Despite many efforts to control and treat neonatal calf diarrhea (NCD), it remains the primary cause of calf mortality in dairy herds worldwide. The objective of this article was to develop and discuss an empirical therapeutic protocol to save newborn calves with severe diarrhea. The pathophysiology of diarrhea has been well described previously. However, there is a significant gap between scientific findings and practical implementations. Reducing the number of calves with failure of passive transfer, regular sanitation of the calf environment, and optimal dry cow nutrition and management are fundamental measures in controlling diarrhea in commercial settings. As such, optimizing colostrum feeding management and improving ambiance hygiene are among the most important management practices to prevent calf diarrhea. Nonetheless, the occurrence of NCD would be unavoidable due to its multifactorial nature and pathophysiology. According to the degree of dehydration and general appearance of ill calves (e.g., degree of sunken eye and loss of suck reflex), NCD can be classified into mild to severe cases. Early diagnosis and treatment of both mild and severe cases could reduce pathogens shedding into the calf environment. Notably, diarrhea treatment needs profound scientific farm education and mentoring regarding the physiology of NCD. Since a variety of organisms, such as bacteria, viruses, and protozoa, may be responsible for NCD, it is evident that reliable diagnosis requires optimal sampling and laboratory analysis. However, waiting for laboratory results may waste the golden time of treatment. Therefore, rapid and decisive treatment would be mandatory, especially in severely infected calves or sepsis cases. Accordingly, an effective aggressive treatment protocol was developed and discussed in this article as the last chance to keep diarrheic calves alive.

Diarrhea is the most perturbing disease in dairy and beef industries worldwide, leading to significant rates of morbidity and mortality as well as economic losses. The objective of this review article was to delineate the pathophysiology and practical biology of colisepticemia in neonatal calves. Preventive and therapeutic protocols were also presented and discussed from a new integrative perspective. Notably, the situation can be the most deleterious in case diarrhea turns into septicemia. Under such circumstances, the mortality rate may be remarkably high and hard to control. Escherichia coli (E. coli) is an invasive and opportunistic bacteria causing severe diarrhea (colibacillosis) and colisepticemia in newborn calves. Colisepticemia is commonly prevalent in 2-5 days old calves, and colostral immunity is considered the first defensive line against E. coli infection. In addition to colostrum feeding quality and management, other management factors, such as dry cow nutrition and welfare, newborn calf welfare and nutrition, housing system, sanitation protocols, as well as early identification and treatment of sick calves, are important in preventing colisepticemia. In conclusion, understanding the mechanism of action and transmission routes of pathogenic E. coli will provide scientific and practical insight to plan preventive and therapeutic protocols decisively and successfully.

The transition phase is thought to be the most critical period in high-producing dairy cows’ productive cycle. Maternal stresses during the peripartum period affect both dam and newborn calf health. The objective of this review article was to describe the role of prepartal metabolic and environmental stressors on postpartum-related disorders in both cows and newborn calves. The transition phase (21 d before to 21 d after calving) is considered the most critical period in dairy cattle life. Decreased dry matter intake coincides with increased nutrient demands due to the onset of lactation. It can lead to negative energy balance and tremendous metabolic challenges for high-producing dairy cows. During this time, insulin concentrations and peripheral tissue sensitivity decrease, leading to fat mobilization from adipose tissue. Such incidences would increase levels of non-esterified fatty acids and beta-hydroxybutyric acid in plasma. The success in the transition from the dry to lactating phase depends on how the cow could deal with such challenges. Failure to handle such metabolic alterations may predispose cattle to costly metabolic disorders such as ketosis, fatty liver, retained placenta, displacement abomasum, and infectious diseases, including metritis and mastitis in the postpartum period. The energy content of dairy cow diets in the dry-off (40 days before calving) or close-up (21 days before calving) periods may influence cow physiology and health in the peripartum period. The role of a transition period diet on cow health and productivity in the early or overall lactation period has been frequently investigated. However, the role of stressors such as nutritional deficiencies, heat stress, stocking density, and grouping in the late gestation period on the health and performance of cows and calves are much less addressed. Therefore, the present review delineates and reviews updates on the role of maternal stresses during the peripartum period on dam as well as newborn calf physiology and behavior.

Forage nutrition for pre-weaning calves hosts numerous practical questions and on-farm challenges. The present review article aimed to update and address the biological consequences of forage provision to pre-weaned dairy calves. Health, nutrient intake (milk plus solid feed), and rumen development are the most important factors related to calf growth in pre- and post-weaning periods. A growing body of evidence suggests that the health and growth performance of dairy calves in the pre-weaning period are associated with their later performance as dairy cows. It seems that starter feeding strategies, including grain type, processing method, feed texture, and forage inclusion during the critical pre-weaning period may have profound effects on rumen function and calf performance. It is well understood that grain fermentation by-products are essential for increased growth and absorptive capacity of the rumen papillae. Forage provision as a part of a starter diet has been a topic of recent research. The rumen pH is the main factor altering the fate of fermentation and eventually animal health. In the pre-weaned calf, two major hypotheses exist regarding forage feeding. The first hypothesis describes that the rumen is not completely developed in pre-weaned calves and forage provision during this period might increase gut fill, and hence, decrease starter intake. It is believed that depressed starter intake may limit energy intake and finally suppress calf growth rate. The second hypothesis indicates that the rumen pH may decline as calves age and starter intake increases. Accordingly, forage inclusion in calf starter diets could prevent further rumen pH decline and subsequent negative consequences while improving starter intake and calf growth. Research data regarding these hypotheses are controversial. Many factors, such as milk feeding method, grain, forage type, and experimental conditions could affect calf responses to dietary forage. The current review focused on the biological consequence of forage provision to young calves to provide a practical framework for better use of forages in pre-weaned calves feeding programs. Keywords: Forage, Growth, Pre-weaned calf, Rumen development