Ration Balancing

Testing forages and balancing rations are the foundation upon which nutritionists build sound, nutritionally-complete feeding programs. As we learn more about rumen fermentation, use of nutrients within the mammary gland, liver, and other tissues, and the interactions between the rumen environment and cow’s metabolism, specifications for nutrients used when formulating rations have changed and become more sophisticated. To take advantage of these advances, more complicated ration balancing models are utilized which often require more nutrient composition data to be entered for each feedstuff. Often we use “book values” which may or may not describe the nutrient composition of the feedstuff actually being fed. These inadequacies and gaps in our knowledge of rumen fermentation and nutrient metabolism can lead to performance which may not meet expectations.

From a practical standpoint when rations do not perform as well as expected, the most common problem is not the ration formulation, but rather, the interpretation and feeding of the ration and the amount and composition of the ration actually consumed by the cows. Thus, highlighting the statement describing the four different rations which are fed to cows or heifers (Table 1). When troubleshooting performance problems, these areas often offer at least a partial explanation. Table 2 illustrates the various areas that should be evaluated when formulated rations are not performing as expected.

Table 1. Ration fed to the Dairy Herd
1.) Ration formulated by a nutritionoist
2.) Ration fed to the cows
3.) Ration consumed by the cows
4.) Ration deigested by rumen bacteria and the cow

Table 2. Possible reasons why formulated rations may not be work as expected.
Inconsistencies in rations formulated by nutritionist
1.Ration formulation does not use foratges currently being fed (i.e. type of hay and/or silage, pasture incorporated but not utilized as forage source by cows)
2.Ration being fed does not utilize analysis of forages or feeds currently being fed
3.Ration does not reflect actual dry matter intake for the herd
4.Ration formulation does not account for inclusion or variability of by-products being fed
5.Dry matter changes of forages stored in silage bags and bunkers.
Inconsistencies in ration actually fed
1.Ration offered to cows does not reflect amounts on formulated ration
a.Formulated ration does not reflect types and amounts of forages and other feeds currently available
b.

Formulated ration can not be fed through the farmer’s feeding system (i.e. Amount and type of hay included in TMR’s, forages or concentrate to be fed)

c.Formulated ration does not reflect farmer’s feeding goals (i.e. types and amount of forages to feed)
2.Consistency of ration being fed especially TMR’s
a.Amount fed does not reflect changes in dry matter of forages and other wet feeds
b.Dry matter proportions of each feed do not remain relatively constant from feeding to feeding (i.e. as fed amounts of forages and concentrates (or grain) change to adjust for varying feed intakes)
c.Transition between different forages (i.e. type of forages and silos)
d.Too small quantities of ingredients being added that they can not be weighed accurately and/or be adequately mixed within the diet (i.e. mineral ingredient (not mixed with an additional carrier) being added to a TMR)
3.Feed bunk management
a.Free choice versus limit feeding
b.Provide adequate bunk space
c.Access to feed 20 hours per day – feed pushed up
d.Feeding surface (height and smoothness) and location
4.Communication between the nutritionist, farmer and the person (s) actually feeding the cows - cows being fed correctly according to balanced ration
Inconsistencies in rations actually consumed by dairy cows
1.Sorting of offered TMR or silage by cows
2.Selective consumption of forages especially long stem hay - i.e. location relative to traffic patterns, quality of hay offered, and quantity consumed relative to feed space)
3.Inability to consume feeds within the constraints of the feeding system
 

Resolving Nutritional Problems

Often the formulated ration (and the nutritionist who formulated the ration) gets blamed when cows do not milk as well as expected or health issues arise in the herd. The formulated ration can be the problem but other management-related factors can contribute to the problem. Often, changes in management practices are needed to resolve the problem in addition to formulation changes or refinements. Most nutritional problems are often a combination of several factors that have changed which result in a decrease in milk production, growth or health problems. Some of the areas that should be investigated to resolve some of the common problems seen in dairy herds can be seen in the article entitled Areas to Evaluate when Troubleshooting and Resolving Nutritional Problems in Dairy Herds.

