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 Table 4. Summary of MGA (melengestrol...
 Table 5. Effects of MGA (melengestrol...
 Table 6. Effects of MGA (melengestrol...
 Table 7. Estrus data for the MGA...
 Table 8. Effects of MGA (melengestrol...
 Table 9. Summary of combined growing...














Group Title: WFES mimeo report ;, 68-4
Title: The value of melengestrol acetate (MGA) in the ration of beef heifers
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00053531/00001
 Material Information
Title: The value of melengestrol acetate (MGA) in the ration of beef heifers
Series Title: WFES mimeo report
Physical Description: 2, 9 leaves : ; 28 cm.
Language: English
Creator: Bertrand, J. E ( Joseph Ezel ), 1924-
West Florida Experiment Station
Publisher: West Florida Experiment Station
Place of Publication: Jay Fla
Publication Date: [1968]
 Subjects
Subject: Beef cattle -- Feeding and feeds -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: J.E. Bertrand.
General Note: Caption title.
General Note: "May, 1968."
Funding: Mimeo report (West Florida Experiment Station) ;
 Record Information
Bibliographic ID: UF00053531
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 62311143

Table of Contents
    Main
        Page 1
        Page 2
    Table 1. Summary of MGA (melengestrol acetate) beef heifer finishing trials - MGA versus no drug
        Page 3
    Table 2. Summary of MGA (melengestrol acetate) beef heifer finishing trials - MGA versus oral DES (Diethylstilbestrol)
        Page 4
    Table 3. Summary of MGA (melengestrol acetate) beef heifer finishing trials - MGA versus implanted DES (Diethylstilbestrol)
        Page 5
    Table 4. Summary of MGA (melengestrol acetate) beef heifer finishing trials - MGA versus Synovex-H implants
        Page 5
    Table 5. Effects of MGA (melengestrol acetate) in the ration of growing beef heifers on pasture
        Page 6
    Table 6. Effects of MGA (melengestrol acetate) in the ration of finishing beef heifers
        Page 7
    Table 7. Estrus data for the MGA (melengestrol acetate) beef heifer studies
        Page 8
    Table 8. Effects of MGA (melengestrol acetate) on the carcass traits of beef heifers
        Page 9
    Table 9. Summary of combined growing and finishing phases of MGA (melengestrol acetate) beef heifer studies
        Page 10
Full Text




WEST FLORIDA EXPERIMENT STATION MAY 7 1968
Jay, Florida
May, 1968

WFES Mimeo Report 68-4*_-- .

THE VALUE OF MELENGESTROL ACETATE (MGA) IN THE RATION OF BEEF HEIFERS -/

J. E. Bertrand 2/


Numerous studies have been conducted with hormones or hormone-like products
to determine their effects on the performance of growing and finishing steers.
However, only a few studies have been conducted to evaluate similar products in
the growth and finishing of heifers.

MGA (melengestrol acetate) has a biological action which closely resembles
that of progesterone (the hormone of pregnancy). Research reports to date indicate
that it has the ability to stimulate gain, improve feed efficiency, and suppress
estrus when fed in relatively small quantities (0.2 to 0.5 mg. per head daily) to
feedlot heifers.

A summary of twenty-five finishing trials in which MGA, fed within the treat-
ment range of 0.2 to 0.5 mg. per head daily, was tested with beef heifers is pre-
sented in Table 1. Note that the average improvement in gain was 11.2% and the
average improvement in feed required to produce a unit of gain was 7.5% for the
heifers receiving the drug.

Heifers fed MGA, within the treatment range of 0.2 to 0.5 mg. per head daily,
gained on the average 6.9% more weight and required on the average 5.6% less feed
per unit of gain than heifers fed 10 mg. of DES (diethylstilbestrol) per head daily
(Table 2).

A summary of three finishing trials in which MGA, fed within the treatment
range of 0.2 to 0.5 mg. per head daily, was compared to implanted DES (12 to 24 mg.
per head) is presented in Table 3. Heifers fed MGA gained on the average 8.4% more
weight and were on the average 6.7% more efficient in converting feed to gain than
heifers implanted with DES.

However, when the performance of heifers fed MGA, within the treatment range
of 0.2 to 0.5 mg. per head daily, was compared to the performance of heifers im-
planted with Synovex-H (20 mg. of estradiol benzoate and 200 mg. of testosterone
propionate) an improvement in favor of the animals receiving MGA did not occur
(Table 4). Heifers implanted with Synovex-H gained on the average 4.0% more weight
and were 4.2% on the average more efficient in converting feed to gain than heifers
fed MGA.

