Influence of energy level, weight at slaughter and castration on carcass quality in cattle

Livestock Production Science, 11 (1984) 571--586

571

Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

INFLUENCE OF ENERGY LEVEL, WEIGHT AT SLAUGHTER AND CASTRATION ON CARCASS QUALITY IN CATTLE

H. R E F S GAAR D ANDERSEN and K. LONNE I N G V A R T S E N

National Institute of Animal Science, Dept, of Research in Cattle and Sheep, Postbox 39, 8833 ~rum S¢~nderlyng (Denmark) SIGNE KLASTRUP

Danish Meat Research Institute, Magleg~rdsvej 2, 4000 Roskilde (Denmark) (Accepted 22 May 1984)

ABSTRACT Andersen, H.R., Ingvartsen, K.L. and Klastrup, S., 1984. Influence of energy level, weight at slaughter and castration on carcass quality in cattle. Livest. Prod. Sci., 11: 571--586. Carcass quality was examined in an experiment using 120 animals of the Danish Friesian breed (SDM). It was carried o u t as a 4 × 4 x 2 factorial experiment with four feeding levels (ad libitum, 85%, 70% and 70%/ad libitum), four slaughter live weights (425, 550, 675 and 800 kg) and two sexes (bulls and steers). The restrictive feeding levels were 85% and 70% of the expected ad libitum consumption level. The 70%/ad libitum group was fed at 70% of the ad libitum level until the animals were 125 kg below the determined slaughter weight and hence fed ad libitum for the rest of the feeding period. Increasing live weight at slaughter from 425 to 800 kg improved the dressing percentage as well as the conformation score, The carcasses became fatter, the relative weight of the bone decreased and the lean/bone ratio increased as the carcasses grew heavier. The relative weight of the " p i s t o l " cut was reduced with increasing weight. Compared with ad libitum feeding, restricted feeding reduced the dressing percentage as well as the conformation score. At a given carcass weight restricted feeding caused a reduction in the relative weight of fat and an increase in that of bone. On the other hand, lean/bone ratio and the relative weight of the 'pistol' cut were unaffected by feeding level. Slaughter weight x feeding level interaction was not significant for any of the characteristics. Castration had no significant influence on dressing percentage and conformation score. However, the carcasses from steers contained considerably more fat, less lean and slightly less bone than carcasses from bulls. Therefore the lean/bone ratio, and more especially the lean/fat ratio, were decreased by castration. These differences in carcass composition between the sexes became more and more pronounced with increasing carcass weights. The lean/fat ratio was reduced more by decreasing feeding level in bulls than in steers. The relative weight of the 'pistol' cut was not significantly different between bulls and steers. Compared to 70% feeding level during the whole fattening period finishing improved the carcass quality. The carcass characteristics of the 70%/ad libitum animals were comparable to those of the animals fed 85% o f ad libitum during the whole period.

0301-6226/84/$03.00

© 1984 Elsevier Science Publishers B.V.

572 INTRODUCTION

Obtaining desirable carcass quality is of great economic importance in beef production and it is important to k n o w how the carcass' characteristics are affected by the m e t h o d o f production. In Denmark since 1969 a project has been carried o u t with the aim to examine and quantify the effect of energy level, weight at slaughter and sex on growth, feed efficiency, carcass and meat quality. The background for the project and results on growth and feed efficiency have been published previously (Andersen and Ingvartsen, 1984) while the results concerning carcass quality are presented in this paper. Further, details of the project have been collected and presented in Danish by Andersen et al. (1983). MATERIALS AND METHODS

One hundred and t w e n t y calves of the Danish Friesian breed (SDM) were used. At 73 days of age the calves entered a 4 X (4) X 2 factorial experiment comparing f o u r feeding levels (ad libitum, 85%, 70% and 70%/ad libitum), four slaughter weights (425, 550, 675 and 800 kg) and t w o sexes (bulls and steers). The feeding levels comprised three levels, with one group with ad libitum feeding (100%), and t w o groups fed 85% and 70%, respectively, of the expected ad libitum consumption. The fourth group (70%/ad libitum) was fed as group 70% until 125 kg below the determined slaughter weight, and hence fed ad libitum for the rest of the period. None of the steers and bulls fed 70%/ad libitum were slaughtered at 800 kg. Castrations were performed at 3--4 m o n t h s of age. The energy concentration in the rations for the four feeding levels was nearly the same. Concentrate and beets, were restricted with the same percentage in all the restrictive groups. Only the amounts of straw and hay (0.4--2.5 kg according to live weight) were the same for all feeding regimes. The daily intake of energy at different live weights on each of the feeding regimes are presented in the previous paper (Andersen and Ingvartsen, 1984). After slaughter the carcasses were cooled at 6°(] for 24 hr and then kept at 4°(] (Buchter, 1976). The day after slaughter the carcasses were graded according to both the Danish and the EAAP classification system. Two days after slaughter the carcasses were weighed w i t h o u t liver, kidney, kidney fat and tail. The right side of each animal was divided into sixteen cuts, which were separated into lean, fat and bone (Andersen et al., 1977). In the following the results concerning the lean, fat and bone in the whole carcass and in three groups are presented. The three groups were: I, flank + brisket + fiat ribs + shin; II, forerib + neck + shoulder; III, pistol (see Fig. 1). The m. longissimus dorsi (LD) was photographed between the 1st and 2nd lumbar vertebrae to measure the muscle area and fat thickness.

