Every dairy farmer, nutritionist and veterinarian is familiar with the drop in feed intake experienced by almost all cows before calving. Numerous attempts have been made to prevent or reduce the negative effects of that drop in feed intake, but transition cow nutrition and management is still an issue on many farms.
A poor transition from the dry period to milking costs farmers money in terms of higher treatment costs, extra labor, higher veterinary bills and reduces potential milk production, often for the rest of the lactation.
A new concept is being explored at the University of Guelph that is designed to improve transition cow nutrition. There is one important nutrient that does not have a drop in intake associated with calving. In fact, it starts to increase around calving and increases significantly faster than feed intake after milk production starts. That important nutrient is, of course, water, and it is often overlooked as a nutrient. The ingestive behaviors that determine water consumption are based upon a physiological need for every healthy animal to achieve and maintain water balance. Water balance means that water intake (from the consumption of drinking water and moisture present in feeds) equals water output (water present in milk, urine, sweat and exhaled vapor). This explains why water intake increases rapidly in tandem with increased milk production, or else the cow would become dehydrated.
Researchers at Guelph have been investigating water as a way to deliver nutrients to dairy animals in an effort to improve their metabolic status for several years, with positive results. For example, research has shown that flavoring agents added to drinking water of dairy calves resulted in higher calf starter intake and bodyweight gain compared with calves offered only plain water. In another study, glucose supplemented in the water of milking cows improved their nitrogen status, as measured by decreased rumen-fluid ammonia levels and blood urea concentrations.
Dairy scientists don’t yet fully understand all the biological links between water consumption, flavors and taste (as they relate to palatability), feed intake or how the appetite center in the cow’s brain coordinates feeding and drinking behaviors.
The generally accepted nutritional recommendation to increase the energy density of transition cow diets pre-calving has undoubtedly improved transition cow nutrition. However, there is an opportunity to provide supplemental nutrients in drinking water at transition time because water consumption is steady or increasing, in contrast to the typical 30 percent drop in feed intake driven by signals that cause appetite suppression pre-calving. That’s why research was started to take a fresh look at the transition period with the objective of supplementing some energy-dense nutrients in drinking water.
There were no prior data available on fat (oil) or energy-dense nutrient supplementation via drinking water for transition cows. A project was designed that used 70 Holstein cows that were randomly assigned to one of three treatments:
1. No nutrients provided in water (n=20 cows)
2. 20 grams of glycerol (glycerine)/liter of drinking water (n=24 cows)
3. 10 grams of soybean oil/liter of drinking water (n=26 cows)
Treatments were applied from seven days before calving to seven days after calving. Ninety cows were planned to be used in the study, but 20 calved before treatments were started and they were omitted from the statistical analysis of the study.
The total energy provided to the cows by the glycerol and soybean oil was designed to be the same based on predicted water consumption from previous studies. Soybean oil was chosen because its nutritional effects have been well characterized in many experiments and glycerine is well-suited to water supplementation and is anticipated to be in greater supply as a feed ingredient as a byproduct of the biodiesel industry.
The results of supplementing these energy-dense feeds in water were promising in many respects. Water intake from the three treatments is shown in Figure 1 and it shows the steady consumption of water pre-calving and the rapid increase post-calving. Overall, there was no difference in net energy intake or net energy balance between the three treatments, but cows on the glycerol (10.9 kg/d) and soybean oil (11.3 kg/d) had lower dry matter intake than the control cows (12.4 kg/d).
The cows on the supplemented water treatments, therefore, consumed sufficient energy from either glycerine or soybean oil to offset the modest reduction in energy obtained from lower feed intake. Other researchers who have orally drenched cows with glycerol post-partum have reported reduced feed intake but no change in blood glucose and non-esterified fatty acid (NEFA) concentrations.
No differences, either pre- or post-calving, were detected for blood serum concentrations of NEFA or glucose between energy supplemented water treatments and control. However, reductions in beta-hydroxybutrate concentrations were measured post-calving in the oil and glycerine treatment groups compared with control cows as shown in Figure 2, which could have some benefit for reducing sub-clinical ketosis.
The potential to implement a plumbing system capable of supplementing desired nutrients into the water for maternity or hospital pens on dairy farms exists. All of the equipment that is necessary to build a system is readily available including the electronic medicator delivery unit necessary to incorporate the supplemental liquids into a water bowl or trough. The costs for a typical installation including electronic metering system and retrofitting are approximately $1,500 to $2,000 for a barn’s maternity pens.
The benefits to a “self-drenching system” will be optimized when the combination of supplemental nutrients in water and dry matter intake maximizes net energy intake and reduces the negative energy balance of early lactation. Additional research will investigate other potential energy sources and optimize their dosing rates in water to make this concept a reality for those cows experiencing reduced feed intake that require additional energy supply without subjecting them to the handling stress and added labor associated with oral drenching routines. PD
References omitted but are available upon request at editor@progressivedairy.com
Dr. Tom Wright is the Extension dairy nutritionist with the Ontario Ministry of Agriculture, Food and Rural Affairs in Canada. Dr. Vern Osborne is a professor in the Department of Animal and Poultry Science at the University of Guelph in Canada.
Vern Osborne
Professor University of Guelph
