Byproduct feeds for gestating cows
With calving season rapidly approaching for spring-calving cows, nutrition becomes critical. Research has shown that a cow’s body condition at calving is a good indicator of her ability to cycle and breed back in a timely manner. But given the high price of high-quality hay in many areas, producers might be looking for ways to boost the nutritional value of lower-quality feeds such as wheat straw. Depending on local availability, byproduct feeds such as beet pulp or distillers’ grains could fit the bill, based on University of Nebraska research.
The researchers conducted two experiments to evaluate feeding wheat straw supplemented with distillers’ grains or distillers’ grains and beet pulp, compared with feeding alfalfa hay to late-gestation cows.
For the first experiment, the researchers prepared a high-moisture combination of 30 percent wet distillers’ grains plus solubles (WDGS) and 70 percent ground wheat straw three months ahead of the test and stored the feed in agricultural bags. They randomly sorted 40 pregnant cows into eight five-head pens, with half of the pens receiving the mixed feed and the other half receiving ground alfalfa hay. They limit-fed both groups for 77 days, with the diets formulated to meet the cows’ energy needs.
They ended the experiment two weeks prior to calving and measured initial and ending body weights, initial and ending body condition score (BCS) and calf birth weights.
In this trial, average weight gain over the 77 days for cows receiving the wheat straw-WDGS mix was167 pounds compared with 144 pounds for the group receiving alfalfa hay. Change in BCS and calf weights did not differ between the groups, and the researchers concluded the stored mix of 30 percent DDGS and 70 percent wheat straw can maintain body weight and BCS in gestating cows.
In the second experiment, the researchers sorted 57 cows into pens receiving one of three rations:
- Ground alfalfa hay
- 30 percent WDGS and 70 percent wheat straw
- 20 percent WDGS, 20 percent beet pulp and 60 percent wheat straw
In this case, all the rations were mixed and fed fresh, rather than mixed and stored like in the first trial. The researchers limit-fed each treatment group for 84 days, with rations formulated to meet the cows’ energy needs.
They ended the experiment four weeks before calving and measured initial and ending body weights, body weight change, BCS change and calf birth weights.
In their report, the researchers note that the alfalfa used in this trial was not as high in digestible energy as they initially estimated, so the energy level in the alfalfa diet was somewhat lower than the other two treatments. Weight gains for the cows on the alfalfa treatment averaged 66 pounds compared with 147 for those on the WDGS-wheat straw diet and 162 pounds for those on the WDGS-beet pulp-wheat straw diet.
Average BCS scores for cows on the alfalfa diet were 5.3, and cows in this group lost an average of 0.4 BCS through the course of the trial. Cows in the WDGS and beet pulp groups finished the trial at BCS 5.7 and 5.8 respectively, and maintained BCS through the trial. The researchers conclude that cows in late gestation will maintain body weight and BCS when limit-fed WDGS and beet pulp mixed with wheat straw to meet their energy requirements.