How can Amino Acid formulation mitigate heat stress? Because AA formulation improves glucose production and utilization, reduces the NEB associated with heat stress and maintains milk production, reduces oxidative stress, maintains homeostasis in immune responses, reduces intake loss, helps to create low heat increment diets, and helps to restore the intestinal barrier. RP-AA supplementation improves milk production and antioxidant capacity, reduces lymphocyte apoptosis, and enhances dry matter intake and energy-corrected milk under heat-stress periods. Besides that, AA formulation can modulate host immune and inflammatory responses and restore the intestinal barrier after injury could be used in diet during hot conditions.
Stress can be regarded as something that is applied by an external source to an animal that affects the normal physiological behavior of that animal. The intake of dry matter is decreased during stress, which directly affects the output of dairy animals. Heat stress and stress during the transition phase share the same biology and cause more losses to dairy animals among multiple stressors. It's worth mentioning the importance of supplementing chromium and Choline and balancing dietary cation-anion (DCAB) in improving dry matter intake in dairy cows during heat stress.
Apart from hypocalcemia, energy balance is also linked with dry matter intake. Negative nutrient balance is primarily a function of DMI and not milk production early postpartum. Cows have the genetic drive to produce milk at all costs. A higher correlation was found between energy balance and dry matter intake. Cows under heat stress will reduce dry matter intake (DMI) by 20 – 25%, which accounts for ~40 – 50% of the associated milk yield decline. As a result of the decreased DMI, cows under heat stress enter negative energy balance (NEBAL) regardless of their stage of lactation, which can lead to losses in body weight (BW) and body condition score (BCS). Therefore, it can be important to consider nutrition strategies that lower the NEBAL associated with heat stress and allow cows to sustain milk production.
On the other hand, transition cow faces the challenge of heat stress and transition stress. The situation of hypocalcemia in dairy cows also impacts dry matter intake. In a study, when scientists induced SCH, they found that SCH significantly (* P<0.01) reduced rumen contractions and dry matter intake compared to normocalcemic cows.
The impact of SCH and heat stress is much higher than only milk fever and certain metabolic disorders. There are short-term, mid-term, and long-term negative impacts on the profitability of a dairy herd due to SCH. Hence heat stress, hypocalcemia, and energy balance are interrelated and correlated with the cow's dry matter intake.
Learn more in our webinar on heat stress