Effects of dietary tryptophan deficiency in finishing pigs, according to age or weight at slaughter or live weight gain

Livestock Production Science41 ( 1995) 63-76

Effects of dietary tryptophan deficiency in finishing pigs, according to age or weight at slaughter or live weight gain Y. Henry Institut National de la Recherche Agronomique, Station de Recherches Porcines, F-35590 Saint-Gilles, France

Received 11 January 1994; accepted 10 May 1994

Abstract Three experiments were conducted with 188 finishing pigs (females and castrated males) of the Large White breed, between mean body weights (BW) of 53 and 88 kg, and fed according to a feeding scale, to study the effects of dietruy tryptophan (‘I’RP) deficiency (0.10 vs. 0.13%) on feed intake, growth performance, body composition and tissue gain, and meat quality, according to age or B W at slaughter or BW gain. TRP deficiency depressed feed intake, growth performance, and tissue (muscle and fat) gains, with less pronounced effect with advancing age. Females were more sensitive to TRP deficiency than castrated males. The weights of lean and fat joints both decreased with TRP deficiency in pigs slaughtered at the same age, with no resulting change in carcass composition, while they were similar to those in control animals after slaughter at the same BW. The addition of dietary limiting TRP affected carcass conformation through preferential stimulation of development in depth (forehand, hindquarter) compared to development in length, thus producing longer carcasses at the same age at slaughter, but shorter carcasses when pigs were slaughtered at the same BW. This was also the case after feed restriction, for similar gain as in TRPdeficient animals. There was no effect of dietary TRP on muscle quality characteristics. The results were discussed in relation to the common stimulating effect of the limiting dietary factor for growth, whether amino acid or energy, on the development of the early maturing body compartments and the resulting changes in carcass conformation according to age or weight at slaughter. Keywords: Pig; Growth; Tryptophan; Experimental period; Feed intake; Body composition

1. Introduction Dietary tryptophan (TRP) deficiency in growing pigs is known to severely depress voluntary feed intake and performance (Henry and Pastuszewska, 1976; Montgomery et al., 1978, 1980; Leibholz, 1980; Henry et al., 1986; Sato et al., 1987; Sbve et al., 1991; Fremaut and Deschrijver, 1993; Lenis et al., 1990; Cortamira et al., 1991; Burgoon et al., 1992; Henry et al., 1992b; Han et al., 1993). This specific influence of TRP on * Corresponding author: Tel 33 9928 5039; Fax 33 9928 5080 0301-6226/95/$09.50

0 1995 Elsevier Science B.V. All rights reserved

X%X0301-6226(94)00045-9

feed consumption has been ascribed to its key role as a precursor of serotonin, one of the neurotransmitters involved in the central regulation of feed intake (Henry et al., 1992b). Besides depressed feed intake and growth performance, the effects of dietary TRP deficiency on body composition, carcass conformation and meat quality characteristics, namely muscle pH, are less conclusive. Due to a simultaneous decrease in lean and fat deposition, TRP deficiency seems to exert moderate effect on carcass composition, while carcass length is increased at a given slaughter weight (Henry et al.,

64

Y. Henry/Livestock Production Science 41(1995) 63-76

1992b). Muscle pH, measured either 45 min or 24 h postmortem, has been reported to increase in the case of deficiency (Henry et al., 1992b), or following dietary overload in relation to stress alleviation (Adeola et Ball, 1992; Henry and S&e, 1993). In fact, these effects may depend on age or weight at slaughter, or on growth pattern, and this is particularly the case for body composition and conformation (body length, regional development), in relation to the differential growth of body tissues and compartments (McMeekan, 1940a,b,c; PUsson and Vergks, 1952a,b; Davies, 1974a,b; Fowler, 1980). Considering that in most nutritional studies pigs are slaughtered at a fixed weight, there is a need for a good appraisal of the respective contributions of age and weight at slaughter to changes in body composition and conformation, or in meat quality, in response to dietary changes in TRP supply *

Table 1 Composition of basal diet Ingredient

%

Maize” Peanut mealb Beet molasses Dicalcium phosphate Limestone Trace element mixture’ Vitamin& L-lysine. HCl’ L-threonine DL-methionine L-tryptophan’ Monosodium L-glutamate Glycine Maize starch

79.5 10 3 1.4 1.5 0.10 0.115 0.44 0.08 0.03

Total

100

2.7 0.53 0.605

Yontained 87.7% DM, 8.5% CP. bContained 89.8% DM, 40.8% CP, 4.8% CF. Aflatoxin contents were 36ppbforBLand5ppbforB2. cIncluding, in mg/kg feed: zinc sulphate, 350; iron sulphate,220; manganese sulphate,50; copper sulphate, 20; potassium iodite, 0.8; sodium selenite, 0.4; cobalt sulphate, 0.4; limestone, 358.4. dAmounts/kgdiet: vitaminA,50001U;vitaminD3,1000UI;vi~~n E, 10 Ul; vitamin K3,2 mg; thiamin, 1 mg; IkflaVin, 4 IQ3 nicdnic acid, 15 mg; calcium pantothenate, 10 mg, pyridoxin, 1 mg;Vitamin Bl2,20 pg; folic acid, 1 mg; biotin, 0.02 mg; choline, 500 mg. “Contained 78% lysine base. ‘0.03% in the Control diet at the expense of maize starch.

Therefore, the objective of the present study was to analyze the effects of dietary TRP deficiency on feed intake, growth performance, carcass composition and conformation, and meat quality, in finishing pigs when slaughtered at the same age or live weight, or after a given live weight gain. By the same time, TRP, as the limiting amino acid, served as a nutritional factor to check the eventual interaction with the experimental period (whether age or weight interval) in altering body composition and conformation.