573

Group ,III (pistol) 1

Top round

2

Bottom

3

Eye of round

4

Tip muscle

5

Heel

6

Round

round

of round bone

7

Hindshank

8

Rump

9

Sirloin

i0

and rump

Primerib

Group ll

steak

II

Forerib

12

Neck

13

Shoulder

Group

I

14

Flank

15

Flatribs

16

Shin

+ brisket

Fig. I. Method of cutting.

T h e c a r c a s s quality traits w e r e a n a l y s e d a c c o r d i n g t o t h e f o l l o w i n g m o d e l :

Yijkmn

= l~ + S L i + Ij + K k + F m + ( S L . K ) i k + ( S L ' F ) i m + (I" K ) ~ +

(/-F)j m + (K.F)k m + (SL.I.K)ijk

+ eijkm n,

where:

# SL i

Fm

= = = = =

population mean e f f e c t o f w e i g h t g r o u p , I = 1, 2, 3 e f f e c t o f f e e d i n g level, j = 1, 2, 3, 4 e f f e c t o f sex, k = 1, 2 e f f e c t o f sire, m = 1, 2, 3

574

(SL'I)ij (SL.K)i k (SL. F)im

= = = = (I'g)jk = = (K'F)km (SL'I'K)ijk =

(I"F/ m

effect effect effect effect effect effect effect

of of of of of of of

w e i g h t × f e e d i n g level i n t e r a c t i o n w e i g h t X sex i n t e r a c t i o n w e i g h t × sire i n t e r a c t i o n f e e d i n g level × sex i n t e r a c t i o n f e e d i n g level × sire i n t e r a c t i o n sex × sire i n t e r a c t i o n w e i g h t × f e e d i n g level × sex i n t e r a c t i o n

= error,N (o, 0 5)

eijkrnn

T h e 8 0 0 kg groups w e r e n o t i n c l u d e d in this m o d e l as n o steers were slaughtered at 800 kg. T h e changes in carcass c o m p o s i t i o n t h a t o c c u r d u r i n g g r o w t h were estim a t e d a c c o r d i n g t o a m o d i f i e d a l l o m e t r i c f u n c t i o n w h i c h was t r a n s f o r m e d to the f o l l o w i n g linear m o d e l : log Yjkmn = log # + log Ij + log K k + log F m + bjk" log X + log ejkmn where: log

log ~ log/£k log F m log X bjk

= intercept (expressed as log) = effect of feeding level (log), j = 1, 2, 3, 4 = effect of castration (log), k = 1, 2 = effect of sire (log), m = i, 2, 3 = independent variable transformed to log = growth coefficient for bulls or steers (k) fed at feeding level

l o g ejkrn n

=

(J) error (log)

The results presented in the figures were calculated as follows: Yjk

=a

•

b

jk Xjk 62.5

62.5

d

oj D~ 4J oj U A n d e r s e n ,

~

1 9 7 5

4J

° ~ ° "

"'"

~57.5

d

~u 80.0

60.0

~

~57.S

~"

~m

~' 55.0

?~55.o t~ IIJ

.

I:::

~52.5

c~ 52.5 50.0

50.0 , .........

. .........

w .........

. .........

. .........

. .........

, .........

Weight ,kg

. .........

•

---. .........

l .........

w .......

Weight ,kg

Fig. 2. Dressing percentage for bulls (d) and s t e e r s (~) dependent on feeding level and live w e i g h t at slaughter. F e e d i n g levels: - - , ad l i b i t u m ; - - - - --, 85% o f ad l i b i t u m •level; . . . . . , 7 0 % ; . . . . , 7 0 % / a d libitum.

575

4J

SO

u

............ ..~....

30

4~

10

100

lSO

g~O

250

~0

350

~

Carcass

4~0 weight,

250

300

350

4gX3

kg

Fig. 3. P e r c e n t a g e o f l e a n , f a t a n d b o n e f o r bulls (d) a n d steers ($) a t d i f f e r e n t f e e d i n g levels a n d carcass weights. F e e d i n g levels: - - - , ad l i b i t u m , - - - - --, 85% o f a d l i b i t u m level; . . . . . , 7 0 % ; . . . . , 7 0 % / a d l i b i t u m .

where: Yjk

~k bjk

= estimated value for bulls or steers (k) fed at feeding level (j) --

U-Ij.Kk-

independent variable

= growth coefficient for bulls or steers (k) fed at feeding level (j)

The dressing percentages (Fig. 2) are calculated from estimated carcass weights according to the parameters in Table II and live weights. Likewise the weight of lean, fat and b o n e at different carcass weights are calculated from the parameters in Table III. On basis of these results the relative c o n t e n t of lean, fat and b o n e are calculated and presented in Fig. 3, while the lean/bone and lean/fat ratio are presented in Fig. 4. The results from the earlier experiment (Andersen, 1975) comparing animals up to a live weight of 540 kg at slaughter are given in the left side of Figs. 2, 3 and 4.

