6. Body Condition

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There are multiple ways to measure the effects of rbST on body condition. The data base includes values for each of the following parameters.

• BCS through tx period - this represents the average difference between body condition scores (measured on a scale of 1 to 5) when assessed at regular intervals throughout the treatment period.
  • BCS > 200 - this represents the difference between treated and control cows in final body condition score (measured on a scale of 1 to 5) for studies in which the treatment period was over 200 days.
  • BCS < 200 - this represents the difference between treated and control cows in their final body condition score following a treatment period of less than 200 days.
• Body Weight - the difference in body weight between treated and control cows at the end of the treatment period.
• Change in BCS - the relative difference between treated and control cows in the change in body condition score over the treatment period.
• Daily weight change - the difference between treated and control cows in their daily average weight gain over the treatment period.

Although all these parameter were included in the database, BCS > 200 was most commonly extracted from studies reviewed and was the subject of a series of meta- analyses.

6.1 BCS > 200

6.1.1 Meta-Analysis

Three meta-analyses were carried out to evaluate the effects of rbST on body condition.

• Effect of rbST on body condition score based on studies using all companies' product.
• Effect of rbST on body condition score based on studies using Monsanto's product.
• Effect of rbST on body condition score in the "carry-over" period.

Although body condition score data (BCS > 200) were reported in many studies, many studies did not report standard errors of the estimates and consequently these results could not be included in the meta-analyses.

. meta val se , pr gr(f) id(std_lbl) cl xline(0) ltrunc(-.5) rtrunc(.3) xlabel (-.5, -.3, -.1, 0, .1, .3) b2("BCS > 200 days - All Companies")

Meta-analysis

Effect of rbST on 3.5% FCM

Method	Pooled Est	95% CI Lower	95% CI Upper	Asymptotic z_value	Asymptotic p_value	No. of studies
Fixed	-0.188	-0.258	-0.117	-5.219	0.000	4
Random	-0.218	-0.344	-0.092	-3.392	0.001

Test for heterogeneity: Q= 8.718 on 3 degrees of freedom (p= 0.033) Moment-based estimate of between studies variance = 0.011

Effect of rbST on 3.5% FCM

Study	Weights Fixed	Weights Random	Study Est	95% CI Lower	95% CI Upper
1 Mm1	118.15	52.51	-0.25	-0.43	-0.07
1 Mp1	229.57	66.95	-0.17	-0.30	-0.04
168 Cm1	106.28	50.03	-0.42	-0.61	-0.23
168 Cp1	318.88	72.90	-0.10	-0.21	0.01

BCS > 200 days - All Companies

. meta val se , pr gr(f) id(std_lbl) cl xline(0) ltrunc(-.5) rtrunc(.3) xlabel(-.5, -.3, -.1, 0, .1, .3) b2 ("BCS > 200 days - Monsanto")

Meta-analysis

Effect of rbST on 3.5% FCM

Method	Pooled Est	95% CI Lower	95% CI Upper	Asymptotic z_value	Asymptotic p_value	No. of studies
Fixed	-0.197	-0.302	-0.092	-3.677	0.000	2
Random	-0.197	-0.302	-0.092	-3.677	0.000

Test for heterogeneity: Q= 0.499 on 1 degrees of freedom (p= 0.480) Moment-based estimate of between studies variance = 0.000

Effect of rbST on 3.5% FCM

Study	Weights Fixed	Weights Random	Study Est	95% CI Lower	95% CI Upper
1 Mm1	118.15	118.15	-0.25	-0.43	-0.07
1 Mp1	229.57	229.57	-0.17	-0.30	-0.04

BCS > 200 days - Monsanto

. meta val se , pr gr(f) id(stdy_lbl) cl xline(0) ltrunc(-.5) rtrunc(.3) xlabel( -.5, -.3, -.1, 0, .1, .3) b2("BCS > 200 days - Carry-over Period")

Meta-analysis

Effect of rbST on 3.5% FCM

Method	Pooled Est	95% CI Lower	95% CI Upper	Asymptotic z_value	Asymptotic p_value	No. of studies
Fixed	-0.194	-0.319	-0.069	-3.043	0.000	3
Random	-0.194	-0.319	-0.069	-3.043	0.000

Test for heterogeneity: Q= 0.082 on 2 degrees of freedom (p= 0.960) Moment-based estimate of between studies variance = 0.000

Effect of rbST on 3.5% FCM

Study	Weights Fixed	Weights Random	Study Est	95% CI Lower	95% CI Upper
5421 Mm1	52.51	52.51	-0.20	-0.47	0.07
5421 Mp1	25.25	25.25	-0.14	-0.53	0.25
5422 Mm1	168.66	168.66	-0.20	-0.35	-0.05

BCS > 200 - Carry-over Period

6.1.2 Comments and Conclusions

The overall estimate of the effect of rbST on body condition score was a reduction of approximately 0.2 units (on a scale of 1 to 5) at the end of the treatment period. However, only 2 studies (18,19) had reported adequate data (i.e. point estimates and standard errors) to allow them to be included in the meta-analysis. Other studies which reported point estimates of body condition scores at the end of the treatment period (i.e. BCS > 200) reported an average reduction of 0.15 units (based on a simple arithmetic average).

There was evidence that this reduction in body condition carried over into the early lactation period of the subsequent lactation period. Although this was recorded from relatively few studies, the meta - analysis of 3 studies which did report this parameter found a significant reduction in body condition of approximately 0.2 units in the early lactation period.

6.2 Other Estimates of Body Condition

Two studies (10,20) involving 4 groups of cows reported body conditions scores throughout the treatment period. On average they reported scores approximately 0.4 units lower in treated cows than in control cows. Statistical significance was only assessed in the former study and in that study the reductions were significant.

Of the 5 studies which reported body condition scores at the end of a treatment period which had been less than 200 days in length, 4 of them reported a reduction in body condition.

Body weights at the end of a treatment period were recorded from 5 groups of cows with lower body weights in treated cows being reported in 3 groups. However, body weight is influenced by the amount of feed in the digestive tract so it may not be as reliable an estimate of body condition.

Change in body condition score values were reported from 4 groups of cows on 2 studies with control cows gaining less body condition than treated cows in all groups. Two studies reported change in body weight as daily weight changes and once again, treated cows gained less weight than control cows.

6.3 Comments and Conclusions - Body Condition

The effect of rbST on body condition was reported in many different ways across many studies. Overall though, it was evident that treatment with rbST results in lower body condition at the end of the treatment period. It was also evident that this reduction in body condition persists into the early period of the subsequent lactation.

The Panel concluded that treatment with rbST did reduce body condition scores in cows in the research studies evaluated.

The Panel did not feel any additional information was required to evaluate the effect of rbST in the research herds. The Panel noted that it was unfortunate that body condition scores had not been recorded in the PAMP study as this would have provided a better estimate of the effect of rbST on body condition in a variety of commercial herds.

6.4 Ability to Control/Eliminate Detrimental Effects

The Panel noted that most of the studies were carried out in institutional research herds and were subjected to very good nutritional management. Despite the increase in dry matter intake associated with treatment and the high level of nutritional management, treated cows entered the subsequent lactation in a lower state of body condition than control cows.

Programs for balancing dairy cow rations are constantly being improved. However, achieving the ideal of a completely balanced ration requires excellence in many areas (eg. forage production, ration balancing, feeding management etc.) and that excellence is rarely achieved in all of these areas together. Consequently, the Panel concluded that using the nutritional management programs that are common on the majority of commercial dairy herds, it would be a challenge to maintain body condition in cows treated with rbST.