2. Material and Methods Three experiments were conducted with a total of 188 finishing pigs of the Large White breed within an average live weight range of 53 to 88 kg. After a one to two-week pre-experimental period, during which they were given a standard grower diet (17% CP, 0.85% lysine, 13.2 MJ DE/kg) according to a feeding scale corresponding to 125 g/kg body weight ( BW)“.75,the pigs were assigned to experimental treatments, within randomized blocks based on sex, initial weight and age. In the three experiments, a basal maizepeanut meal diet containing around 13.5% CP and 0.10% TRP was used (Table 1). The same batches of ingredients were utilized, with separate feed mixing for each experiment. Peanut meal was checked for its low contamination by aflatoxin: 36 and 5 ppb of Bl and Table 2 Feeding scale Live weight range (kg)

Amount of feed (kg/d)

24-28 28-32 32-36 36-40 40-44 44-48 48-52 52-56 56-60 60-64 64-68 68-72 72-80 80-90 90-100

1.4 1.6 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0

Y. Henry/Livestock Production Science 41 (1995) 63-76

Table 3 Chemical composition of experimental diets’

65

Gain (g/d) 10001

Experiment

1

Treatment

1

28~3

l&4

28~3

Dry matter (%) CP (a) Ash (%) Tryptophan ( % )

86.1 14.0 4.9 0.13

86.0 13.4 4.7 0.10

87.1 13.4 5.1 0.13

87.5 13.3 5.3 0.10

2&3

Feed intake (kg/d)

31 “Analyzed amino acid contents (%): lysine, 0.80; threonine, 0.48; methionine, 0.23; cystine, 0.24; methionine + cystine, 0.47. The analyzed tryptophan content in the basal diet was 0.10%. True deal amino acid contents (%) in the basal diet, calculated from RhGne Poulenc Animal Nutrition (1993) tables, were the following: tryptophan, 0.09; lysine, 0.72; threonine, 0.42; methionine, 0.22; methionine + cystine, 0.4 I. The content of true digestible tryptophan in the supplemented diet was 0.12%.

2.5. 21.5. l0.5. Oo,35 ,Gain/Feed

1 Treatment Tryptophan (%) 0.13 100 kg Slaughter 3 ,Feed intake (kg/d) lFemales

2 0.10 Same age

3 0.10 100 kg

4 0.13 Same age restricted

0Caswated males

Fig, 2. Differential response of feed intake and growth performance to dietary tryptophan deficiency, according to sex (Exp. 2).

o,3 Gain/Feed 0.25. 0.2. 0.15. 0.1 1 0.05 OTreatment 1 Ttyptophan, % 0.13 Slaughter 100 kg lFemalas

2 0.10 100 kg

3 0.10 100 kg

OCasbated males

Fig. I. Interactions between tryptophan and sex on feed intake and growth performance, according to age or weight at slaughter (Exp. 1).

B2, respectively. In each experiment, the pigs were fed according to a feeding scale on live weight basis, the same for females and castrated males (Table 2) , In Exp. 1, 60 pigs averaging 58.1 kg initial weight at 122 d were allotted to three treatments, with 10 replicates of females and castrated males in each. In the control treatment 1, the animals were fed the maizepeanut meal diet containing 14.0% CP and 0.13% TRP, with 0.03% addition of L-hyptophan to the basal diet. In treatments 2 and 3, the pigs were fed the same basal diet containing 0.10% TRP, and were slaughtered at the same weight ( 100 kg) or age within blocks, respectively, as in treatment 1. In Exp. 2, 80 pigs weighing initially 49.4 kg on average at 109 d of age were assigned to four treatments each including 10 females and 10 castrated males. The first three treatments ( 1, 2 and 3) were the same as in

66

Y. Henry/ Livestock Production Science 41 (199s) 63-76

Exp. 1, while in treatment 4 the pigs were fed the

Exp. 2, with 12 animals in each. Due to feed refusal in TRP-deficient pigs, it was decided to shorten the duration of the experiment, so that animals within blocks were slaughtered on the same day. Consequently, treatments 2 and 3 were regrouped in the same treatment. The animals were housed in a closed building and raised in individual pens (0.90 X 2.70 m) with straw

control diet (0.13% TRP) in restricted amount, in order that their growth curve be similar to those in treatment 2 within each block. They were slaughtered on the same day as pigs of treatments 1 and 2. In Exp. 3, 48 female pigs averaging 51.8 kg at 116 d of age were allotted to the same four treatments as in Table 4 Effects of dietary level of tryptophan,

according to age or weight at slaughter or body weight gain, on feed intake and growth performance”

Treatment

Tryptophan Slaughter

(%)

Experiment 1 Initial BW (kg) Final BW (kg) Duration (d) Daily gain (g/d) Daily feedd kg/d g/kg BW’.” Gain/feed Experiment 2 Initial BW (kg) Final BW (kg) Duration (d) Daily gain (g/d) Daily feedd kg/d g/kg BW0.‘” Gain/feed Experiment 3 Initial BW (kg) Final BW (kg) Duration (d) Gain (g/d) Daily feedd k/d g/kg BW075 Gain/feed

1 0.13 Control

58.1 99.5 55.0 756 2.12 103.3 0.278

49.3 100.9 69.4 750 2.42 95.3 0.309

51.3 84.0 50.9 620 2.23 94.2 0.275

Sex 2 0.10 Same age

3 0.10 Same wt

58.2 91.3 55.3 660

57.9 97.8 64.2 636

2.50 98.3 0.239

49.4 78.7 69.4 422 1.76 11.4 0.232

51.5 12.9 50.9 407 1.84 82.6 0.216

4 0.13 Same

1.98 80.7 0.258

F

MC

SEb

Sex

Trp age

Trp wt

57.5 95.3 60.9 633

58.6 97.0 55.4 695

1.1* 5.4* 8.0* 18.7

0.0052

0.0001

0.0001

0.0007 0.0083 0.100

0.0001 0.0065 0.0001

o.cO93 0.015 0.0001

0.0056

0.0001

0.0001

0.015

0.0001 0.0019 0.097

0.0001 0.0001 0.0001

0.0001 0.0001 0.0001

0.0001

Trp restr

age restr

2.58 98.9 0.245

49.2 98.0 96.6 533

Contrast P-value’

2.53 91.1 0.248

49.5 83.7 69.4 496 1.78 76.6 0.278

51.2 16.1 50.9 502 1.85 81.8 0.270

49.6 88.6 80.0 506 1.86 78.1 0.263

51.3 77.9 50.9 510 1.91 86.2 0.254

2.68 102.2 0.259

49.2 91.6 72.3 593 2.11 86.9 0.217

0.036 1.2 0.0053

0.74* 5.3* I.? 20.6 0.0031 1.7 0.0057

1.2* 6.1* 33.4

0.0001

0.069 2.3 0.011

0.0001 0.0003 0.0001

0.094 0.0094

“20 pigs per treatment ( 10 females: F; 10 castrated males: MC) in Exp. 1 and 2; 10 females per treatment in Exp. 3 (treatments 2 and 3 regrouped). bStandard error of the mean. The values with asterisk are standard deviations. TreatmentX sex interaction for all criteria (P< 0.10) in Exp. 1; no treatment sex X interaction in Exp. 2. ?p age: effect of TRP at the same age (Treatment 1 vs. 2); Trp wt: effect of TRP at the same BW (Treatment 1 vs. 3); trp restr: effect of TRP in pair-fed animals within blocks (Treatment 2 vs. 4). dThe metabolic weight was calculated according to Foster et al. ( 1983) and De Haer et al. ( 1993), assuming a linear increase in weight between start and end of trial: Bw75 (kg) = (BW:~7*-BWf~75)/1.75*(BWI_BWI), with BW, and BWrmeasured at the beginning and the end of the test period, respectively.

