In our practice experience, increased forage intake from conserved feed or pasture has a profound influence on reproductive health without decreased milk production. Originally, we attributed this to reduced acidosis and its common aftermath, such as lameness and low feed intake. However, forages are also high in omega-3 fatty acids.
Feeding a high-forage ration can alter the ratio of omega-6 to omega-3 fatty acids in the diet. In a typical corn-based diet, the range of omega-6 to omega-3 can be 12 or even 20:1 compared to 2:1 or less in a high-forage ration.
On the human side, research has shown that a low omega-6-to-omega-3 ratio in the diet protects against many inflammatory diseases. Perhaps the same is true in cows.
New Canadian research reported in the August 2006 issue of the Journal of Dairy Science showed remarkable increases in fertility of dairy cows fed omega-3 polyunsaturated fatty acids. Previous studies used fish oil or fish meal as a source of these long-chain omega-3 fatty acids, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Fish oil was found to reduce prostaglandin synthesis from the uterus, delay regression of the corpus luteum, and improve pregnancy rates in lactating dairy cows.
About one in four survive
Decreasing fertility in dairy cows is a great concern to the industry. Losses in the modern dairy cow are greater at every step in the process from ovulation to parturition. Estimates are that the fertilization rate in dairy cows is only 75 percent to 80 percent. In heifers and beef cows, this number is closer to 100 percent.
The effects of negative energy balance after calving and heat stress on the follicle prior to ovulation can cause poor oocyte quality. And, research has shown that total fetal and embryonic losses from conception to birth results in birth rates of about 28 percent from an appropriately timed and accurately performed insemination.
Omega 3 can help
This new research, conducted by Divakar Ambrose and colleagues at the
Here"s what they found:
Conception rates at day 32 were 48.4 percent for cows fed flaxseed and 32.2 percent for cows fed sunflower seeds.
From days 32 to 90, embryo loss was 4.8 percent in the flaxseed group versus 11.4 percent in the sunflower-seed group. (Premature elevation in uterine prostaglandin and loss of the corpus luteum can result in fetal loss at any stage.)
After 90 days of gestation, the flaxseed group continued to show protective effects for the developing fetus. Additional losses through calving were 5.1 percent in the flaxseed group versus 17.2 percent in the sunflower-seed group.
From the initial 121 cows split randomly into two treatment groups, 39 calves were born in the flaxseed group compared to 26 calves in the sunflower-seed group.
These findings add strength to the growing body of research that shows dietary fatty acids enhance reproductive performance in cattle.
Meg Cattell is a consulting veterinarian and organic dairy producer in
This article is available in Spanish at edp.dairyherd.com.