576 Lean~bone

ratio

5

4 3

4

2 .......

100

Lean~fat

e........

i. . . . . . . .

| . . . . . . . . . i ........ | ......... , . . . . . . . .

200

250

A n d e r s e n ,

1 9 7 5

150

300

350

400

--i . . . . . . . . , ........ w . . . . . . .

|--

450

250

3OO

350

,--

4OO

r a t i o

-/

G

5

4

3 <--

--~

2

1 i .........

100

i ........

150

I . . . . . . .

200

i . . . . . . . .

250

i ........

300

i .........

350

i .........

tOO

Carcass

i..

---i

450

weight,

.........

250

i .........

300

i .........

350

i..

400

kg

Fig. 4. Lean/bone and lean/fat ratio of bulls (d) and steers ($) dependent on feeding level and carcass weight. Feeding levels: ~ , ad libitum; -- -- --, 85% of ad libitum level; . . . . . ,70%; . ~ , 70%/ad libitum.

RESULTS AND DISCUSSION

Effect of weight at slaughter The dressing percentage as well as the c o n f o r m a t i o n score was improved w i t h increasing w e i g h t at slaughter (Fig. 2 and Tables I and II). This is in agreement w i t h results from previous e x p e r i m e n t s w i t h ad libitum-fed Red Danish and Danish Friesian bulls ( A n d e r s e n et al., 1 9 7 7 ; Andersen et al., 1 9 8 1 ; S t r u d s h o l m et al., 1 9 8 2 ; Liboriussen et al., 1 9 8 2 ) . Based o n these results Andersen et al. ( 1 9 8 3 ) c o n c l u d e d that the dressing percentage and

577 TABLE I T h e i n f l u e n c e o f w e i g h t a t s l a u g h t e r , f e e d i n g level and s e x o n carcass c l a s s i f i c a t i o n , and m e a s u r e m e n t s o f carcass q u a l i t y (least s q u a r e m e a n s - - m o d e l I) Classification

R 2-value

Measurements

Conformation Danish* E A A P * *

F a t n e s s * * * Carcass EAAP length, cm

Area of LD, c m 2

Fat thickness, mm

45

77

77

75

44

96

Live w e i g h t (SL) 425 6.6 a 550 7.2 ab 675 7.6 b

7.5 a 8.0 a 8.2 a

7.0 a 7.0 a 9.2 b

117 a 126 b 133 c

56.5 a 66.8 b 73.4 c

5.4 a 7.6 b 13.0 c

F e e d i n g level 100 7.5 a 85 6.5 b 70 6.6 b 70/100 7.8 a

8.5 a 7.9 ab 7.3 b 8.0 ab

9.4 a 8.1 b 5.7 c 8.7 ab

125 a 127 b 127 b 124 a

63.6 a 64.4 a 67.2 a 67.0 a

10.3 a 9.3 a 6.6 b 8.5 ab

6.9 a 9.1 b

126 a 125 a

68.2 a 62.9 b

6.3 a 11.0 b

NS S NS NS

NS (0.60) NS(0.34) NS (0.75) NS (0.11)

NS S NS NS

Sex (K) Bulls

7.3 a

8.0 a

Steers

7.0 a

7.9 a

Interactions SLx I SLx K IXK SLX Ix K

NS NS NS NS

(0.87) NS (0.67)NS ( 0 . 8 9 ) NS ( 0 . 8 8 ) NS

(0.33) (0.96) (0.21) (0.44)

NS ( 0 . 1 6 ) S (0.01) S (0.01) NS ( 0 . 6 1 )

(0.11) (0.05) (0.19) (0.55)

(0.37) (0.01) (0.25) (0.14)

* C o n f o r m a t i o n : AI = 10, A ÷ = 9, A ffi 8, A - = 7 etc. * * C o n f o r m a t i o n ( E A A P ) : P o i n t s 1 - - 1 5 : 1 5 best. ***Fatness (EAAP): Points 1--15:15 fattest. ab,cValues bearing d i f f e r e n t s u b s c r i p t s in t h e same c o l u m n are significantly d i f f e r e n t (P < 0.05). Values in p a r e n t h e s e s give P ( F ~ Fobs).