Y. Henry/Livestock

Production Science 41 (1995) 63-76

bedding. They were fed pelleted diets (4.5 mm in diameter) and had free access to water. Pig weights and feed intake were recorded on a weekly basis during the trials. After slaughter following an overnight fast, linear measurements of fat and lean were made on hot carcasses with a Fat-0-Meater (FOM: SFK, Hvidovre, Denmark). After 24 h chilling, half-carcasses were fractionated according to the French cutting procedure (Ollivier, 1970). Muscle and fat gains, in Exp. 1 and 2, were determined from the final amounts at slaughter

67

derived from the carcass evaluation procedure (Desmoulin et al., 1988) and the initial amounts of both tissues that were estimated by using prediction equations for Large White pigs of both sexes from the same experimental herd (Karege, 1991). In Exp. 3, muscle and fat contents in the carcass were estimated from FOM measurements, using the prediction equations of Desmoulin et al. ( 1988). Muscle pH was measured 45 min and 24 h postmortern on the freshly cut cross-sectional surface of Adduc-

Table 5 Effects of dietary level of tryptophan, according to age or weight at slaughter, on carcass characteristics (Exp. 1)”

Tryptophan (%) Slaughter

1 0.13 100 kg

Contrast P-value’

Sex

Treatment 2 0.10 Same

3 0.10 1OOkg

MC

F

SEb

Trp age

Trp wt

0.027

-

0.032

0.033 0.025

0.050 0.066

Sex

Age Hot carcass wt (kg) Dressing percentage Carcass length (cm)d total side Backfat thickness (mm)e X1 x2 x4 Muscle thickness X’5 (mm)‘ Cut weights (kg) : Half-carcass Head Feet Kidney fat Loin Ham Backfat Foreflank Belly Loinibackfat

82.5 82.9

14.9 81.9

82.3 83.2

79.7 82.9

80.1 82.5

4.0* 0.31

103.6 84.5

101.7 82.7

105.3 86.0

104.2 84.9

102.9 83.9

0.61 0.53

21.6 28.6 24.4

20.0 26.2 22.6

20.9 26.7 22.5

20.0 25.8 22.0

21.7 28.5 24.3

0.83 0.92 0.75

0.018 0.051

0.070 0.078

0.067 -

50.5

51.1

54.3

53.5

50.4

1.54

0.045

_

0.098

37.9 5.07 1.12 0.770

34.5 4.69

37.7 5.19 I.12 0.766 11.75 8.41 4.91 6.15 4.13 2.45

36.7 5.08

36.7 4.88

0.43 0.054 0.018 0.043 0.13 0.092 0.18 0.071 0.11 0.10

0.0036

0.0001 0.000 1

_

0.0001

-

0.000 1 0.0001

_

0.011 0.0001 0.0013

-

11.64 8.42 5.11 6.20 4.24 2.33

I .oo 0.690 10.76 7.64 4.45 5.70 3.69 2.52

1.07

1.09

0.698 11.49 8.20 4.59 5.98 4.13 2.60

0.786 11.28 8.11 5.06 6.05 3.90 2.27

0.025 0.0053 0.0073

_

‘20 pigs per treatment ( 10 females: F; 10 castrated males: MC). “Standard error of the mean. The value with asterisk is standard deviation. Treatment X sex interaction for head (P < 0.01). feet (P < 0.10). ham (P
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Production Science 41(1995)

Y. Henry/Livestock

tor femoris (AF), Semimembranosus (SM) and Longissimus (L) muscles by using a pH meter probe. The reflectance in L muscle at 630 nm was measured 24 h postmortem using a Retrolux reflectometer. Water retention capacity was also measured in L muscle after chilling, according to the method described by Goutefongea ( 1963). Proximate analyses of experimental feeds were conducted on aliquot samples during the trials according to AOAC ( 1984) procedures. Amino acid analysis by ion-exchange chromatography was performed on experimental diets. Sulphur amino acids were determined after performic oxidation. TRP content was measured in the basal diet after alkaline hydrolysis with

63-76

barium hydroxide. The estimated energy value of the diets was 13.6 MJ DE/kg on fresh basis, from JNRA (1989) tables. The composition of experimental diets is reported in Table 3. Statistical treatment of experimental data was performed with the GLM procedure of SAS ( 1990). After taking into account block effect nested within sex (split-plot design), sex effect in Exp. 1 and 2 was tested against the mean square of the residual between blocks. Treatment contrasts were tested against the mean square of the residual within block variation. Differences among comparisons were judged to be statistitally significant when associatedP-values were < 0.10.

Table 6 Effects of dietary level of tryptophan, according to age or weight at slaughter or body weight gain, on carcass characteristics (Exp. 2)” Treatment

Tryptophan (% ) Slaughter

Carcass wt (kg)

Dressing % Backfat ( mm)d Xl x2 x4 Muscle thickness X’5 (mm)’

I 0.13 1OOkg

Sex 2 0.10 Same age

3 0.10 1OOkg

83.4 82.1

62.1 19.1

21.0 26.0 22.3

Contrast P-value’

4 0.13 Same age restr

F

80.0 81.2

68.8 82.2

12.1 81.3

14.8 81.6

4.1* 0.31

15.2 20.9 19.5

18.6 26.4 23.1

16.1 21.7 18.7

16.5 21.9 19.4

18.9 25.5 22.4

0.91 0.94 0.78

51.6

46.6

51.0

46.1

49.0

49.0

1.9

5.14 38.0 1.13 0.661 12.45 8.50 4.78 6.15 4.01 2.68

4.36 28.2 0.96 0.468 9.03 6.36 3.26 4.68 2.81 3.03

5.29 36.1 1.15 0.804 11.73 8.08 4.54 5.10 3.61 2.73

4.67 30.9 1.00 0.487 10.31

4.92 32.1 1.06 0.538 10.51 1.41 3.63 5.31 3.31 3.20

4.81 33.9 1.06 0.675 10.85 1.62 4.33 5.55 3.51 2.63

0.065 0.51 0.018 0.038 0.27 0.11 0.17 0.088 0.099 0.17

MC

SEb

Sex

0.101 0.005 1 0.015

age

Trp

Trp wt

Trp restr

0.0001

0.022

0.0001

0.0091 0.0003 0.015

Cut weights (kg):

