Researchers are hoping to shed new light on a method for turning beef heifers into better cows.
A study is planned that explores the effects of extra light on beef heifers housed outdoors in the winter. The study is being led by Julie Small, a scientist in beef reproductive management at Agriculture Canada’s research centre in Brandon, Man.
The research will begin this winter with 144 heifers. They will be separated into two groups, with only one of the groups exposed to the extended lighting. Both groups will be penned in open lots with southern-exposed shelters.
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“We’re trying to find the best way to raise these heifers so that you’re getting a good cow,” Small said. “The extra light may improve their mammary gland development, which would mean they’d have higher milk production and wean a better calf.”
It’s also hoped that artificial lighting will improve the pregnancy performance of the heifers. The lighting used in the study is comparable to that of an office with fluorescent lights.
A recent study in the United Kingdom looked at the effects of supplemental light on dairy heifers. Findings from the study suggest 16 hours of daylight can induce puberty at an earlier age and body weight, while increasing the animals’ sexual activity.
During the study at Brandon, the two groups of heifers will be monitored for the regularity of estrus, which begins once they reach puberty. Body weights and fatness scores will also be recorded.
The heifers will be synchronized for artificial insemination at 14 to 15 months old. Blood samples from the animals will be analyzed for concentrations of the hormones progesterone and prolactin.
Progesterone would confirm ovulation and pregnancy, while prolactin would help reveal any physiological effects of the supplemental light. Prolactin plays a major role in mammary gland development.
“Prolactin is sensitive to light,” Small explained. “It’ll be a guide as to whether we need more light or whether we have enough.”
Early pregnancy
If the supplemental lighting proves effective, Small believes it would be readily adopted for larger commercial and purebred operations as well as custom heifer development services provided by beef test stations. It could then be used to promote the early onset of puberty and help establish pregnancy at 15 months of age, a goal among beef producers.
A recent survey found that 67 percent of Manitoba beef producers had a calving season that started in January and ended in May. That can translate into increased labor costs for calving, a less uniform calf crop and prolonged calving intervals.
The Brandon research centre hopes to eventually learn what amount of supplemental light is most effective and economical. That research will be done in coming years, once the results of the current study are known.
Small said they will look at whether it’s necessary to simulate dawn and dusk, whether to introduce the light gradually or in an on/off fashion, and what intensity of light will bring the best results.
Manitoba Hydro is providing lighting equipment and sponsorship of a post-graduate student, Nanette Glover.
