Regulation of dry matter intake (DMI) is a complex integrated process to ensure an adequate supply of energy to meet important nutrient requirements controlled by 1) Physical limitations or gut fill; 2) Metabolic; and 3) Management, facilities and environment.
Daily intake relies on the feeding behavior of dairy cows, which is determined by: meal frequency or meals per day; meal length (min per meal); feeding rate (pounds consumed per min); and meal size (pounds per meal; Table 1).
Poor consistency in feeding management (e.g., linear feed bunk space per cow, TMR delivery), facilities (e.g., bedding surface, number of stalls relative to cows; comingling younger and older cows) and environment (e.g., high THI) can interfere negatively with feeding behavior and substantially reduce daily DMI in both transition and lactating cows.
Understanding feeding behavior (Table 1) and the factors influencing DMI are critical for successful ration formulation, feed bunk and herd management. In turn, this would determine optimum DMI during the transition period to optimize health status, resumption of estrus cyclicity, reproduction, and milk yield.
When feeding space at the bunk is limited (<50 cm or <20 inches per cow), cows become more aggressive to gain access to feed and respond to overcrowding by increasing feeding rate (eat more feed per meal with the risk of negatively affecting rumen health).
First-lactation cows, however, have limited capacity to increase their feeding rate. Although lying time varies according to the stage of lactation and age, lactating dairy cows have a strong behavioral need to rest (lying down) for approximately 12 hours per day. It has been shown that dairy cows choose resting over eating time when the opportunity to perform these behaviors is limited.
Cows with elevated core body temperature resulting from increased THI (above 68) spend more time standing than lying compared with thermoneutral cows, prefer eating during the cooler nighttime, and had reduced DMI.
Practical implications
Improving cow comfort at the farm level by removing barriers affecting intake is perhaps the single greatest opportunity to promote feeding behavior and optimize DMI.
a) What is cow comfort? It is an environment with minimal stress as defined by the five principles of animal welfare: free access to feed and water, thermal comfort, able to express their natural behavior [e.g., eating, resting, walking], positive animal-people interactions and free of disease and pain. Cow comfort is largely determined by people (management), facilities, and environment (e.g., heat stress). People can overcome facility limitations, but great facility design cannot replace poor management.
b) For optimum DMI, offer 30 inches of linear feed bunk space per cow with feed available within reach of cows for at least 22 hours per day. Also provide 4 inches of linear water space per cow with a at least 10 gallons of water flow per minute.
c) Under farm conditions, feeding twice daily compared with once daily was associated with an average increase of 3.1 pounds of DMI, 4.4 pounds of milk yield, and less sorting against long ration particles (>19 mm or >0.7 inches). In controlled experimental conditions when TMR was available 22 out of 24 hours per day, feeding twice or thrice daily had minimal effect on DMI but cows sorted less with reduced risk for sub-acute rumen acidosis compared with feeding once daily. Pushing up TMR every 2 hours interval rather than every 4 or more hours, increased eating time by 20 minutes per day (an increment of approximately 1.5 pounds per day of DMI per cow. Goal: Feed transition cows twice per day with push-ups every 1-hour interval.
d) Update daily pen counts in management and feeding software (number of cows per pen) to ensure proper delivery of TMR and DMI.
e) For transition cows, formulate rations with 5% refusal. When calving rate is above average for the herd and transition pens are over-crowded relative to linear feed bunk (<50 cm or <20 inches per cow) and bedding space (e.g., >100% number of cows relative to number of stalls), offer more TMR at the bunk by formulating ration with 8% feed refusal.
f) Comingling first-lactation cows with multiparous cows alters feeding behavior and reduces DMI for primiparous cows. Mature cows are more aggressive when eating at the feed bunk than younger cows. Thus, when comingling first-lactation cows with multiparous cows in transition pens, offer more TMR at the bunk (5% feed refusal). To optimize DIM, transition cows should be grouped by parity (primiparous separated from multiparous) and lactating cows by similar stages of lactation.
g) Regularly check the heat abatement system (e.g., fans, sprinklers, shade). There is a strong negative correlation (r = -0.82) between THI and DMI, in which DMI can be reduced by 1 lb per day for every 1-unit increment in THI above the THI threshold of 68 (cows with high milk yield had lowest DMI).
h) Have a system in place to identify inconsistencies of DMI over time by assessing cows, nutrition, management and environment. For instance, the effect of daily THI, accuracy of daily feeding schedule relative to actual TMR delivery, loading accuracy of ingredients (% error), stocking rate relative to linear feed bunk and resting space and time that feed bunk is empty relative to feed refusal.
i) For automatic or robotic milking systems, in addition to the factors listed above, the most important factors to optimize DMI are: match type and amount of concentrate to barn design; and feed push-ups 12 times per day, and provide best possible digestibility of diet in the partial mixed ration.
Takeaways
Perhaps the best or most successful dairy farms (in terms of reproductive performance, milk quality, and cow longevity) have achieved consistent management over time by implementing a simple but effective transition program to promote feeding behavior and DMI; thus, performance (milk and reproduction) and overall animal welfare.
An ounce of prevention is worth a pound of cure! Please have this discussion with your veterinarian and nutritionist. These little details make the difference at the end of the day.