In the great majority of the observations, the incidences of estrus (heat or
riding) were reduced in the heifers fed the MGA when compared to the other treat-
ments (control no drug, oral DES, implanted DES, and implanted Synovex-H).

1/ Presented at the 1968 Beef Cattle Short Course, University of Florida,
Gainesville.
2/ Associate Animal Scientist.








-2-


There did not appear to be any MGA related effects in all the above compari-
sons on any of the carcass traits studied.

MGA (Melengestrol Acetate) Beef Heifer Growing and Finishing Experimental
Results --- West Florida Experiment Station, Jay

Grbwing Phase

The performance and economic data for the growing or pasture phase of the
trial are listed in Table 5. The data on estrus are listed in Table 7.

It can be noted in Table 5 that the groups fed MGA (0.35 mg./head/day) gained
slightly faster than the control groups, 1.91 compared to 1.84 lb. per head daily,
and had a slight advantage in converting the concentrate supplement fed on pasture
to gain. The profit per head, not including labor or cost of the drug where appli-
cable, was $12.13 for the control groups compared to $14.05 for the groups fed MGA.

Estrus (heat or riding) was more prevalent in the control heifers than in the
heifers receiving MGA (Table 7).

Finishing Phase

The performance and economic data for the finishing phase of the trial are
listed in Table 6. The carcass data are listed in Table 8 and the data on estrus
are listed in Table 7.

It can be noted in Table 6 that the control heifers gained slightly faster
than the heifers receiving the 0.35 mg./head/day of MGA (2.09 compared to 2.01 lb.
per head daily, respectively). The control animals also converted feed to gain
slightly more efficiently.

However, the heifers receiving the MGA had a significantly (P<0.05) higher
carcass yield and graded slightly higher than the control heifers (Table 8). Since
the heifers were sold by the carcass on a grade and yield basis, the heifers
receiving the drug were worth more money. The profit per head for the finishing
phase of the trial, not including labor or cost of the drug where applicable, was
$6.33 for the control groups compared to $10.43 for the groups fed MGA (Table 6).

There was more suppression of estrus (heat or riding) in the heifers receiving
MGA than in the control heifers (Table 7).

Combined Growing and Finishing Phases

By combining the data for the growing and finishing phases, it can be noted
in Table 9 that the heifers fed MGA (0.35 mg./head/day) gained slightly faster than
the control heifers (1.94 compared to 1.90 lb. per head daily, respectively). The
profit per head for the combined phases, not including labor or cost of the drug
where applicable, was $24.29 for the heifers fed MGA compared to $18.45 for the
control heifers.









Table 1


A Summary of MGA (Melengestrol Acetate) Bee ~ eifer
Finishing Trials --- MGA Versus No Drug

Av. daily gain, lb. Feed/gain, lb.
Location Control MGA Control MGA
1. Upjohn Res. Farm 2.23 2.40 11.55 10.52
2. Upjohn Res. Farm 2.54 2.74 8.39 7.96
3. Upjohn Res. Farm 1.88 2.23 9.10 8.26
4. Upjohn Res. Farm 1.89 1.95 7.58 7.52
5. Upjohn Res. Farm 2.20 2.56 7.33 6.66
6. Iowa State U. 2.20 2.53 9.27 8.49
7. Iowa State U. 2.36 2.55 8.11 7.76
8. Texas Tech. College 1.72 1.85 14.90 13.70
9. Texas Tech. College 1.92 2.32 11.54 10.28
10. Michigan State U. 1.96 2.04 8.91 9.13
11. Michigan State U. 1.91 2.22 ----- -----
12. U. of Manitoba 2.68 2.88 7.48 7.38
13. U. of Saskatchewan 2.34 2.63 10.80 9.68
14. U. of Arizona 2.04 2.12 9.88 9.63
15. U. of Arizona 2.42 2.79 8.62 7.48
16. Field Trial (Colo. State U.) 1.91 2.16 --- --
17. Field Trial (U. of Calif.) 1.26 1.53 --- ---
18. Field Trial (U. of Calif.) 2.52 2.52 ---- ---
19. Field Trial (U. of Calif.) 2.13 2.29 9.64 8.58
20. Field Trial (U. of Calif.) 2.03 2.33 9.29 8.39
21. Field Trial (Iowa) 2.56 2.98 8.88 7.74
22. Field Trial (Midwest) 2.12 2.36 7.21 6.84
23. Field Trial (Kansas) 2.21 2.47 9.72 8.90
24. Field Trial (Iowa) 2.05 2.34 7.65 7.02
25. Field Trial (Indiana) 2.56 2.93 7.12 6.68
AVERAGES 2.15 2.39 9.19 8.50
IMPROVEMENT 11.2% 7.5%

(1) Twenty-five trials with averages of all pens fed MGA (melengestrol
acetate), within treatment range of 0.2 to 0.5 mg. per head daily,
compared to pens not fed the drug.