Head Half-carcass Feet Kidney fat Loin Ham Backfat Foreflank Belly Loin/backfat

1%

3.34 5.18 3.15 3.22

0.0063 0.071

0.0011 0.0001 0.0002 0.020

0.0098

“20 pigs per treatment (10 females: F; 10 castrated males: MC). bStandard error of the mean. The values with asterisk are standard deviations. Treatment x sex interaction for kidney fat (P < 0.01) and loin (P
Y. Henry /Livestock Production Science 41(1995) 63-76

3. Results 3.1. Feed intake and growth peeormance

Only 10 blocks completed Exp. 3. In addition, due to the difficulty to keep the pigs on the TRP-deficient diet for a prolonged period, the pigs in treatments 2 and 3 were slaughtered at the same age, so that the mean results are given for the two groups. In Exp. 2 and 3, pigs of treatment 4 were intended to have similar weight gain within blocks as those of treatment 2. In fact, the level of feeding was the same in both treatments with different growth performance (76 and 77 g/kg Bw75 in treatments 2 and 4, respectively, in Exp. 2, 83 and 82, respectively, in Exp. 3). Therefore, covariance analysis with live weight gain as the covariate was conducted in these two treatments 2 and 4, to test the effect of supplementary TRP for similar weight gain. The reduction of dietary TRP from 0.13 to 0.10% depressed growth rate, feed intake and feed efficiency,

69

whether the pigs were slaughtered at the same age or weight, but with less pronounced difference when pigs were slaughtered at the same BW (Table 4). On the whole, sex interacted with TBP level, with higher depressive effect in females than in castrated males (Fig. 1 and 2). In pair-fed pigs (Treatments 2 and 4 in Exp. 2 and 3)) TFtP deficiency also depressed daily gain and feed efficiency. This depressive effect on feed efficiency was maintained after covariance analysis on live weight gain (0.252 vs. 0.279 in treatments 2 and 4 of Exp. 2, respectively, P
Table 7 Effects of dietary level of tryptophan, according to age or weight at slaughter or live weight gain, on carcass characteristics (Exp. 3)” Treatment

1 Tryptophan (%) Slaughter

Hot carcass wt (kg) Dressing percentage Carcass length ( cm)d total side Backfat thickness (mm)’ Xl x2 x4 Muscle thickness’ X’5 (mm)

0.13 84 kg

Contrast P-value’ 2&3 0.10 Same age

4 0.13 Same age Restricted

SEb

Trp age

70.2 83.3

60.0 82.2

63.5 82.8

5.9* 0.54

0.109

100.8 83.1

98.4 80.7

100.7 82.3

0.86 0.79

0.031 0.021

19.1 24.7 20.4

13.5 19.9 17.4

13.5 18.6 16.8

1.2 1.2 1.0

0.0006 0.0027 0.019

49.5

44.5

45.3

2.1

0.063

Trp mstr

0.060

0.023 0.099

“10 female pigs per treatment; treatments 2 and 3 regrouped. bStandard error of the mean. The values with asterisk are standard deviations. ‘Trp age: effect of TRP at the same age (Treatment 1 vs. 2 & 3) ; Trp restr: effect of TRP in pair-fed animals within blocks (Treatment 2 vs. 4). dTotal carcass length between the atlas and the.anterior edge of pubic symphysis; side length between the middle of the first rib and the anterior edge of pubic symphysis. After covariance analysis with BW gain as a covariate in treatments 2 and 4 within blocks, the adjusted values for total carcass length were 98.1 and 100.9, respectively (P < 0.10). ‘Xl, on the midline; X2, between the 3rd and 4th lombar vertebras, 8 cm from the midline; X4, between the 3rd and 4th ribs, 6 cm from the midline. ‘At the same site as X4, between the 3rd and 4th ribs, 6 cm from the midline.

Y. Henry /Livestock Production Science 41 (1995) 63-76

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Table 8 Effects of dietarylevel of tryptophan, according to age or weight at slaughter or body weight gain, on carcass muscle and fat contents and gains” Treatment

Sex

Tryptophan (%) Slaughter

1 0.13 Control

2 0.10 Same age

3 0.10 Same wt

Experiment 1 Muscle (%)d Fat ( %)d Muscle wt ( kg)e Fat wt (kg)’ Muscle gain (g/d) Fat gain (g/d)

48.9 28.5 36.92 21.54 230 198

49.8 26.9 34.01 18.55 172 145

49.6 27.6 37.31 20.72 201 162

Experiment 2 Muscle (%)d Fat ( %)d Muscle wt ( kg)e Fat wt (kg)” Muscle gain (g/d) Fat gain (g/d)

51.9 26.3 39.58 20.07 275 173

52.0 23.0 29.31 13.36 122 75

51.8 26.5 37.88 19.44 181 125

Experiment 3 Muscle %’ Fat %d Muscle wt (kg) Fat wt (kg) Muscle gain (g/d) Fat gain (g/d)

49.9 25.5 31.41 16.46 170 139

50.8 21.9 26.70 11.93 80 52

4 0.13 Same age restr

Contrast P-value”

F

MC

SEb

Sex

50.1 26.6 36.39 19.47 190 154

48.8 28.7 35.77 21.11 212 183

0.66 0.81 0.48 0.74 9.5 13.0

0.045 0.030

54.6 22.5 34.06 14.10 193 84

53.6 22.8 33.36 15.44 179 90

51.5 26.3 34.90 18.17 206 139

1.3 0.8 0.76 0.71 12.1 10.3

51.8 21.2 29.25 12.05 139 63

50.8 22.9 29.12 13.43 130 85

0.62 0.90 0.81 0.93 15.2 16.0

0.053 0.025 0.047

0.0043 0.0096 0.072 0.0035

Trp age

Trp wt

0.0001 0.0073 0.0001 0.0062

0.040 0.072

-

-

0.0051 0.0001 0.0001 0.0001 0.0001

0.0001 0.001

0.0029 0.0001 0.0004 0.0001 0.0001

Trp restr

0.0001 0.0001

0.020 0.046

0.045

“20 pigs per treatment (10 females: F; 10 castrated males: MC) in Exp. 1 and 2; 10 female pigs per treatment in Exp. 2 (treatments 2 and 3 regrouped). ?Standard error of the mean. ‘Trp age: effect of TRP at the same age (Treatment 1 vs. 2) ; Trp wt: effect of TRP at the same BW (Treatment 1 vs. 3) ; trp restr: effect of TRP in pair-fed animals within blocks (Treatment 2 vs. 4). din cold carcass without head. ‘Muscle and fat weights were calculated in Exp. 1 and 2 after estimating cold carcass weight with head from warm carcass weight with head, using the following equation obtained on pigs of the same breed in similar conditions: Cold carcass weight with head (kg) = 0.9762* Hot carcass weight with head (kg) - 0.4238 (n = 413, R* = 0.990). In Exp. 3, they were calculated from Cold carcass without head (kg) = 1.0053* Hot carcass weight with head (kg) -7.4017 (n=417, R*=0.971).

to a more depressive effect of TRP deficiency in females than in castrated males at the same age at slaughter. This greater depressive effect in females was also observed in Exp. 2 for kidney fat and loin. Dressing percentage decreased with TRP deficiency at the same final age (Treatment 2), in the three experiments. This was also the case at the same final BW (Treatment 3) in Exp. 2, but no difference occurred in Exp. 1. In pair-fed animals (Exp. 2: Treatments 2 and 4), there was also a decrease in dressing percentage following TRP deficiency.

