Total Dairy Nutrition
Volume 1, Number 2
April 1999


Editor:
Dr. Tom Overton
Department of Animal Science
Cornell University
272 Morrison Hall
Phone:  (607) 255-2878
FAX:  (607) 255-1335
Email:  tro2@cornell.edu

 

**RESEARCH FEATURE**

 Recent research conducted at Cornell by Dr. Mike Van Amburgh and graduate students Carolina Diaz and Julie Smith demonstrated that there is substantial opportunity to capture the efficiency by which preruminant calves can deposit lean tissue and grow before weaning. Typical efficiencies of body weight gain by calves in traditional management systems range from .35 to .45 units of body weight per unit of feed intake; however, these researchers measured efficiencies of almost .80 units of body weight per unit of feed intake. These efficiencies are greater than those typically measured in preruminant lambs and nonruminant species such as pigs.

Birth weight, initial weight, slaughter weight, total days on treatment, total dry matter intake, intake as a percent of body weight, and average daily gain of calves fed milk replacer at three levels and slaughtered at 145, 187, and 231 lb. From Van Amburgh, Diaz, and Smith. 1999. Proceedings of Winter Dairy Management Schools (accessible on this site).
 

Treatment 1 (1.1 lb/d)

Treatment 2 (2.1 lb/d)

Treatment 3, (3.1 lb/d)
Number of calves 6 6 6 6 6 6 6 6 6
Birth weight, lb 98 99 105 98 100 98 101 97 97
Actual slaughter weight, lb 144 187 232 150 189 225 150 185 229
Total days on treatment 36 63 94 21 35 59 20 30 45
Total DMI, lb 70.5 131.4 196.1 66.1 127.3 209.4 59.5 110.9 186.2
Target DMI, % of BW

1.5

3

4
ADG, lb/d

1.28

2.23

2.85

Equations have been derived based upon the body composition data in this experiment for energy and protein requirements of calves and are listed below.

Maintenance energy requirement (kcal/d) = 104.2 kcal/BW.75

 Retained energy (RE; Mcal/d) = (liveweight.2955 x 0.544) x (ADG1.262) where ADG is in kilograms (lb/2.2046)

Retained protein (RP)
Birth to 65 kg of body weight RP (g/d) = (96.8 x ADG) + (51.8 x Mcal/kg RE*)

65 to 105 kg of body weight RP (g/d) = (193 x ADG) + (4.8 x Mcal/kg RE*)

*Energy content of the gain (Mcal/kg RE) = ((liveweight.2955 x 0.544) x (ADG1.262))/(ADG * .94)

These equations can be applied to calculate the protein and energy requirements of calves from birth to 105 kg of body weight. These data suggest that the current Dairy NRC equations are underpredicting the tissue protein requirements by 20 to 35%. This concept is different than the dietary crude protein to energy ratio recently proposed by workers at Michigan State and elaborated upon by Dr. Pat Hoffman from the University of Wisconsin at the 1999 Western Dairy Management Conference in Las Vegas. The key point about the crude protein to energy ratio is that it does not account for changes in the composition of the live weight gain (lean versus fat) as an animal matures or the efficiency of use of the absorbed protein. Therefore, a static ratio such as this does not reflect the biology of the growing animal and it is more appropriate to consider net requirements for energy and protein of growing animals that account for changes in body composition as an animal matures. Also, in functioning ruminants the crude protein content of the diet does not necessarily reflect the amount of protein available to meet the tissue (or milk) requirements, which is why most systems have evolved to predict metabolizable protein and energy requirements and supply. Thought question: If the CP to energy ratio was a viable option in most ruminant formulation schemes, why don’t we use it in lactating cows?

T. R. Overton and M. E. Van Amburgh

What are the NRC Phosphorus Requirements for Dairy Cattle?

Environmental considerations indicate that we should reduce overfeeding P in dairy rations. What are the 1989 NRC requirements for P? The table below is for a 1350 lb, 2nd lactation cow producing milk with 3.5% milk fat.

Milk,

P required,

% P required in ration DM

lbs/day

Grams

 DMI Average DMI, - 5% DMI, + 5%

40

52

.31

.33

.30

60

69

.36

.38

.34

80

86

.40

.42

.38

100

103

.43

.45

.41

120

120

.45

.47

.43

How do these numbers compare with your current P formulation levels? Is there an opportunity to decrease ration P levels?

