accounting for seed costs plus establishment ($60 to 117/ha), N plus application ($0 to 58/ha), fencing ($11/ha) and yardage ($0.10 calf-1 d-1). Although soybeans and corn harvested for grain do not provide a large enough growing window to accomplish fall grazing, similar dual purpose cover crop practices are often accomplished by planting winter-hardy small grain cereal grasses, such as cereal rye or winter triticale in the fall and grazing in the spring. However, traditional planting dates for corn and soybean result in a 30 to 45 d grazing period prior to corn and a 45 to 60 d period prior to soybean planting. Planting cover crops to provide late fall or early spring grazing has potential. However, incorporating forage production from cover crops into current cropping systems greatly increases the need for timeliness of management since the window of opportunity for forage production is quite narrow.