The effect of dietary TRP on carcass length depended on age or weight at slaughter. Compared to controls, total or side carcass length decreased in TRP-deficient pigs on slaughter age basis ( - 1.8% in Exp. 1 and - 2.4% in Exp. 3)) along with lowered weight of loin ( - 7.6% in Exp. 1) , but increased on slaughter weight basis ( + 1.6% in Exp. 1) for the same weight of loin. In pair-fed animals (Exp. 3: treatments 2 and 4), TRP deficiency decreased total carcass length, that was still decreased after covariance analysis on weight gain in these two treatments ( 100.9 in Treatment 4 vs. 98.1 in

Y. Henry/Livestock Production Science 41 (1995) 63-76

71

Table 9 Effects of dietary level of tryptophan, capacity”

according

to age or weight at slaughter or body weight gain, on muscle pH, colour and water retention

Treatment 1 0.13 Control

TRP (%) Slaughter

sex 2 0.10 Same age

Experiment 1 pH 45 min postmortem Semimembranosus Adductor Longissimus pH 24 h postmortem Semimembranosus Adductor Longissimus ColouP Water retention” Experiment 2 pH 45 min postmortem Semimembranosus Adductor Longissimus pH 24 h postmortem Semimembranosus Adductor Longissimus Colour Water retention (%) Experiment 3 pH 45 min postmortem Semimembranosus Adductor Longissimus pH 24 h postmortem Semimembranosus Adductor Longissimus “20 pigs per treatment

6.22 6.02 6.16

6.23 6.12 6.0 1

3 0.10 Same wt

4 0.13 Same

F

Contrast P-value’

MC

SEb

age restr

6.26 6.12 6.03

6.29 6.11 6.12

6.18 6.05 6.01

0.057 0.062 0.063

5.70 5.81 5.61 70.6 72.7

5.72 5.83 5.57 74.6 72.8

0.038 0.053 0.030 3.2 0.8

5.70 5.84 5.61 73.3 73.0

5.74 5.83 5.59 71.0 73.0

5.70 5.79 5.58 73.6 72.7

6.24 6.10 6.06

6.18 6.04 6.03

6.25 6.11 6.21

6.14 6.01 6.15

6.20 6.06 6.14

5.71 5.84 5.67 78.1 72.7

5.70 5.78 5.62 74.6 72.3

5.65 5.73 5.61 72.9 72.4

5.66 5.72 5.63 77.2 72.9

5.66 5.73 5.61 74.3 73.2

6.13 6.11 6.17

6.12 6.05 6.15

6.15 6.10 6.33

6.13 6.09 6.22

0.083 0.072 0.106

5.71 5.87 5.64

5.75 5.82 5.64

5.72 5.81 5.72

5.73 5.83 5.67

0.040 0.073 0.048

(10 females: F; 10 castrated males: MC) in Exp.

regrouped). “Standard error of the mean. Trp age: effect of TRP at the same age (Treatment pair-fed animals within blocks (Treatment

6.2 1 6.07 6.09 5.70 5.80 5.66 77.2 72.7

Sex

Trp age

Trp wt

0.066 0.0061 0.071 0.028 0.046 0.025 2.0 0.64

1 and 2; 10 female pigs per treatment in Exp. 3 (treatments 2 and 3

1 vs.2); Trp wt: effect of TRP at the same BW (Treatment 1 vs. 3). No effect of TRP in

2 vs. 4).

Treatment 2; P < 0.10). Among FOM measurements, the effect of lowered TRP level was to decrease backfat thickness at Xl, X2 and X4 in pigs slaughtered at the same age as controls. When they were slaughtered at the same BW, the dif-

ferences were lower and only significant for X2 in Exp. 2 (P< 0.10). This decrease of backfat thickness with TRP deficiency did not generally occur in pair-fed pigs: X2 and X4 measurements were even greater in Exp. 3 (P< 0.05 and P < 0.10, respectively). In Exp. 2 and 3,

12

Y. Henry/Livestock Production Science 41 (1995) 63-76

muscle depth (X’5) decreased in TRP-deficient pigs, when they were slaughtered at the same age as controls (P < 0.10)) but it increased when pigs in Exp. 1 were slaughtered at the same weight (P < 0.10). The weights of carcass joints (Table 5, 6 and 7) were generally lowered in TRP-deficient animals at the same age (Treatment 2) compared to controls (Treatment 1). They were unchanged in pigs slaughtered at the same BW, except for the weight of kidney fat in Exp. 2, that was higher in Treatment 3 (0.924 kg or 2.5% of carcass) than in Treatment 1 (0.591 kg or 1.6% of carcass) at P < 0.01, after data had been adjusted to the same half-carcass weight that slightly differed between treatments. When expressed in percentage of carcass, in pigs slaughtered at the same BW, it follows that the percentages of joints were not affected by TRP deficiency, with the exception of a higher value for kidney fat in Exp. 2. In TRP-deficient pigs slaughtered at the same age as the controls, only the proportion of belly in Exp. 1 was lower. In Exp. 2, the percentages in the carcass of pigs slaughtered at the same age were higher for head (7.0 vs. 6.2 %; P < 0.01) and feet (3.4 vs. 3.0%; P < 0.0 1) ; the percentages in half-carcass were lower for backfat ( 11.3 in Treatment 2 vs. 12.6 in Treatment 1; P < 0.05), and for foreflank (9.9 vs. 10.5%; P
(Table 8) shows a strong decrease in TRP-deficient animals slaughtered at the same age as controls, while they did not differ at the same slaughter weight. As a consequence, there was a small incidence of TRP deficiency on carcass tissue composition. Like average daily gain, daily gains of muscle and fat were depressed by TRP deficiency, whether the animals were slaughtered at the same age or at the same BW. Extending the duration of the trial to the same final BW (9 and 27 more days in Exp. 1 and 2, respectively) resulted in less severe growth and tissue gain depression than at the same age. In pair-fed animals (Exp. 2 and 3)) muscle and fat weights and gains were greatly depressed with TRP deficiency. After covariance analysis on live weight gain in Exp. 2, muscle weight (30.3 vs. 33.0 kg) and muscle gain (137 vs. 177 g/d) were still decreased (P < 0.10) . 3.4. Meat quality characteristics

