Livestock Production Science 65 2000 91–105 www.elsevier.com locate livprodsci
Prediction of energy balance in a high yielding dairy herd in early lactation: model development and precision
a , b
a b
a
C. Heuer , W.M. Van Straalen , Y.H. Schukken , A. Dirkzwager , J.P.T.M. Noordhuizen
a
Utrecht University , Department of Farm Animal Health, Yalelaan 7, 3584 CL Utrecht, The Netherlands
b
CLO Institute of Animal Nutrition , De Schothorst, Meerkotenweg 26, P.O. Box 533, 8200 AM Lelystad, The Netherlands
Received 5 May 1999; received in revised form 18 October 1999; accepted 9 November 1999
Abstract
This study was conducted to 1 predict herd mean EB, and 2 investigate whether herd size affects the precision of prediction. In order to achieve the first goal, it was studied to what extent milk test day information, body condition scores,
and blood and milk ketones can estimate energy balance at cow level. EB was calculated in 72 Holstein–Freisian cows of one research herd 10,500 kg milk per 305-day lactation during lactation weeks 2–12. A repeated measures model was used
for multiple regression of predictors on energy balance. In addition to a base model including lactation week, parity and milk yield, the fat–protein-ratio, milk fat and milk protein concentrations explained substantially more variability in EB
than did milk lactose concentration and body condition scores, or tests for ketone bodies. A simulation of random selections of milk test day and animal subsets showed that sufficiently precise prediction of energy balance would require either herds
larger than 150 cows or pooling of the results of subsequent test days. It was concluded that milk test day information without ketone levels or body condition scores is sufficient to estimate herd mean energy balance, but that herd size limits
the precision of prediction. Model validation in other herds and rations would be the next phase of this research.
2000
Elsevier Science B.V. All rights reserved.
Keywords : Dairy cattle; Herd mean energy balance; Test day information; Metabolic parameters; Body condition scoring; Precision of
prediction
1. Introduction 1991 and may result in increased time to first
ovulation and failure to conceive Senatore et al., Maximal energy intake and utilisation in the early
1996. The real intake of energy and other nutrients lactation period is crucial for optimal health and
often deviates from planned rations Simensen et al., production of high yielding dairy cows Goff and
1990 because dry matter intake depends not only on Horst, 1997. Insufficient energy intake postpartum
the ration but also on changing environmental factors increases the risk of primary ketosis Lean et al.,
such as climate, roughage quality, animal density, housing conditions or feeding practices. Monitoring
the nutrient intake of a high yielding dairy herd is
Corresponding author. Tel.: 131-30-253-1155; fax: 131-30-
therefore important for the management of nutrition.
252-1887. E-mail address
: c.heuervet.uu.nl C. Heuer
The difference between energy intake and energy
0301-6226 00 – see front matter
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. Heuer et al. Livestock Production Science 65 2000 91 –105
requirement is the energy balance EB. Possible 2.1. Cows, feeding, measurements, and
indicators of EB are body condition scores BCS calculations
and concentration of glucose, free fatty acids, and ketone bodies in blood or milk Gravert et al., 1986;
At a dairy research farm Institute of Animal Magdus et al., 1988; Gustafsson and Emanuelson,
Nutrition, De Schothorst, Lelystad, The Nether- 1996; Dirksen et al., 1997. However, the correla-
lands, 72 Holstein–Freisian cows of parities 1–11 tions between EB and, respectively, blood glucose,
were observed for a total period of 21 weeks acetoacetate and beta-hydroxy-butyrate BHB ap-
beginning at calving. The herd average 305-day milk pear to be low Garnsworthy, 1988, and an earlier
production was | 10,500
kg. The cows were evaluation of our field data showed that high or low
synchronised for the trial by timed insemination so BCS of fresh cows or BCS-loss postpartum were
that calving occurred within a short period Sept. unrelated to clinical ketosis Heuer et al., 1999.
10–Nov. 26, 1996. This study on postpartum EB Because milk recording is regularly done in most
was part of a feeding trial in which the cows were dairy herds, there is a growing interest to evaluate
randomly allocated to six trial diets designed to milk yield, fat and protein concentrations as in-
compensate lack of roughage quality with four dicators of EB. A ratio of percent milk fat over milk
different types of concentrate. The ration consisted protein . 1.5 of the first test day increased the risk
of a mixed grass–maize silage at a ratio of 3:1 at dry of metabolic diseases Geishauser et al., 1997; Heuer
matter weight basis, and the four different trial et al., 1999. The correlation between the fat–
concentrates fed at increasing amounts from 5.5 kg protein-ratio and EB among cows was in the range of
day 1 1 2 to 14.0 kg after day 26. The difference 2
0.36 to 2 0.74, and the fat–protein-ratio explained in roughage quality between the control and the five
19–21 of the variance of EB in a multifactorial experimental diets turned out to be small. It only
analysis of various feeding experiments Grieve et affected the net energy content and amounted to 0.20
al., 1986; Gravert, 1991. MJ NEL kg DM. All experimental rations were
In addition to the fat–protein-ratio, EB is associ- formulated to meet requirements Van Es, 1978;
ated with lactation stage, milk yield, age, BCS, and Tamminga et al., 1994. The ration composition,
metabolic parameters, such as BHB Grieve et al., DMI and balances of energy, protein and rumen
1986; Garnsworthy, 1988; Gravert, 1991. Hence, nitrogen are shown in Table 1.
more valid estimates of EB may be obtained if The trial diets started in lactation week 6 after a
effects of age, lactation stage, milk yield, BCS, and pre-trial period of 5 weeks during which good
BHB would be considered in the analysis of milk test quality roughage and a standard concentrate were fed
day information. to all cows. The transition to moderate quality
The ultimate objective of this study was to predict roughage occurred abruptly within 1 day, the shift to
the mean EB of cows in a dairy herd during the first the different types of concentrate gradually within 1
3 months of lactation and to evaluate the effect of week week 6–7. Roughage was mixed and fed
herd size on the precision of prediction. individually ad libitum twice a day 07:00 h, 15:00
h facilitated by transponder operated feed-troughs for individual cows. Leftovers were weighed and
2. Materials and methods deducted from total amounts fed. They were negli-
