Though conventional dairying wisdom usually says to feed cows plenty of high-energy feedstuffs prior to calving, a University of Illinois study finds it could have a better eventual payoff if you don't.
Animal sciences researcher Phil Cardoso explains that that payoff can come in the form of quicker pregnancies after calving and less loss of body condition – along with a host of other benefits.
Using data from seven University of Illinois experiments from 1993 to 2010, Cardoso constructed a database of 408 cows containing data on prepartum diet and physiological status. He also looked at days to next pregnancy after calving, which had not been considered in previous studies.
Cardoso found that on average, cows fed 80% of the recommended amount of feedstuffs became pregnant 10 days sooner than cows fed high-energy diets.
"People say that if you give this (controlled energy) diet, the cows don't get pregnant, but that's not true," he said. "If anything, they are a little better off."
Cardoso said that the shorter time to conception for cows fed the CE diet is due to the fact that they eat more after calving than the cows fed the HE diet.
"We want the cow to eat as much as possible just after calving because then she's going to be healthier," Cardoso said, explaining that after cows calve, they have a negative energy balance. This is because they cannot consume enough energy to compensate for the fact that they are producing milk.
Cardoso also discovered that because they were eating more following calving, the cows in his study also lost less in body condition and had a lower disease incidence.
Another perk? The researchers also noticed that cows fed the CE diet showed less prepartum versus postpartum variation in how much they ate. By contrast, the cows fed the high energy diet were eating more than they needed before calving.
In a follow-up study that has not yet been published, the researchers tried to strategies to make the cows eat less. One was to give them just 80% of what they needed; the other was to increase fiber in the day so the diet would be lower in energy and the cows could eat more. They had similar results for the two strategies.
There are indications that a CE diet has other benefits. It may help food to remain longer in the rumen, which is beneficial to the cow if she is stressed.
In short, Cardoso advised, just give the cow what she needs and she will perform better metabolically and reproductively.
Source: University of Illinois
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