Muscle pH values (45 min or 24 h postmortem) were not influenced by dietary TRP (Table 9), except for pH measured 45 min postmortem in Longissimus muscle in Exp. 1, which tended to decrease in TRPdeficient pigs slaughtered at the same age as controls (P < 0.10). No effect of dietary TRP was observed on muscle colour and water retention capacity. 4. Discussion 4.1. Eflects of tryptophan dejiciency on feed intake and growth peqormance The present results bring evidence of severe depression of appetite and growth performance in pigs when fed diet deficient in TRP, with only 0.10% in the finisher diet, and confirm our previous observations (S&e et al., 1991; Henry et al., 1992b; Henry, 1995). Furthermore, they corroborate the greater sensitivity of females to TRP deficiency in comparison with castrated males, as evidenced by sex X TRP interaction. This difference is at least partly explained by the greater amino acid requirements in females than in castrated males. As reported earlier (Henry et al., 1992b), this higher susceptibility of females to dietary TRP deficiency is aggravated in the presence of excess protein, in the form of large neutral amino acids, in relation to less potent

Y. Henry/Livestock Production Science 41(1995) 63-76

serotoninergic system than in castrated males. In addition to its specific effect on appetite, TRP, as the limiting amino acid, also exerts a positive influence on growth at a given level of feed intake, in accordance with its stimulation of body protein synthesis (Cortamira et al., 1991). By comparing the results of the experiments, the greater depressive effect of TRP deficiency on feed intake and growth performance in Exp. 2 and 3 was related to a lower initial live weight (49.4 and 51.3 kg on average, respectively) than in Exp. 1 (58 kg). On the other hand, the less pronounced effect of TRP deficiency on growth performance in older pigs slaughtered at the same BW as controls is due to decreased amino acid requirement with age, although female pigs continued to suffer more severely than castrated males from depressed appetite with advancing age. 4.2. Effects of dietary tryptophun on body composition and carcass conformation

While reducing feed intake and growth, dietary TRP deficiency impedes the development of both lean and fat tissues, in agreement with our previous results (Henry et al., 1992b; Henry, 1995). This explains that the final amounts of lean and fat cuts were lowered simultaneously when the pigs were slaughtered at the same age, and were similar to those in control animals at the same slaughter weight, thus indicating that in both cases lean/fat ratio (loin/backfat) was little affected by TRP deficiency. In contrast to this specific contribution of TRP deficiency, through depressed appetite, we have shown (Henry, 1995) that a sublimiting supply of other amino acids, either lysine or threonine, by increasing feed intake per unit of metabolic weight compared to control diet, along with lower gain, was associated to increased adiposity. In addition to overall carcass lean/fat ratio, the supply of TRP, as the limiting amino acid, may affect carcass conformation through changes in the anatomical distribution of tissues and lean primal cuts in the different body compartments. Thus, increasing the level of the limiting amino acid in the diet throughout fattening and under ad lib. feeding, either lysine (Henry et al., 1971; Henry et al., 1992a) or tryptophan (Henry et al., 1992b), has been shown to reduce carcass length at a given slaughter weight ( 100 kg). This is also the case in the present study when pigs were slaughtered

13

at the same weight (Treatment 1 vs. Treatment 3 in Exp. 1 and 2), while the weight of loin was the same. But, when slaughtered at the same age, TRP-supplemented pigs had longer carcasses (Exp. 1 and 3)) with increased weight of loin. Interestingly, when the data of Exp. 2 were adjusted to the same weight gain, either in TRP-adequate diet (0.13%: Treatment 4) or at deficient level (0.10%: Treatment 2)) the only increase in cut weights was observed for ham and belly; by the same time, in Exp. 3, total carcass length was increased. In other words, for a given BW gain, additional TRP favored the development of early maturing parts of the body (hindquarter and forequarter), as well as carcass length. This stimulating effect of the limiting amino acid on the growth of early maturing regions (ham and belly) has also been reported previously in the case of lysine (Henry et al., 197 1). We may then conclude that the addition of a limiting amino acid (tryptophan or lysine) to the diet exerts a positive effect on the development both in depth and length, but with a greater contribution of the early maturing parts (ham and belly), thus resulting in longer carcasses at a given age and shorter carcasses at a given BW. This stimulating effect of the limiting amino acid may be extended more generally to the limiting factor for growth, since dietary energy restriction has also been reported to decrease carcass length at a given slaughter weight (Bourdon and Henry, 1991)) thus confirming the general influence of nutrient supply on the differential growth of body tissues and compartments (McMeekan, 1940a,b,c; P&son and Verges, 1952a,b; Fowler, 1980). Furthermore, in restricted feeding, either lysine supplementation (Bourdon and Henry, 1991) or additional tryptophan (present study, treatments 2 and 4 in Exp. 3), as the limiting amino acid, induces a further increase in carcass length when pigs are slaughtered at the same weight. 4.3. Dietary tryptophan and meat quality In a previous study (Henry et al., 1992b), we reported an increase in muscle pH both 45 min and 24 h postmortem with decreased TRP supply, especially in females as opposed to castrated males. No explanation could be provided for this difference, since dietary TRP overload before slaughter, by alleviating stress conditions, has also been reported by Adeola and Ball ( 1992) to decrease the incidence and severity of PSE

14

Y. Henry/Livestock Production Science 41 (1995) 63-76

ham and loin. In a further investigation (Henry and S&e, 1993)) after large variation of dietary TRP level from deficiency to oversupply, it appeared that the ultimate muscle pH was the lowest at the level corresponding to optimum growth. On the opposite, the results of the present experiments do not show any evidence of an effect of dietary TRP deficiency on muscle pH, as well as on other meat quality traits (colour, water retention capacity), although the experimental plan allowed to take into account the eventual bias due to slaughter conditions (Eikelenboom and Hoving-Bolink, 1993), by measuring pH on the same day within blocks. It is worth noting that pH measurement at 45 min postmortem was made directly on the cut. The resulting greater variability than from results obtained with an homogenate (Henry et al., 1992b) may have masked part of postmortem changes in pH. Nevertheless, due to the high number of observations, it is unlikely that dietary TRP, in our experimental conditions, had some effect on muscle quality characteristics. To conclude, in addition to its specific effect on feed intake, dietary supply of tryptophan, in growing-finishing pigs, by stimulating the development of early maturing body compartments (forehand and hindquarter) , may affect differently growth performance, and carcass composition and conformation, depending on age or weight at slaughter. Further investigations are needed to explore the interrelationships between dietary supply of the limiting factor for growth, either amino acid or energy, and production potential (genotype), on growth allometry, and the resulting consequences on carcass composition and conformation, in relation to the ultimate incidence on commercial returns. in

Acknowledgements The author gratefully acknowledges the technical assistance of G. Conseil, M. Lemarie and associates for conducting the experiments, L. Jaffrennou and associates for carcass evaluation, P. Ecolan for meat quality measurements, N. MCzibre for feed analyses, and Y. Colleaux for amino acid analysis. He extends his appreciation to DEGUSSA laboratory, Hanau-Wolfgang (Germany), for analyzing tryptophan in the basal diet.