Table 2


A Summary of MGA (Melengestrol Acetate) Beef Heifer (
Finishing Trials --- MGA Versus Oral DES (Diethylstilbestrol)


Location


Michigan State U.
Michigan State U.
Field Trial (Colo. State U.)
Field Trial (Colo. State U.)
Field Trial (Colo. State U.)
Field Trial (Colo. State U.)
Field Trial (U. of Calif.)
Field Trial (Iowa)
Field Trial (Kansas)
Field Trial (Iowa)
AVERAGES
IMPROVEMENT


Av. daily gain, lb.,
DES MGA
1.83 2.04
2.22 2.28
1.71 1.96
2.67 2.68
2.41 2.48
2.34 2.50
1.45 1.53
2.75 2.98
2.31 2.47
2.12 2.34
2.18 2.33
6.9%


Feed/gain, Ib.
DES MGA
9.47 9.13
8.80 8.73
12.30 10.40
10.36 10.06
10.29 10.15
9.91 9.38
----- -----
8.38 7.74
9.42 8.90
7.49 7.02
9.60 9.06
5.6%


1.
2.
3.
4.
5.
6.
7.
8.
9.
10.



(1)


Ten trials with averages of all pens fed MGA (melengestrol acetate),
within treatment range of 0.2 to 0.5 mg. per head daily, compared to
averages of all pens fed DES (diethylstilbestrol) at the approved
treatment level of 10 mg. per head daily.









Table 3


A Summary of MGA (Melengestrol Acetate) Beef Heifer Finishing
Trials --- MGA Versus Implanted DES (Diethylstilbestrol)


Location
1. U. of Arizona
2. Michigan State U.
3. Field Trial (Calif.)
AVERAGES
IMPROVEMENT


Av. daily gain, lb.
DES MGA
2.48 2.79
2.14 2.22
2.12 2.32
2.25 2.44
8.4%


Feed/gain, lb.
DES MGA
7.89 7.48

10.30 9.50
9.10 8.49
6.7%


(1) Three trials with MGA (melengestrol acetate) fed within treatment
range of 0.2 to 0.5 mg. per head daily compared to implanted DES
(diethylstilbestrol) at levels of 12 to 24 mg. per head.





Table 4

A Summary of MGA (Melengestrol Acetate) Beef Heifer Finishing
Trials --- MGA Versus Synovex-H Implants(1)


Location


Field Trial (U. of
Field Trial (U. of
Field Trial (U. of
AVERAGES
IMPROVEMENT


Calif.)
Calif.)
Calif.)


Av. daily gain, lb.
Synovex-H MGA
2.54 2.52
2.52 2.29
2.38 2.33
2.48 2.38
-4.0%


Feed/gain, lb.
Synovex-H MGA

7.93 8.58
8.37 8.39
8.15 8.49
-4.2%


(1) Three trials with MGA (melengestrol acetate) fed within treatment
range of 0.2 to 0.5 mg. per head daily compared to implanted
Synovex-H (20 mg. of estradiol benzoate and 200 mg. of testosterone
propionate).









Table 3


A Summary of MGA (Melengestrol Acetate) Beef Heifer Finishing
Trials --- MGA Versus Implanted DES (Diethylstilbestrol)


Location
1. U. of Arizona
2. Michigan State U.
3. Field Trial (Calif.)
AVERAGES
IMPROVEMENT


Av. daily gain, lb.
DES MGA
2.48 2.79
2.14 2.22
2.12 2.32
2.25 2.44
8.4%


Feed/gain, lb.
DES MGA
7.89 7.48

10.30 9.50
9.10 8.49
6.7%


(1) Three trials with MGA (melengestrol acetate) fed within treatment
range of 0.2 to 0.5 mg. per head daily compared to implanted DES
(diethylstilbestrol) at levels of 12 to 24 mg. per head.





Table 4

A Summary of MGA (Melengestrol Acetate) Beef Heifer Finishing
Trials --- MGA Versus Synovex-H Implants(1)


Location


Field Trial (U. of
Field Trial (U. of
Field Trial (U. of
AVERAGES
IMPROVEMENT


Calif.)
Calif.)
Calif.)