conformation score for ad libitum fed bulls can be expected to increase 1.0 to 1.2 percentage units and 0.4 to 0.6 points respectively for every 100 kg increase in slaughter weight. Also the fat cover and the fat thickness was increased with slaughtering at higher weights. The differential growth of lean, fat and bone as shown in the previous paper (Andersen and Ingvartsen, 1984) causes carcass composition to change with the weight at slaughter. Accordingly the fat content increased substantiaUy while the relative content of lean and bone decreased as weight at slaughter went up (Table III and Fig. 3). This was especially true for the steers. The lean/bone ratio increased, but only slowly, with increasing weight (Fig. 4). Corresponding growth patterns were found in earlier experiments with serial slaughter (Andersen, 1975; Andersen et al., 1981;

578 TABLE II Parameter estimates from the allometric relationships (model II) for weight of carcass (Y) on live weight (X) Sex(K)

Feeding

Carcass weight

level(I)

a × 104

b

se b

Bulls

100 85 70 70/100

2870 2745 3617 2805

1.1097 1.1129 1.0689 1.1110

178 178 176 249

Steers

100 85 70 70/100

2498 2389 3148 2442

1.1311 1.1375 1.0908 1.1314

229 221 223 256

R ~-value

x 10"

99

Test for difference in b-value dependent on: K NS (0.27) I N S (0.21) K x I NS (0.12) Test for difference in level at average live weight (590 kg) dependent on: K N S (0.68)

x

s (0.00)

K x I

N S (0.08)

Liboriussen et al., 1982; Strudsholm et al., 1982). The three main cuts showed relatively different patterns o f development. For bulls as well as steers the relative weight of the pistol c u t (cut III) decreased while the cut including flank + brisket + flat ribs + shin (cut I) increased with increasing carcass weight. The relative weight of forerib, neck and shoulder (cut II) increased for bulls and decreased for the steers as weight at slaughter went up (see b-values in Table IV). For both sexes the pistol cut was a little leaner than the whole carcass. Cut II was somewhat leaner, and cut III considerably fatter than the whole carcass (Andersen et al., 1983). This is also in agreement with the previous experiment {Andersen, 1975).

Effect of feeding level Compared with ad libitum feeding, restricted feeding reduced the conformation score (Table I) as well as the dressing percentage (Table II and Fig. 2). Based on these results and those of the preceding experiment (Andersen, 1975) it has been estimated that the dressing percentage is reduced 0.4 to 0.6 percentage units and the conformation score 0.3 to 0.5 points

16618 14565 12177 13904

98

0.8170 0.8480 0.8846 0.8580

0.9263 0.9585 0.9956 0.9680

b

337 325 340 384

265 265 278 369

se b ×

104

57 64 63 76

206 232 229 277

a × 104

Fat

90

1.6658 1.6167 1.6023 1.5853

1.3898 1.3278 1.2849 1.2923

b

NS (0.77)

(K × I)

(o.0o)

s

i

s

(o.oo)

NS (0.63)

s

(o.o0)

NS (O.40)

× 104

1414 1366 1428 1613

1114 1113 1166 1551

se b

Test for difference in b-value dependent on: K S (0.00) S (0.02) S (0.02) I NS (0.32) NS (0.93) NS (0.96) (K × I) NS (0.95) NS (0.02) NS (0.50) Test for difference in level at average carcass weight (335 kg) dependent on: g S (0.00) S (0.00) S (0.00)

R ~-value

100 85 70 70/100

Steers

9831 8617 7204 8225

a × 104

level (I)

100 85 70 70/100

Lean

Feeding

Bulls

Sex (K)

7863 9232 10132 8749

4274 5018 5508 4756

a × 104

Bone

93

0.7197 0.7016 0.6877 0.7047

0.8280 0.8084 0.8017 0.8154

b

537 519 542 612

423 423 443 589

se b

× 104

Parameter estimates from the allometric relationships (model II) for lean, fat and bone (Y) on carcass weight (X)

TABLE III

LU ¢~

Cut I a x 104

1372 1655 1442 2158

743 899 783 1172

Feeding level (I)

100 85 70 70/100

100 85 70 70/100

98

1.2417 1.2011 1.2193 1.1576

1.1225 1.0808 1.0946 1.0359

b

434 419 438 495

342 342 358 476

se b

x 104

5265 3875 3131 2417

2520 1855 1499 1157

Cut II a x 104

98

0.8793 0.9376 0.9779 1.0163

1.0220 1.0815 1.1260 1.1615

b

352 340 355 401

277 277 290 386

se b x 10'

Test for difference in b-value dependent on: S (0.00) NS(0.50) K S (0.00) I NS (0.49) S (0.01) NS (0.36) (K x I) NS (0.56) NS (0.43) NS (0.91) Test for difference in level at average carcass weight (335 kg) dependent on: K S (0.00) S (0.00) NS(0.09) I S (0.00) S (0.00) NS(0.17) (K x I) NS (0.66) NS (0.27) NS (0.88)