References Adeola, 0. and Ball, R.O., 1992. Hypothalamic neurotransmitter concentrations and meat quality in stressed pigs offered excess dietary tryptophan and tyrosine. J. Anim. Sci., 70: 1888-1894. AOAC, 1984. Official methods of analysis (14th Ed.). Association of Official Analytical Chemists, Arlington, VA. Bourdon, D. and Henry, Y., 1991. Reponse du port en finition a la supplementation du regime en lysine, en fonction du niveau de rationnement et selon le sexe. Joum. Rech. Porcine Fr., 23: 11l118. Burgoon, KG., Knabe, D.A. and Gregg, E.J., 1992. Digestible tryptophan requirements of starting, growing and finishing pigs. J. Anim. Sci., 70: 2493-2500. Cortamira, N.O., S&e, B., Lebreton, Y. and Gamer, P., 1991. Effect of dietary tryptophan on muscle, liver and whole-body protein synthesis in weaned piglets: relationship to plasma insulin. Brit. J. Nutr., 66: 423-435. Davies, AS., 1974a. A comparison of tissue development in Pi&rain and Large White pigs from birth to 64 kg live weight. 1. Growth changes in carcass composition. Anim. Prod., 19: 367-376. Davies, AS., 1974b. A comparison of tissue development in Pi&rain and Large White pigs from birth to 64 kg live weight. 2. Growth changes in muscle distribution. Anim. Prod., 19: 377-387. De Haer, L.C.M., Luiting, P. and Aarts, H.L.M., 1993. Relations among individual (residual) feed intake, growth performance and feed intake pattern of growing pigs in group housing. Livest. Prod. Sci., 36: 233-253. Desmoulin, B., Ecolan, P. and Bonneau, M., 1988. Estimation de la composition tissulaire des carcasses de ports: mcapitulatif de diverses methodes utilisables en experimentation. Prod. Anim., 1: 59-64. Eikelenboom. G. and Hoving-Bolink, R., 1993. Einfliisse der Futterzusammensetzung, des Geschlechts und des Zeitpunkts der Schlachtung. Fleischwirtsch., 73: 648-650. Foster, W.H., Kilpatrik, D.J. and Heaney, I.H., 1983. Genetic variation in the efficiency of energy utilization by the fattening pig. Anim. Prod., 37: 387-393. Fowler, V.R., 1980. Growth in mammals for meat production. In: T.L.J. Lawrence (Ed), Growth in Animals. Butterworths, London, p. 249-263. Fremaut, D. and Deschrijver, R., 1990. Tryptophan supplementation of diets for growing-finishing pigs. Revue de I’Agriculture 43: 761-768. Goutefongea, R., 1963. Comparaisons de diffkrentes m&hodes de mesure du pouvoir de retention d’eau de la viande de port. Liaison avec Ie pH. Ann. Zootech., 12: 125-132. Han, Y., Chung, T.K. and Baker, D.H., 1993. Tryptophan requirement of pigs in the weight category 10 to 20 kilograms. J. Anim. Sci., 70: 139-143. Henry, Y., 1995. Influence dun deficit ou d’un desequilibre alimenmire en acides amines pendant une phase initiale de la croissance sur les performances du port en finition. Ann. Zootech., 44: (In press). Henry, Y. and Pastuszewska, B., 1976. Consequences dune deficience du regime en tryptophane chez le port sur le niveau d’inges-

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tion et les performances de croissance. Ann. Zootech., 25: 143148. Henry, Y. and Seve, B., 1993. Prise en compte de l’exces alimentaire d’acides amin6s neutres pour la correction de I’bquilibre du tryptophane par rapport a la lysine chez le port en croissance. Joum. Rech. Porcine Fr., 25: 247-253. Henry, Y., Colltaux, Y. and S&e, B., 1992a. Effects of dietary level of lysine and of level and source of protein on feed intake, growth performance, and plasma amino acid pattern in the finishing pig. J. Anim. Sci., 70: 188-195. Henry, Y., R&at, A. and Tomassone, R., 1971. Etude du besoin en lysine du port en croissance-finition, Application de l’analyse multidimensionnelle. Ann. Zootech., 20: 521-550. Henry, Y., DuQ, P.H., R&at, A. and Pion, R., 1986. Determination of tryptophan requirement of growing pigs between 15 and 50 kg live weight. Nutr. Rep. Int., 34: 565-573. Henry, Y., Seve, B., Colleaux, Y., Gamer, P., Saligaut, C. and Jego, P., 1992b. Interactive effects of dietary levels of tryptophan and protein on voluntary feed intake and growth performance in pigs, in relation to plasma free amino acids and hypothalamic serotonin. J. Anim. Sci., 70: 1873-1887. INRA, 1989. L’alimentation des animaux monogastriques: port, lapin, volailles ( 2e edition). INRA, Paris, 282 pp. Karege, C., 1991. Influence de l’age et du sexe sur l’utilisation de l’bnergie et la composition corporelle chez le port en croissance. These Universite de Montpellier II, Sciences et techniques du Languedoc, 254 pp. Leibholz, J., 1981. Tryptophan requirements of pigs between 28 and 56 days of age. Aust. J. Agric. Res., 32: 845-850. Lenis, N.P., van Diepen, J.T.M. and Goedhart, P.W., 1990. Amino acid requirements for methionine-cystine, threonine and tryptophan of fast-growing boars and gilts, fed ad libitum. Neth. J. Agric. Sci., 38: 577-595. McMeekan, C.P., 194Oa.Growth and development in the pig, with special reference to carcass quality characters. I. General. J. Agr. Sci.30: 276348.

