Sanket Rajkumar Dhapse, Mokshata Gupta*, Raju Kushwaha
Department of Animal Nutrition, DUVASU, Mathura (U.P.) – 281001
*Corresponding Author email- mokshata.gupta@upvetuniv.edu.in
Chromium (Cr) is a micromineral that plays a crucial role in dairy cattle nutrition, primarily in modifying glucose and lipid metabolisms; insulin sensitivity; improves antioxidant and immune functions. This can lead to improved milk production, better reproductive performance, and enhanced overall health of dairy cows. Feed ingredients commonly available for dairy cows have a low concentration of Cr. To fulfil the requirements of Cr, Cr-containing additives are often added to the diet of cows. Moreover, Cr supplementation may help to mitigate the negative effects of stress on dairy cows, thereby promoting higher milk yields and better efficiency in dairy farming operations.
Chromium and Insulin
Chromium is an essential mineral that plays a role in how insulin helps the body regulate blood sugar levels. Insulin is a hormone that body uses to change sugar, starches, and other food into the energy. Insulin acts as a “key” that unlocks the cell “door,” allowing blood glucose to enter and be used as energy. Chromium improves insulin function and results in efficient clearance of glucose from the bloodstream leading to more cellular energy available for the host.
In growing heifers, supplementation with Cr reduces serum insulin concentrations and insulin:glucose ratios after glucose infusion, indicating increased tissue sensitivity to insulin. Transition dairy cows are generally known for insulin resistance during late gestation and early lactation. Primiparous dairy cows supplemented with Cr exhibited increased insulin sensitivity, while multiparous cows showed no significant change. Multiparous beef cows supplemented with Cr demonstrated lower insulin release without affecting glucose clearance, indicating increased insulin sensitivity.
Chromium vs Feed intake and Milk production
The transition period around calving is crucial for dairy cows’ health and milk production. The Cr supplementation during this period can affect dry matter (DM) intake and milk yield. Studies have shown mixed results regarding the effects of Cr supplementation on prepartum intake, with some indicating increases and others showing no significant change. For instance, supplementation with Cr methionine (CrMet) has shown varying effects on prepartum DM intake depending on the source of grain in the diet. While it increased intake with barley, no significant change was observed with corn as the grain source. Similarly, studies on Cr amino acid chelate (CrAA) supplementation have demonstrated increased milk yield in primiparous cows but not in multiparous ones. Moreover, Cr supplementation during the transition period has shown promising effects on DM intake and milk production in early lactation. Studies have reported higher intake and production during the first few weeks post-calving, especially when CrMet was used. Interestingly, even after discontinuation of Cr supplementation, cows exhibited sustained improvements in intake and production. Variation in responses to chromium (Cr) supplementation in studies may occur due to differences in the chromium content or its bioavailability in feed.
Furthermore, under heat stress conditions, Cr supplementation has shown positive effects on DM intake and milk production in lactating dairy cows, indicating its potential to mitigate the adverse effects of heat stress.
Chromium and Reproduction
Chromium supplementation in dairy cattle has shown promising results in improving reproduction, particularly in primiparous cows. One study demonstrated a reduction in the number of open cows, while another suggested a higher pregnancy rate in cows supplemented with chromium methionine compared to controls, especially in intensively grazed herds. However, the effects seem to vary between primiparous and multiparous cows.
Chromium and Immunity
Dietary chromium supplementation in periparturient dairy cows has been shown to enhance certain aspects of immune response. For instance, cows supplemented with 0.5 mg Cr/kg diet exhibited increased lymphocyte responses to stimulation and maintained their immune function better than unsupplemented cows. Additionally, chromium supplementation improved the antibody response to certain antigens, such as ovalbumin and tetanus toxin, but not to others like human erythrocytes.
Chromium and Stress
High producing dairy cows goes under tremendous pressure and stress during early lactation stage. This causes negative energy balance, increased concentration of non esterified fatty acids (NEFA) and β- hydroxyl butyric acid (BHBA) in blood resulting in ketosis and other metabolic disorders leading to stress. Supplementation of organic chromium in such cases has proven to be beneficial as it reduces blood cortisol concentration. Similarly, its supplementation in transit stressed calves reduces the level of stress.
Chromium Toxicity
Trivalent chromium (Cr3+) is the safe and most stable oxidation state in which chromium is found in living organisms. Hexavalent chromium is mostly of industrial origin and is usually associated with chromium toxicity. In animals chronic chromium toxicosis results in skin contact dermatitis, irritation of respiratory passages, ulceration of the nasal septum and lung cancer, while acute intoxication is rare in cattle.
Conclusion
Chromium has emerged as one of the most significant transition metals that is essential for ruminant health. From mitigating the negative effects of stress and improving insulin sensitivity to positively impacting reproduction and immunity, chromium plays a multifaceted role in dairy nutrition. Studies indicate its potential to improve milk production, reproductive outcomes, and overall immune function, particularly during crucial periods like the transition period and lactation.