R2-value

Steers

Bulls

Sex (K)

7088 7522 9278 8558

7660 8129 26 9249

Cut III a x 104

99

0.9160 0.9078 0.8729 0.8857

0.9019 0.8931 0.8572 0.8713

X 104

245 237 248 280

193 193 202 269

se b

Parameter estimates from the allometric relationships (model II) for cuts I, II and III (Y) on carcass weight (X)

TABLE IV

O0 CD

581 for every 100 g decrease in daily gain. The poorer conformation score at restrictive feeding is probably caused by the lower degree of fatness and longer carcasses (Table I). The relative content of lean, fat and bone in the carcass was strongly affected by the feeding level (Table III and Fig. 3). In contrast to the preceding experiment, where the animals were slaughtered at lower weights, the feeding level × weight interaction for fat and lean content was not significant in the present experiment, which might indicate that such interaction dilutes at higher weights. The effect of feeding level at 250 to 300 kg carcass weight was almost equal in the two experiments (Fig. 3). However, the fat content in group 70% and 85% was less and the lean content correspondingly higher in the present experiment compared to the previous indicating that animals in the present experiment were later matured than in the previous. Similarly, it was not the case for the animals of the groups fed ad libitum, but this is explainable by the earlier mentioned 10 to 20% higher feed intake by the ad libitum fed bulls in the present experiment. The lean/bone ratio was almost unaffected by feeding level (Fig. 4). The lean/fat ratio, on the other hand, was strongly reduced with increasing feeding level, especially for the bulls. SCrensen et al. (1972) and Frood and Owen (1972) also found that the lean/fat ratio was more strongly affected by feeding level in bulls than in steers. Neither in this experiment nor in the previous one (Andersen, 1975) was the relative weight of the pistol cut (III) significantly affected by feeding level. In contrast to this the relative weight of cut I was reduced, whereas the relative weight of cut II was increased by restricted feeding (Table IV). Reduction in the feeding level resulted in lowered fat content of all cuts, and more so in the fattest cut (cut I) than in cut II and III (Andersen et al., 1983).

Effect of castration Conformation score and dressing percentage were not significantly affected by castration (Table I and Fig. 2), and this is in agreement with earlier Danish experiments (Neimann-S¢rensen et al., 1967; SCrensen et al., 1972). However, fat cover and fat thickness were increased by castration while the area of LD was decreased. In the previous paper (Andersen and Ingvartsen, 1984) it was shown that castration causes a reduced carcass gain and a simultaneous increase in fat gain. Therefore the carcasses from steers contain considerably more fat, less lean and slightly less bone than bulls (see Fig. 3). This is in agreement with most results in the literature (e.g. Br~nr~ng, 1966; Turton, 1969; Br~[nn~ng et al., 1970). The significant differences in the b-values for sex in Table III indicate that the difference in carcass composition was increased with increasing

582

carcass weight (Fig. 3). This sex X weight interaction was also found by Berg (1967), Arthaud et al. (1977) and S¢rensen et al. {1972). The lean/ bone ratio and especially the lean/fat ratio was decreased by castration. The fact that the dally fat gain was more reduced by feeding level in bulls than steers (Andersen and Ingvartsen, 1984) explains why the lean/fat ratio in the carcass was more affected by feeding level in the bulls than steers (Fig. 3 ). Br~inn~ng (1966) and Turton (1969) concluded that the "hindquarter" is increased 1 to 2 percentage units by castration. In earlier Danish experiments comparing bulls and steers it was found that the pistol cut was increased less than 1 percentage unit by castration (Neimann-S~brensen et al., 1967; S~brensen et al., 1972). In the present experiment, however, the weight of the pistol cut was not significantly different between the two sexes. The reason for this discrepancy is probably that the pistol cut does not include the abdominal part of the carcass (see Fig. 1). The abdominal part was included in cut I and this cut was increased up to 3 percentage units by castration. All three cuts were fatter for the steers than for the bulls, but the difference was most pronounced for the fattest cut (I).

Effect of finishing All of the carcass quality characteristics measured were better for bulls and steers fed ad libitum for the last 125 kg before slaughter (70%/ad libitum) than for the animals fed 70% during the entire growth period. Most of the traits were comparable to the carcass characteristics of the animals in group 85%. However, compared to all other groups the bulls and steers fed ad libitum the last 125 kg before slaughter showed a trend for higher lean/bone ratio, and their conformation score was comparable to the animals fed ad libitum throughout the entire growth period. CONCLUSIONS AND RECOMMENDATIONS

As mentioned in the introduction this experiment is part of a project aiming to quantify the changes in growth feed efficiency, carcass and meat quality as dependent on slaughter weight and feeding level. A thorough knowledge of the role of these factors can be, to a wide extent, controlled and used by the producer. The following conclusions and recommendations are given.