L. E. Chase


Protein for closeup and transition cows

Recent articles, both in popular press (Putnam and Varga. 1997. Feedstuffs 69(40):10.; Garthwaite, Schwab, and Sloan. 1999. Feedstuffs. 71(2):11.) and conference proceedings (Grummer. 1998. Proc. Midwest Dairy Mgt. Conf.) have suggested that diets containing 12% CP or less are adequate for closeup dry cows. Although the authors’ postulation that as DMI of closeup cows increases the percentage of protein required in the diet decreases in order to supply the same amount of protein is true, current requirement systems (NRC; Cornell Net Carbohydrate and Protein System) fail to account for other uses of amino acids within the body (i.e., liver utilization for glucose synthesis and other catabolic processes; Overton. 1998. Proc. Cornell Nutr. Conf. Feed Manuf.). Although data are not currently available to refine these predictions of metabolizable protein requirements, our current requirement systems surely underestimate metabolizable amino acid requirements for transition cows. Ongoing research both at Cornell and at the University of Illinois should provide data to enable us to more accurately determine amino acid requirements for transition cows.

T. R. Overton


Corn Physical Characteristics and Ruminal Starch Degradation

The relationship between endosperm texture and ruminal starch degradation of 14 corn hybrids was reported by workers from INRA in France (Philippeau et. al., J. Anim. Sci., 77:238, 1999). Eight of the hybrids were classified as dent while 6 were termed flint. Ruminal starch degradation was determined using the insitu method. Key results of this study are:

  Dent

Flint
CP, % of DM 10.7 12.0
Starch, % of DM 68.0 67.1
Density, g/cm3 1.29 1.36
Rumen DM degradability, %

55.8

42.3
Rumen Starch degradability, % 61.9 46.2

This study indicates that "softer" grain hybrids (dent) are more completely digested in the rumen than flint type hybrids. This may be an important factor to consider in formulating or evaluating ration carbohydrate levels. Even though total starch content was not different between dent and flint hybrids, ruminal starch digestion was greater with the dent hybrids. This could potentially alter rumen VFA’s, pH and the risk of acidosis.

L. E. Chase



Milk Fat-Protein Inversions

At the recent New England Dairy Feed Conference, Dr. Randy Shaver from the University of Wisconsin indicated that 10-20% of cows in dairy herds may normally have a milk fat-protein inversion. An inversion is when the % milk protein (MP) is higher than the % milk fat (MF). Dr. Shaver used Wisconsin DHI records to examine this relationship. He reported a MP:MF ratio of 1.15 in 1.7 million cow test-day records. This represents about 14.8% of the total records analyzed.

L. E. Chase


What's the Relationship Between True and Total Protein?

True protein will be the protein component used to determine milk price in the revised Federal Order system. New York producers in the past have seen both total and true protein values reported. DHI data is reported as total protein. Some processors and cheese manufacturers have reported true protein information.

Milk total protein is composed of true protein and NPN (nonprotein nitrogen) fractions. The true protein fraction usually represents 94-95% of total protein. An "estimate" of true protein can be obtained by multiplying total protein times 0.95. Thus, a total protein of 3.2% is equal to a true protein of 3.04%. Another option is to subtract 0.16 units from the % total protein to estimate true protein (3.1% - 0.16 = 2.94%). These examples assume that true protein is 95% of total protein.

More details on the new milk pricing formulas will be available in the next few months. In addition, you should receive actual true protein data in the future.

L. E. Chase


1999 Cornell Nutrition Conference

Mark your calendars for October 19, 20, 21, 1999. These are the dates for the 1999 CNC to be held at the Marriott Thruway Hotel in Rochester. Dan Brown and the program committee is finalizing speakers and topics. Breakfast meetings will be sponsored by Zinpro and Alltech. Registration materials will be mailed out in August. Please contact Dee Brothers (dab2@cornell.edu) or Larry Chase (lec7@cornell.edu) if you have any questions. Our FAX number is: 607-255-1335. See you in Rochester!


Dairy Nutrition Courses

The Dairy Professional program will offer both Basic and Advanced Dairy Nutrition courses for feed industry professionals in 1999. Both courses were filled in 1998 and we were pleased with the positive feedback from participants. Dates and locations for 1999 are:

       Basic Dairy Nutrition
August 2 – 6, 1999
Miner Institute, Chazy, NY
       Advanced Dairy Nutrition
August 16-20, 1999
Cornell University

Contact Dee Brothers (dab2@cornell.edu) or Charlie Elrod (cce1@cornell.edu) for a course brochure. The FAX number is 607-255-1335 to request this information.


Email notification

We have had a number of inquiries about this service already. Please email Tom Overton at tro2@cornell.edu to be added to our list of subscribers for notification of new issues.