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McMeekan, C.P., 1940b. Growth and development in the pig, with special reference to carcass quality characters. II. The influence of the plane of nutrition on growth and development. J. Agr. Sci.. 30: 387-436. McMeekan, C.P., 1940~. Growth and development in the pig, with special reference to carcass quality characters. III. The effect of the plane of nutrition on the form and composition of bacon pig. J. Agr. Sci., 30: 51 l-569. Montgomery, G.W., Flux, D.S. and Carr, J.R., 1978. Feeding pattern in pigs: the effects of amino acid deficiency. Physiol. Behav., 20: 693-698. Montgomery, G.W., Flux, D.S. and Greenway, R.N., 1980. Tryptophan deficiency in pigs: changes in food intake and plasma levels of glucose, amino acids, insulin and growth hormone. Horm. Metab. Res., 12: 304. Ollivier, L., 1970. L’epreuve le la descendance chez le port Large White Fran& de 1953 a 1966. I. Analyse de variation. Ann. G&t. Stl. Anim., 3: 31 l-324. P&son, H. and Verges, J.B., 1952a.Effects of the plane of nutrition on growth and the development of carcass quality in lambs. I. The effects of high and low planes of nutrition at different ages. J. Agr. Sci., 42: l-92. P&son, H. and Verges, J.B., 1952b. Effects of the plane of nutrition on growth and the development of carcass quality in lambs. II. Effects on lambs of 30 lb carcass weight. J. Agr. Sci., 42: 93149. Rhdne Poulenc Animal Nutrition, 1993. RhodimetTM Nutrition Guide (2nd edition). Antony, France, 55 pp. SAS, 1990. SAS User’s Guide: Statistics. SAS Inst. Inc., Cary, NC. Sate, H. Kobayashi, T., Jones, R.W. and Easter, R.A., 1987. Tryptophan availability of some feedstuffs determined by pig growth assay. J. Anim. Sci., 64: 191-200. S&e, B., Meunier-Salatln. M.C., Monnier, M., Collbaux, Y. and Henry, Y., 1991. Impact of dietary tryptophan and behavioral type on growth performance and plasma amino acids of young pigs. J. Anim. Sci., 69: 3679-3688.

R&urn& Henry, Y., 1995. Influence d’un deficit alimentaire en tryptophane chez le port en finition, selon l’age ou le poids a l’abattage, ou le gain de poids vif. Liuest. Prod. Sci., 41: 63-76 (en anglais) Trois experiences ont et6 realis& sur un effectif total de 188 ports de race Large White (femelleset males castms), entre les poids vifs moyens de 53 et 88 kg, afin d’etudier I’influence d’une deficience alimentaim en tryptophane (TRP: 0,lO vs. 0.13%) sur l’ingestion d’aliment, les performances de croissance, la composition corporelle, les gains de tissus et la qualite de la viande, selon l’age ou le poids a l’abattage, ou pour un meme gain de poids vif, chez des animaux soumis a un rationnement alimentaire. Un deficit en TRP provoque un effet fortement depressif sur la consommation d’aliment, les performances de croissance et les depots de tissus (muscle et gras) , cet effet &ant moins prononce lorsque les ports sont abattus au meme poids. Le taux de TRP interagit avec le type sexuel, les femelles &ant plus sensibles que les males cast& a un deficit en cet acide amine. Les poids des morceaux de decoupe chez les animaux abattus au m&meage sont diminues, qu’il s’agisse des morceaux ma&es ou gras, mais ne different pas au meme poids a l’abattage. En consequence, un deficit en TRP ne modifie pratiquement pas la composition corporelle finale. La comparaison des moyennes ajustQs pour un &me gain de poids vif fait apparaii un developpement plus important des regions corporelles les plus pticoces (jambon, poitrine) sous l’effet du TRP supplementaire. Alors que les carcasses sont plus longues au meme age a I’abattage, le developpement pmferentiel en tpaisseur (parties posterieures et anterieures) avec l’addition de TRP favorise l’obtention de carcasses plus courtes au m&e poids a I’abattage. Les caracteristiques qualitatives des muscles (pH, couleur et retention d’eau) ne sont pas affect&es par le taux de TRP. Les r&ultats obtenus sont disc&s en relation avec l’effet stimulant du facteur limitant de la croissance sur le developpement des regions corporelles les plus pmcoces, suivant qu’il s’agit d’un acide amine (tryptophane, lysine) ou de I’apport d’energie, du point de vue des consequences sur la composition et la conformation des carcasses, selon Page ou le poids a l’abattage.

76

Y. Henry /Livestock Production Science 41 (1995) 63-76

Kurzfassung Y.‘Hemy, 1995. Wiikungen eines Tryptophamnangels im Putter von Mastschwemen je nach Alter oder Gewicht beim Schlachten oder Zunahme an kebendmasse. best. Prod. Sci., 41: 63-76 (auf englisch). Es wurden drei Versuche durchgeftihrt mit 188 Mastschweinen (Sauen und Kastraten) der Rasse Large White mit miffleren Kijrpennassen swischen 53 und 88 kg bei Ftittenmg nach Futtertabelle. Die Wirkungen eines Tryptophanmangels im Futter (0,lO gegentiber 0.13%) auf Futterverzehr, Mastleistung,KarperzusammensetzungundGewebszunahmesowieFleischquali~jenachAlterbzw. K&permassebeimSchlachten oder Zunahme an Karpermasse, Tryptophanmangel senkte den Futterverzehr, die Mastleistung und die Zunahme an Gewebe (Muskel und Fett) , wobei diese Wirkung mit fortschreitendem Alter geringer wurde. Sauen reagierten empfindlicher auf Tryptophanmangel als Barge. Die Gewichte der magemn wie such der fetten Stticke wamn nach Ttyptophanmangel niedriger in Schweinen, die bei gleichem Alter geschlachtet wurden, wobei kein Unterschied in der Schlachtk&perzusammensetzung resultierte. Dagegen waren sie gleich wie bei den Kontrolltieren nach Schlachtung bei gleicher Lebendmasse. Der Zusatz des limitierenden Tryptophans zum Futter beeinflu6te die Schlachtk&petbeschaffenheit vor allem durch Forderung der Tiefenentwicklung (Viertel) im Vergleich zur En&vi&lung der Cinge mit der Folge Ringerer Schlachtk&per nach Schlachtung bei gleichem Alter aber kttrzerer Schlachtk6rper nach Schlachtung bei gleichem Gewicht. Dasselbe trat auf, wenn nach mstriktiver Ftitterung Tiere mit gleicher Tageszunahme verglichen wurden. Keine Wiikung des Tryptophans auf Merkmale der MuskelqualiCit wurden festgestellt. Die Ergebnisse werden diskutiert in Beziehung auf gemeinsame stimulierende Wirkungen des jeweils limitierenden Futterfaktors auf das Wachstum, sei es eine Aminositure oder Energie, auf die Entwicklung frtthreifender KQerteile und die msultierenden Verilnderungen in der SchlachtkCkperbeschaffenheit je nach Alter oder Gewicht beim Schlachten.