Av. daily gain, lb.
Synovex-H MGA
2.54 2.52
2.52 2.29
2.38 2.33
2.48 2.38
-4.0%


Feed/gain, lb.
Synovex-H MGA

7.93 8.58
8.37 8.39
8.15 8.49
-4.2%


(1) Three trials with MGA (melengestrol acetate) fed within treatment
range of 0.2 to 0.5 mg. per head daily compared to implanted
Synovex-H (20 mg. of estradiol benzoate and 200 mg. of testosterone
propionate).








Table 5


Effects of MGA (Melengestrol Acetate) in the Ration
of Growing Beef Heifers on Pasture

Control MGA (a)
No. of animals 30(b) 29(b)(c)
Length of feeding, days 129 129
Av. initial wt., lb. 529.8 521.7
Av. final wt., lb. 767.0 767.6
Av. gain/animal, lb. 237.2 245.9
Av. daily gain, lb. 1.84 1.91
Concentrate/cwt. gain (d) 366.0 353.0
Feed cost/cwt. gain
Concentrate (e) $ 9.37 $ 9.04
Pasture (f) 7.32 7.05
Total $ 16.69 $ 16.09
Av. cost/head of feeder (g) $117.03 $115.24
Av. feed cost/head of feeder 39.58 39.58
Total cost/head of feeder (h) $156.61 $154.82
Gross value/head (i) $168.74 $168.87
Profit per head (h) +$ 12.13 +$ 14.05
(a) Melengestrol acetate --- fed at the level of 0.35 mg./
head/day.
(b) Three groups of ten animals each per treatment (the
three groups grazed 5 acres each of Argentine bahiagrass,
Pensacola bahiagrass, and Gahi-1 millet pastures,
respectively).
(c) One animal was diagnosed wrong while palpating for
pregnancy and lost a calf during the course of the study;
therefore, the data for that animal were disregarded.
(d) Concentrate supplement was fed on pasture at the level
of 1% of bodyweight.
(e) Concentrate supplement cost = $51.22/ton.
(f) Pasture cost = $33.36/acre for bahiagrass and $37.50/
acre for millet. Additional animals were grazed on the
millet pastures as required for best utilization of good
quality forage; nevertheless, total cost of pasture was
charged to the experiment.
(g) Feeder (heifer) cost of $22.09/cwt. (includes initial
cost of heifers, veterinary cost, hauling from auction
barn, pregnancy testing, and Bangs testing).
(h) Does not include labor or cost of the drug where
applicable.
(i) Based on an animal value of $22.00/cwt., which was the
sales value of slaughter heifers of that size and quality
at that time.









Table 6


Effects of MGA (Melengestrol Acetate) in the
Ration of Finishing Beef Heifers


No. of animals
Length of feeding, days
Av. initial wt., lb.
Av. final wt., lb.
Av. gain/animal, lb.
Av. daily gain, lb.
Feed/cwt. gain
Concentrate
Bahiagrass hay (c)
Feed/animal/day, lb.
Concentrate
Bahiagrass hay (c)
Feed cost/cwt. gain
Concentrate (d)
Bahiagrass hay (c)(e)
Bahiagrass pasture (f)
Total
Av. cost/head of feeder (8)
Av. feed cost/head of feeder
Total cost/head of feeder (h)
Gross sales/head (i)
Profit per head (h)
Av. price/cwt. on foot
Av. price/cwt. carcass


Control
30(b)
40
767.0
850.7
83.7
2.09

863.2
92.8


MGA (a)
30(b)
40
769.7
850.2
80.5
2.01

920.7
107.9


18.06 18.26
1.93 1.89


$ 20.23
1.39
1.47
$ 23.09
$168.74
19.33
$188.07
$194.40
+$ 6.33
$ 22.85
$ 40.85


$ 21.58
1.62
1.36
$ 24.56
$169.33
19.49
$188.82
$199.25
+$ 10.43
$ 23.44
$ 40.94


(a) Melengestrol acetate --- fed at the level of 0.35 mg./
head/day.
(b) Two groups of 15 animals per treatment -- one group in
each treatment was finished on pasture while the other
group was finished in drylot.
(c) The animals finished in drylot received bahiagrass hay.
(d) Concentrate ration cost = $46.87/ton.
(e) Bahiagrass hay cost = $30.00/ton.
(f) Bahiagrass pasture cost = $7.41/acre.
(g) Based on an animal value of $22.00/cwt.
(h) Does not include labor or cost of drug where applicable.
(i) Animals sold to Haas-Davis Packing Co., Inc., Mobile,
Alabama on a grade and yield basis.