Feeding level and weight at slaughter A d libitum feeding compared to restricted feeding of Red Danish ( R D M ) and Danish Friesian (SDM) young bulls causes a shorter fattening period, higher dressing percentage and a better carcass conformation. However,

583 high feeding level will give a somewhat worse feed conversion ratio as well as a certain risk of excessive fat cover when the animals are heavier than 425 kg at slaughter. For each 100 g increase in daily gain due to an increase in feeding level the dressing percentage and conformation score are expected to increase 0.5 percentage units and 0.4 points, respectively. For every 100 g increase in daily gain the FCR are expected to increase about 5% in the range from 75 to 100% of maximum intake. The listed advantages of the high feeding level will, in most instances, economically outweight the disadvantages. Therefore, it is recommended to feed bulls ad libitum during the whole fattening period. The advantages of increasing weight at slaughter are increased dressing percentage and better conformation score. The disadvantage is an increased feed conversion ratio. For bulls from 100 to 400 kg live weight the feed conversion ratio increases by about 1.3 Scandinavian feed units for every 100 kg gain. Dressing percentage and conformation score will increase approximately 1.1 percentage units and 0.5 points, respectively, for each 100 kg increase in weight. The economically optimal slaughter weight for bulls ranges from about 375 kg live weight using high concentrate feeding to 450 kg using relatively high roughage feeding. Questions concerning economy, especially optimal slaughter weights, are discussed in papers by Andersen and Strudsholm (1982a, b). B u l l s versus s t e e r s

Feed intake capacity can be expected to be the same for bulls and steers, but castration decreases the growth capacity. Dressing percentage and conformation score are unaffected by castration in animals of the same weight and feeding level. Fat cover as well as the fat content in the carcass is greater for steers than for bulls, especially at the higher weights. Dependent on feeding, castration of RDM and SDM is expected to reduce the growth capacity 12--18% between 3--.4 months of age and slaughter at 500 to 600 kg. Correspondingly the feed conversion ratio for steers fed high and moderate feeding levels will be 24 and 18% higher than for bulls. However, feed conversion ratio for ad libitum-fed bulls (1200 g daily gain) and restricted fed steers (800 g daily gain) axe almost equal. The longer growth period and higher feed conversion ratio for steers means that intensive fattening of steers during the whole feeding period can rarely give the economic return comparable to the production of bulls. Production of steers should not be recommended over production of bulls, unless feed prices are very low (extensive conditions) and/or the sales prices of steers are higher than those for bulls.

584

ACKNOWLEDGEMENTS This project was carried out with economic support from the EEC Beef Production Program. The Department gives its appreciation and sincere thanks to the Commission.

REFERENCES Andersen, B.B., Lykke, T.H., Kousgaard, K., Buchter, L. and Pedersen, J.W., 1977. Growth, feed utilization, carcass quality and meat quality in Danish dual purpose cattle. 453. beretn., Statens Husdyrbrugsfors~bg, Copenhagen, 86 pp. Andersen, H.R., 1975. Slagtevmgtens og foderstyrkens indflydelse p~i vmkst, foderudnyttelse og slagtekvalitet hos ungtyre. 430. beretn., Statens Husdyrbrugsfors~bg, Copenhagen, 124 pp. Andersen, H.R., Andersen, B.B., M~bller, E., Kousgaard, K. and Klastrup, S., 1981. K o m bineret avls- og fodringsfors~bg p~i avlsstationen "Egtved". c. FodHng reed majsensilage. Medd. nr. 366, Statens Husdyrbrugsfors~g, 4 pp. Andersen, H.R. and Strudsholm, F., 1982a. (Dkonomi og optimal afgangsvmgt i ungtyreproduktionen. 1. Gennemsnitsbetragtning. Medd. nr. 444, Statens Husdyrbrugsfor~g, 4 pp. Andersen, H.R. and Strudsholm, F., 1982b. ~konomi og optimal afgangsvmgt i ungtyreproduktionen. 2. Marginalbetragtning. Medd. nr. 445, Statens Husdyrbrugsfors~g, 4 pp. Andersen, H.R., Ingvartsen, K.L., Buchter, L., Kousgaard, K. and Klastrup, S., 1983. Influence of energy level, weight at slaughter and sex on growth, feed conversion, carcass composition and meat quality in cattle (With English summary and subtitles). 544. Report from the National Institute of Animal Science, Copenhagen, 145 pp. Andersen, H.R. and Ingvartsen, K.L., 1984. The influence of energy level, weight at slaughter and sex on growth and feed efficiency in cattle. Livest. Prod. Sci., 11:

559--569. Arthaud, V.H., Mandigo, R.W., Koch, R.M. and Kotula, S.W., 1977. Carcasscomposition, quality and palatability attributes of bulls and steers fed different energy levels and killed at four ages. J. Anita. Sci., 44: 53--64. Berg, R.T., 1967. Genetic and environmental influences on growth in beef cattle. In: G.A. Lodge and G.E. Lamming (Editors), Growth and Development of Mammals. Butterworths, London, pp. 429--450. Br/inn~ng, E., 1966. Studies on monozygous cattle twins XVIII. The effect of castration and age of castration on t h e growth rate, feed conversion and carcass traits o f Swedish red and white cattle. Part I. Lantbruksh6gsk. Ann., 32: 329--415. Br~/nn~ng, E., Henningsson, T., Liljedahl, L.-E. and Lindh~, B., 1970. Studies on monozygous cattle twins. XVI. The effect of castration and carcass traits of Swedish red and white cattle. Lantbruksh6gsk. Ann., 36: 91--113. Buchter, L., 1976. Determination of meat quality in cattle. In: Agricultural Research Seminar: Criteria and Methods for Assessment of Carcass and Meat Characteristics in Beef Production Experiments. Commission of the European Communities, Luxembourg, pp. 331--339. F r o o d , I.J.M. and Owen, E., 1972. Growth rate, feed conversion and carcass composition and quality of Friesian male, castrate and female cattle feed on all-concentrate diet and slaughtered at four live weights. 54th Meeting of the British Society of Animal Production. Proc. Br. Soc. Anita. Prod., 128 pp.

585 Liboriussen, T., Lauritzen, F., Andersen, B.B., Buchter, L., Klastrup, S., Kousgaard, K. and S#rensen, S.E., 1982. Krydsnings- og produktionsforsdg reed europmiske k~bdracer I og II. 527. beretn., Statens Husdyrbrugdorsbg, Copenhagen, 65 pp. Neimann~brensen, A., Kirsgaard, E., Agergaard, E., Klausen, S. and Larsen, J.B., 1967. Ungtyre contra stude. Forskellige kastrationsmetoder og forskellig foderstyrke p~ staid og grins. Arbog, Landbk. Fors~bgaiab., Copenhagen, pp. 517--525. Strudsholm, F., Andersen, H.R., Andersen, B.B., Mbller, E. and S~brensen, S.E., 1982. Kombineret avis- og fodringsfors~g p{t avlsstationen "Egtved". d. Fodring reed byghelssedsensilage til ungtyre. Medd. nr. 426, Statens Husdyrbrugsfors~g, 4 pp. Sqbrensen, M., Lykkeaa, J. and Andersen, H.R., 1972. Fodringsintensitetens indflydelse p~ tilvaekst og k~dkvalitet hos ungtyre og stude. Arbog, Land~bk. Forsbgslab., Copenhagen, pp. 370--376. Turton, J.D., 1969. The effect o f castration on meat production from cattle, sheep and pigs. In: D.N. Thodes (Editor), Mean production from entire male animals. Churchill Livingstone, London, pp. 1--50.

RESUME Andersen, H.R., Ingvartsen, K.L. et Klastrup, S., 1984. Influence du niveau d'alimentation, du poids d'abbatage et de la castration sur les qualit~s de carcasse des bovins. Livest. Prod. Sci., 1 1 : 5 7 1 - - 5 8 6 (en anglais). On a ~tudi~ les qualit~s de carcasse de 120 animaux de race Frisonne Danoise (SDM) utilis~s darts une experience factorielle 4 × 4 × 2 c o m p o r t a n t quatre niveaux d'alimentation (k volont~ 85%, 70% et 70%/~t volont~), quatre poids d'abattage (425, 5 5 0 , 6 7 5 et 800 kg) et deux "sexes" (boeufs et taureaux). Les animaux rationn~s recevaient 85 ou 70% du niveau estim~ d'ingestion ~ volont~. Le lot 70%/~ volont~ ~tait aliment~ au niveau 70% jusqu'k un p o i d s de 125 kg inf6rieur k celui de leur poids d'abattage, puis aliment~ ~ volont~ jusqu'k l'ahattage. L'accroiseement du poids vif k l'abattage de 425 k 800 kg a entrafn6 une am~Uoration du rendement en carcasse et de la note de conformation. Avec l'angmentation du poids de carcasse, celle~i est devenue plus grasse, la proportion d'os a diminu~ et le rapport muscle/os a augmentS. Le poids relatif des morceaux de l'arritre et du dos ("pistol") a diminu~ avec l'accroiesement du poids de carcasses, Par rapport au niveau d ' a l i m e n t a t i o n k volont6, la restriction du niveau ~nerg~tique a e n t r a ~ une diminution du r e n d e m e n t en carcasse et aussi de la note de conformation. A poids de carcaese donn~, la restriction alimentaire induit une r6duction de la proportion de d~p6ts adipeux et u n accroissement de la p r o p o r t i o n d'os. En revanche, le rapport muscle/os et la p r o p o r t i o n de m o r c e a u x de l'arri~re et du dos n ' o n t pas ~t~ modifl~es par le niveau alimentaire. Aucune interaction slgnificative n'est apparue entre le niveau d'allmentation et le poids 'd'ahattage p o u r aucun des paramttres mesur~s. La castration n'a pas eu d'influence significative sur le rendement en carcasse et la note de conformation. Cependant, les carcasses de boeufs contenaient beaucoup plus de d~p6ts adipeux, moins de muscles et l~g~rement moins d ' o s que celles des taureaux. C'est pourqui le r a p p o r t muscle/os et surtout le rapport muscles/graisse ont diminu~ sous l'effet de la castration. Ces d i f f ~ e n c e s entre "sexes" dans la composition des carcasses sont devenues de plus en plus importantes avec l'accroissement du poids de carcasse. Le rapport muscles/graisse a ~t~ davantage r£~duit sous l'effet d ' u n e diminution du niveau alimentaire chez les taureaux que chez les boeufs. La p r o p o r t i o n de morceaux de l'arri~re et du dos n'~tait pas significativement diff~rente entre les boeufs et |es taureaux.