Trace Mineral Nutrition

Proper mineral and vitamin nutrition impacts milk production, growth, reproductive performance, and the health of cattle. From a health standpoint, proper mineral and vitamin nutrition can help prevent several common metabolic disorders, such as retained placenta and clinical and subclinical milk fever, and improve the immunity of cattle to fight off diseases, such as mastitis. Also, proper mineral and vitamin nutrition can help improve immunity from vaccines administered to prevent various diseases.

Minerals and vitamins need to be provided in adequate amounts in forms which are readily absorbed (bioavailable). The amount of minerals provided by forages, concentrates or grains, mineral sources, and water need to be taken into account when evaluating the mineral adequacy of diets for growing heifers and lactating and dry cows. Forages and concentrate mixes should be analyzed via wet chemistry methods to determine their mineral content and the results used to assess whether the proper amount of each mineral is provided. Often we forget that cattle need a certain amount of each nutrient, not concentrations of a nutrient. The mineral content of water needs to be taken into account when evaluating the adequacy or excesses of a trace mineral and vitamin program.


Figure 1. Mineral interactions

Interactions with other minerals

Various minerals have been shown to interfere with the absorption or metabolism of other trace minerals (Figure 1). Table 4 lists some of the common mineral interactions which can decrease the effective absorption of copper and selenium and result in health-related problems in dairy and beef herds. Higher concentrations of iron, sulfur, zinc or molybdenum can be found in not only forages (Table 5) but also water sources and mineral sources, such as dicalcium phosphate (Table 5). For example, some sources of dicalcium phosphate contain higher concentrations of iron than other sources. To counter these interactions often organic sources of copper or selenium are added to the diet.

Table 4. Common Mineral Interactions
Fe↔Cu
S↔CU
Zn↔Cu

Table 5. Selected mineral concentration in alfalfa haylage and dicalcium phosphate.

 

Sample

1

2

3

4

Alfalfa Haylage1, Iron (ppm)

Crop Year 1

461

1,370

664

1,350

Crop Year 2

1,320

761

2,230

Crop Year 3

181

347

380

678

Dicalcium Phosphate2

Iron (ppm)

2,632

15,093

12,157

5,026

Magnesium (%)

0.32

0.43

1.73

0.98

Sulfur (%)

0.47

0.99

0.86

0.72

1 Samples collected at University of Kentucky Coldstream Dairy Research Facility

2 Adapted from Wendlandt, Ron. 1997. Field Observations of Mineral Supplements. Proceeding for Kentucky Nutrition Workshop. Pg. 51-53

 

Implementing a Close-up Dry Cow Program

Properly-implemented close-up dry cow programs have been shown to improve production (+/- 2000 lbs milk) and health of cows after calving. Several additives, such as anionic salts and other B vitamins (i.e., ruminally protected choline), have been shown to minimize health problems when added to diets 3 weeks prior to calving. Implementing close-up dry cow programs with our smaller herd sizes has presented some challenges and problems. These difficulties may include (1) providing facilities that provide adequate cow comfort, bunk space, and hygiene for both groups of dry cows; (2) mixing and storing another grain mix specially formulated for the forages being fed which can be fed out within a reasonable time frame; and (3) small numbers of cows in this group makes mixing small batches of TMR, especially those incorporating long hay, a challenge. With the research showing that we may be able to shorten dry periods from the classic 60-days, we may again be able to house dry cows in a single group fed a common diet which will help eliminate some of the reluctance by farmers to implement these management practices.

Communication...

Establishing true communication lines between you, the farmer’s other consultants, the farmer, and his/her staff are critical when designing and implementing feeding programs that work. Communication needs to flow to and from all parties which are involved in the feeding program. Often the greatest misunderstandings could have been avoided or quickly corrected if communication lines have been established and all parties truly communicate, with one another. To accomplish these objectives, both sides need to listen to each others’ needs and concerns raised.


Author: Donna Amaral-Phillips

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