Serving to cows deal with chilly stress
6 min read
Chilly stress will increase a cow’s vitality requirement and might pull down her physique situation. Skinny cows can lead to weak calves being born within the spring and/or poor breed up. Winter storms have already swept throughout the Plains, giving indications this could possibly be a protracted, chilly winter for cows already skinny attributable to summer season drought stress.
The edge at which cattle have to start out utilizing vitality to keep up their physique temperature is known as the decrease vital temperature (LCT). Cows in good situation (BCS 5.0; 1-9 scale) which have a heavy winter coat that’s dry don’t want to make use of vitality to keep up physique temperature till the wind chill index is under 19°F. Providing wind protection can lower vitality wants by eradicating wind as an element. If cows have safety from wind, then the ambient temperature can be utilized to find out vitality wants. So, offering wind safety within the winter may be big for decreasing supplementation wants attributable to chilly within the winter.
To determine how way more vitality a cow wants, you’d take the cow’s LCT minus the wind chill index (if no windbreak is offered) or ambient temperature (if wind break is offered) and that will let you know the p.c enhance in vitality requirement. There’s a 1% enhance in vitality wants for each 1° under the LCT. As an illustration, if ambient temperature is 21°F and wind velocity is 10, the wind chill index (WCI) is 11°F. For a BCS 5 cow with a dry winter coat with a LCT of 19°F, then 19 LCT- 11 WCI = 8% enhance in vitality wants. You’ll be able to lookup the vitality wants of varied courses of cattle here. A 1200 lb dry cow in late gestation has an vitality requirement of 13 lb whole digestible vitamins (TDN) and the chilly described above elevated this want by an extra 8% which is the same as 1 lb of TDN for a complete of 14 lb/d.
Skinny Cows: A Snowball Impact
It is crucial that producers assess physique situation rating now, as many cows got here by way of the autumn skinny (< BCS 4) and winter has had an early begin in lots of areas. Physique situation is a threat administration technique and impacts the LCT. A skinny cow with a BCS 4 with a dry winter coat has a LCT of 27°F vs the 19°F of a cow in BCS 5. Thus, if the wind chill index was 19°F, a cow in BCS of 5 wouldn’t be utilizing any vitality to remain heat and a cow with a BCS 4 could be utilizing 8% extra vitality to remain heat. So, getting cows into good situation early within the winter may be helpful for managing threat of unhealthy climate in that they’ve situation they’ll lose but in addition as a result of cows with larger BCS will lose much less with the identical quantity of vitality consumption than these with decrease physique situation. A 1200 lb gestating cow can solely eat about 31 lbs of medium high quality hay which is about 26 lbs DM. If you happen to fed medium high quality hay (53% TDN on DM foundation) to a cow that was in a BCS of 4 when the windchill was 19°F, she wouldn’t have the ability to eat sufficient hay to fulfill her vitality wants and could be shedding pounds whereas the BCS 5 could be gaining a little bit situation. A sensible administration technique could also be to contemplate placing skinny cows in a gaggle together with your first calf heifers as each have larger vitality requirement within the winter, which might permit for strategic feeding of upper high quality forage or supplementation when out grazing.
Moist Hair Coats End in Large Vitality Loss
It’s also essential to know {that a} moist hair coat forward of a snowstorm exacerbates the scenario. A moist coat will increase the LCT of a cow in good situation to 53°F. Thus, basically anytime a cow’s coat is moist within the winter, they are going to be utilizing vitality to keep up physique temperature. Subsequently, in winters with extra precipitation, particularly freezing rain, we frequently see better decreases in BCS.
Assembly Cow’s Vitality Wants Throughout Chilly Stress
It isn’t advisable to alter rations day by day however for prolonged chilly and/or moist intervals take into account feeding extra of the identical ration, assuming cattle can eat extra of the everyday ration. If not, then offering a complement is a good suggestion. When feeding decrease high quality hay, dormant vary grazing or corn stalk grazing, further feed can be wanted. One possibility is to alter to feeding a better high quality hay supply, if obtainable. Free selection top quality hay (58 to 60% TDN) can work right down to temperatures of 34°F under the LCT of the cow (or -15°F for cows in good situation with dry hair or 19°F with moist hair). If cows are grazing, then supplementation with a excessive vitality feed could also be fascinating. Whereas corn can be utilized to supply extra vitality, it comes with threat. Feeding greater than 2 to three lbs/hd can lower forage digestion, particularly if the forage is decrease in protein. Feeding corn with some alfalfa on low protein forges can mitigate this challenge. With 3 lbs of corn one may make up the distinction of about 15 levels F between the LCT of the cow and the wind chill index temperature, which for a cow in BCS of 5 with a dry coat, corn supplementation would cowl the elevated vitality requirement down to five°F or for a cow with a moist hair coat to solely about 38°F.
Distillers grains are an alternative choice. Distillers is a good source of energy. It has extra vitality than corn, and since it’s excessive in protein, it doesn’t trigger as a lot of a substitution impact (is not going to lower consumption of the forage a lot). Within the instance above the place the cow wanted an additional 1.2 lbs of TDN, feeding 1.2 lbs (as-fed) of dry distillers would supply the additional vitality wanted. Within the case of distillers and gestating cows, the kilos of TDN wanted to account for vitality used attributable to chilly stress could be equal to the kilos of dry distillers that will should be fed. Limitations on the quantity of distillers that could possibly be fed could be extra primarily based on budgetary considerations than digestive results.
When wind chill temperatures are extraordinarily chilly or the cow has a moist hair coat, a number of complement could be wanted to make up the better vitality wants and keep physique situation. As an illustration, if the wind chill was -10°F and the cows had a moist hair coat, then 8.9 lbs of dry distillers could be wanted to account for the elevated vitality requirement. Nonetheless, feeding these ranges is probably going impractical. A greater method could be to supply a smaller quantity of supplemental feed and to proceed to feed the additional feed after the climate has moderated to permit cows to regain vitality misplaced through the storm.
It’s also essential to keep in mind that lactating cows have a much greater energy requirement than pregnant cows. Given this, the mixture of chilly stress and lactation can pull down BCS shortly. If lactating cows are additionally subjected to chilly stress, growing their vitality consumption previous to observing lack of situation is advisable.
Searching for extra data? Take a look at the webinar Caring for Cattle in Cold Weather.