Table 7

Estrus Data for the MGA (Melengestrol Acetate) Beef Heifer Studies


I. Growing Phase of the Trial

Control MGA (a)
ABG(b) PBG(C) Millet(d) ABG(b) PBG(C) Millet(d)
No. of animals 10 10 10 10 10 9(e)
Length of feeding, days 129 129 129 129 129 129
No. of estrous cycles observed 9 3 7 1 0 6
Totals for growing phase 19 7

II. Finishing Phase of the Trial

Control MGA (a)
Drylot Pasture(f) Drylot Pasture(f)
No. of animals 15 15 15 15
Length of feeding, days 40 40 40 40
No. of estrous cycles observed 4 10 6 5
Totals for finishing phase 14 11

Grand Totals 33 18

(a) Melengestrol acetate
(b) Argentine bahiagrass pasture
(c) Pensacola bahiagrass pasture
(d) Gahi-l millet pasture
(e) One animal was diagnosed wrong while palpating for pregnancy; the data for that
animal were disregarded during the growth phase.
(f) Argentine and Pensacola bahiagrass pasture.









Table 8


Effects of MGA (Melengestrol Acetate) on the Carcass
Traits of Beef Heifers


Av. slaughter wt., Ib (c)
Av. carcass wt., Ib. (d)
Av. dressing percent (carcass yield)
Av. conformation grade f)
Av. quality grade (f)
Av. Federal grade (f)
Av. marbling (8)
Av. ribeye area (sq. in.)
Av. ribeye area (sq. in.)/cwt. carcass
Av. maturity (h)
Av. color of lean ()
Av. color of fat ()
Av. estimated yield closely trimmed
boneless rib, ch ck, loin, rump,
and round (%) (k


Control(a)
850.7
475.9
55.9
15.2
14.9
14.6
10.6
10.62
2.23
2.4
3.4
2.7


51.05


(a) One group of 15 animals in each treatment was finished on pasture
while the other group of 15 animals was finished in drylot.
(b) Melengestrol acetate --- fed at the level of 0.35 mg./head/day.
(c) Weight off of experiment after an overnight shrink.
(d) Paying weight, which is hot dressed weight less 3%.
(e) Significant at Pc 0.05.
(f) 13 = low good, 14 average good, 15 = high good, 16 = low choice,
17 average choice, etc.
(g) 9 = slight+, 10 = small", 11 small, 12 = small+, 13 modest",
etc.
(h) 1 = A-, 2 = A, 3 = A+, 4 B-, etc. (age designation, A- to A+ =
10 months to 24 months of age, approximately).
(i) 2 = very light cherry red, 3 light cherry red, 4 slightly
dark red, etc.
(j) 1 a white, 2 cream, 3 = slightly yellow, and 4 very yellow.
(k) By formula -- est. percent yield = 51.34 5.78 (fat cover over
eye) 0.462 (% kidney fat) + 0.74 (rib eye area) 0.0093
(chilled carcass weight).


MGA(a) (b)
850.2
486.7
57.2(e)
15.5
15.2
14.8
10.8
11.05
2.27
2.2
3.5
2.5


51.04


__ __










Table 9

Summary of Combined Growing and Finishing Phases of
MGA (Melengestrol Acetate) Beef Heifer Studies


No. of animals
Length of feeding, days
Av. initial wt., lb.
Av. final wt., lb.
Av. gain/animal, lb.
Av. daily gain, lb.
Total feed cost/cwt. gain (c)
Av. cost/head of feeder (d)
Av. feed cost/head of feeder
Total cost/head of feeder (e)
Gross sales/head (f)
Profit per head (e)


Control
30
169
529.8
850.7
320.9
1.90
$ 18.36
$117.03
58.92
$175.95
194.40
+$ 18.45


MGA(a)
30(b)
169
521.7
850.2
328.5
1.94
$ 18.18
$115.24
59.72
$174.96
199.25
+$ 24.29


(a) Melengestrol acetate --- fed at the level of 0.35 mg./
head/day.
(b) The data for only 29 animals were considered during the
growing phase.
(c) Includes concentrate rations, hay, and pastures.
(d) Feeder (heifer) cost of $22.09/cwt. (includes initial
cost of heifers, veterinary cost, hauling from auction
barn, pregnancy testing, and Bangs testing).
(e) Does not include labor or cost of drug where applicable.
(f) Animals sold to Haas-Davis Packing Co., Inc., Mobile,
Alabama on a grade and yield basis.




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