It may be hard to believe, but summer is just around the corner. Now is the time to think about ways to minimize the negative effects of hot weather on sow feed intake during lactation. A summer lactation diet can keep nutrient intake up even when feed consumption is down. In addition, there are many management techniques (i.e. drip coolers, proper ventilation rates, etc.), which can help minimize reduced lactation feed intake during the summer months.
Why is maintaining lactating sow feed intake during hot weather so important?
The sow is very committed to her pigs and will do everything she can to meet their need for milk. This includes mobilizing nutrients from her body. A sow with a litter of 10 pigs produces an average of 20 to 25 lb. (~2.5 to 3 gallons) of milk per day. To produce this quantity of milk, a typical sow consumes an average of 12 pounds of feed per day during lactation. This level of feed intake still requires the typical sow to mobilize some nutrients from her body, which results in some weight loss. However, this level of weight loss is normal and has little influence on the performance of sows. If feed intake is reduced too much (i.e., hot weather), the sow is required to mobilize excessive amounts of nutrients from her body, which can have negative effects on the performance of sows.
What are the negative effects of reduced feed intake during the summer on sows?
Excessive weight loss of sows is the key negative result from reduced feed intake during the summer. Remember, the sow will do anything within her ability to support the milk needs of her piglets, including excessive mobilization of body tissue. Excessive weight loss may prevent sows from coming into heat in a timely manner, prevent sows from being bred, and, even if she is bred, may result in a smaller litter at the next lactation. If a sow loses too much weight and condition during lactation, a potentially very productive sow often needs to be culled before her prime.
What are some steps to maintain feed intake in the summer?
1. Use a Summer Lactation Diet. Even with ideal management techniques, it is difficult to completely eliminate reduced lactation feed intake during the summer. A summer lactation diet with increased nutrient density helps to meet the daily nutrient needs of the sow. For example, assume a sow requires 60 g of standardized ileal digestible (SID) lysine per day and consumes an average of 12 pounds of feed per day during non-summer months. A lactation diet formulated to contain 1.10% SID lysine will meet the daily lysine needs of a sow in this situation.
Now let’s assume average lactation feed intake is reduced to 10 lb./day during summer. A summer lactation diet containing 1.32% SID lysine will still allow the sow to meet her lysine requirements of 60 g/day, even though feed consumption is significantly reduced.
Supplemental fat in the summer lactation diet will increase the energy density of the diet. Even though sows may eat less feed during hot weather, the addition of fat to the diet generally results in an increase in the daily energy intake of the sow. This increase in energy intake helps reduce weight loss by the sow. In addition, other amino acids besides lysine, vitamin, and mineral levels may need to be increased due to the lower feed intake.
2. Keep Feed Fresh. This is important at all times but especially in the summer. Feed is more susceptible to spoilage in hot, humid conditions. The increased susceptibility of feed spoilage in the summer increases the chances that feed consumption will be reduced if feed is not fresh.
3. Feed More Often. One way to keep feed fresh is to feed more often. By feeding more often, you are also feeding smaller meals at each feeding. Sows often consume more feed daily with several smaller meals compared to one or two larger meals. Metabolically, this strategy makes sense, because heat is generated when sows digest the food they eat. A smaller meal lowers the amount of heat generated in the sow’s body at each meal. This lowers the amount of heat the sow needs to dissipate during hot weather.
4. Feed During the Cool Times of the Day. The time of day you feed lactating sows can influence feed intake. Typically, feeding during the cooler parts of the day (early morning, late night) can help improve feed intake. This strategy combined with feeding more often can further improve feed consumption. One challenge with this strategy is adapting worker’s schedules to allow for early morning and late night feedings.
5. Don’t Forget About Water. Water is a critical nutrient that we often take for granted. During hot weather, the sow’s requirement for water is dramatically increased. In addition, there is a direct relationship between water intake and feed intake. If a sow is not consuming an adequate amount of water, her consumption of feed will be reduced.
It is especially important to make sure flow rate through the nipple waterers is adequate. Nipple waterers should deliver a minimum of 1 quart of water per minute and ideally 2 quarts per minute. If flow rates are too low, sows can become very frustrated in their attempts to meet their water needs. Water temperature is also important. Research has shown that a sow will consume nearly twice as much cool water (50°F) as warmer water (80°F). The quality of water should be checked in the spring time to be sure water quality is good going into summer.
Summary Checklist for Lactation Feed Management
1. Use a summer lactation diet.
2. Feed more often.
3. Feed during the cooler parts of the day.
4. Check water quality and water flow rates in all crates. A ½ cup filled in 5 seconds is close to the ideal of 2 quarts/minute.
It is difficult to completely overcome reduced lactation feed intake resulting from hot weather. However, the use of a summer lactation diet and the feeding management steps discussed can help alleviate many of the negative performance results often seen during the summer due to reduced lactation feed intake.
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