586 Par rapport au niveau d'alimentation 70% durant t o u t e la p~riode, la phase de finition a augment~ les qualit~s de carcasse. Les caract~ristiques des carcasses des animaux du lot 70%/k volont~ ~taient voisines de celles des animaux ayant re~u le niveau alimentaire 85% durant toute la p~riode. KURZFASSUNG Andersen, H.R., Ingvartsen, K.L. und Klastrup, S., 1984. Einfluss des Energieniveaus, Schlachtgewicht und Kastration auf die SchlachtkSrperqualitiit yon Rindern. Livest. Prod. Sci., 1 1 : 5 7 1 - - 5 8 6 (auf englisch). In einem Versuch mit 120 Tieren der d~nische schwarzbunte Rasse (SDM) wurde die Schhchtk6rperqualit~t untersucht. Er war als 4 x 4 x 2 faktorieller Versuch angelegt mit vier Abstufungen des F~/tterungsniveaus (ad libitum, 85%, 70% und 70%/ ad libitum) vier Schhchtgewichten ( 4 2 5 , 5 5 0 , 6 7 5 und 800 kg) und zwei Geschlechtern (Bullen und Oehsen). Die Behandlungen mit beschr~nkter F~itterung betrugen 85% und 70% der erwarteten ad libitum Futteraufnahme. Die 70%/ad libltum Gruppe wurde auf dem Niveau 70% gef~fttert bis sie 125 kg weniger als das festgesetzte Schlachtgewicht erreicht hatte und dann ad libitum bis zum Ende des Mastperiode. Mit steigenden Schlachtgewichten yon 425--800 kg stieg sowohl die Schlachtausbeute als auch die Schlachtk~rperbenotung. Der Schlachtk6rper wurde fetter, der Knochenanteil sank und das Fleisch/Knochen-Verhi/ltnis stieg bei schwerer werdenden Schlachtk~rpern. Der prozentuale Anteil der "Pistole" sank mit steigendem Gewicht. Im Vergleich mit der ad libitum-F~itterung f~hrte die verhaltene F~/tterung zu niedrigerer Schlaehtausbeute und niedrigerer Einstufung des Schlaehtk6rpers. Bei gegebenem Schlachtk6rpergewicht f~fhrte die verhaltene F~itterung zu einer Verringerung des Fettanteils und einer Ausweitung des Knochenanteils. Das Fleisch/Knochen-Verh~ltnis und der Anteil der Pistolenschnitt am Schlaehtk~rper wurden nicht vom Ffitterungsniveau beeinflusst. Interaktion zwischen Schlachtgewicht und F~itterungsniveau war f/fr keines der Merkmale signifikant. Die Kastration hatte keinen signifikanten Einfluss auf die Schlachtausbeute und die Bewertung des Schhehtk~rpers. Die Schlachtk~rper yon Ochsen enthielten jedoch erheblich viel mehr F e t t , weniger Fleisch und geringfffgig weniger Knochen als die yon Bullen. Das Fleisch/Knochen Verhhltnis und insbesondere das Fleisch/Fett-Verh~ltnis wurde also dutch die Kastration verringert. Mit steigendem Schlachtk~rpergewicht wurden die Unterschiede zwischen den Geschlechtern in Bezug auf die Schlachtk~rperzusammensetzung grosset. Das Fleisch/FettVerhi/ltnis sank mit verhaltener F~/tterung, bei Bullen mehr als bei Ochsen. Der Anteil der Pistolenschnitt war nicht signifikant unterschiedlich zwischen Bullen und Ochsen. Gegen~fber dem F~ftterungsniveau 70% /iber die ganze Mastperiode verbesserte die abschliessende ad libitum-F~/tterung die Schlachtk~rperqualit~t. Die SchlachtkSrpermerkmale der Gruppe 70%lad libitum waxen dem der Tiere mit 85% der ad libitum F u t t e r a u f n a h m e ~/ber die ganze Mastperiode vergleichbar.