The use of nutritional management after weaning for the production of heavier lamb carcasses from Greek dairy breeds

Livestock Production Science 57 (1999) 279–289

The use of nutritional management after weaning for the production of heavier lamb carcasses from Greek dairy breeds a a a b, a 1 ,a D. Zygoyiannis , N. Katsaounis , C. Stamataris , G. Arsenos *, L. Tsaras , J. Doney a

Department of Animal Husbandry, Faculty of Veterinary Medicine, Aristotle University, 54006 Thessaloniki, Macedonia, Greece b Animal Biology Division, Scottish Agricultural College, Bush Estate, Penicuik EH26 0 QE, Scotland, UK Received 27 February 1998; accepted 9 July 1998

Abstract The present study was conducted to investigate whether nutritional treatments can influence the carcass composition, potential consumer acceptability and cost of rearing, at any defined liveweight (LW) or proportion of breed mature weight (MW), in male lambs of three indigenous Greek dairy breeds of sheep. Two trials were carried out each with 30 weaned lambs (about 42 days) of the Boutsko (B), Serres (S) and Karagouniko (K) breeds. The lambs were reared under different conditions of diet, housing and management and were slaughtered at different degrees of maturity or different slaughter weights. During the first trial, the lambs were individually fed on three levels: high (H), medium (M) and low (L) of concentrate (192 g crude protein / kg DM and 11.3 MJ ME / kg DM) and Lucerne hay (182 g crude protein / kg DM and 8.3 MJ ME / kg DM) offered ad libitum. During the second trial, the lambs were group fed indoors for 63 days on three levels (also denoted as H, M and L) of the same concentrate and Lucerne hay ad libitum, and then finished on irrigated sown pasture (Lolium perenne 1 Trifolium repens). It was found that in both trials, breed of lambs and concentrate allowances (CA) had a significant effect (P , 0.001) both on daily LW gain (g) and time taken to reach the target LW. The proportion of fat in the carcasses of lambs was affected significantly by the breed and LW at slaughter of lambs (P , 0.001) and also by the CA (P , 0.01) in year 1 whereas in year 2 only LW at slaughter had a significant effect (P , 0.05). Lambs finished indoors were fatter than those finished on irrigated sown pasture. The results suggest that manipulation of post-weaning nutrition for the Greek dairy breeds, based on locally available feeds, can be used to produce consumer acceptable carcasses heavier than the traditional from suckled lambs and the marketing period can be extended to avoid the current oversupply at traditional marketing times. ´ ´ Resume ´ ´ ´ realisees ´ ´ afin d’estimer l’influence du type d’alimentation et de la race des agneaux sur la Deux experiences ont ete ´ necessaire ´ composition chimique de la carcasse et l’attrait vis a` vis du consommateur, ainsi que la duree a` l’obtention de ˆ de production des carcasses. Pour chaque experience, ´ de maturite´ (MW) fixes ´ d’avance et sur le cout ´ poids vifs ou de degres ˆ ˆ de 42 jours ont ete ´ sevres ´ a` l’age ´ ´ utilises; ´ les agneaux provenaient des races laitieres ` grecques 30 agneaux males, non castres, ´ ´ abattus a` un poids vif ou a` un stade de maturite´ different. ´ Boutsko (B), Serres (S) et Karagouniko (K), et ont ete Pendant la ´ ´ ´ divises ´ en trois groupes. Chacun des groupes a rec¸u une ration dont les 1ere experience, les agneaux de trois races ont ete

1

*Corresponding author. Tel.: 1 44-131-535-3233; fax: 1 44-131-535-3121; e-mail: [email protected] Present address: 17 Swanston Grove, Edinburgh, EH10 7BN, UK.

0301-6226 / 99 / $ – see front matter  1999 Published by Elsevier Science B.V. All rights reserved. PII: S0301-6226( 98 )00173-0

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´ d’aliments concentres ´ etaient ´ ´ quantites differentes (H 5 haut, M 5 moyen, L 5 bas) (192 g de M.A.T et 11.3 MJ de E.M. / kg ´ Au cours de la 2eme de M.S.) et du foin de luzerne (182 g de M.A.T et 8.3 MJ de E.M. / kg de M.S.) distribue´ a` volonte. ´ ´ ´ divises ´ en groupes qui recevaient une ration identique a` celle de la 1ere experimentation ´ experience, les agneaux ont ete (H, M ou L et foin de luzerne) pendant les 63 jours suivant leur sevrage. Puis, ils ont poursuivi leur croissance jusqu’au poids vif ´ ´ desire´ en paturant l’herbe d’une prairie artificielle (Lolium perenne et Trifolium repens). Les resultats des deux experiences montrent que la race et la quantite´ d’aliment concentre´ consomme´ ont eu une forte influence (P , 0.001) sur le G.Q.M et sur ´ ´ ´ a` l’abattage. La teneur de la carcasse en matieres ` ´ ´ tres ´ le temps necessaire pour arriver au poids vif desire grasses a ete ´ par la race et le poids vif a` l’abattage (P , 0.01) ainsi que par le niveau de consommation d’aliment concentre´ influencee ´ ´ de meilleures performances. (P , 0.001). Les agneaux finis a` la prairie ont realise Zusammenfassung In der vorliegenden Untersuchung wurde analysiert, wie unterschiedliche Ernaehrung von Laemmen dreien Griechischer Schafsrassen bis zu einer gewissen Lebendmasse, oder bis einer gewissen Proportion des Erwachsengewichts, die Zusammensetzung des Schlachtkoerpers und die potentielle Akzeptanz der Verbraucher beeinfluessen kann. Zwei Versuche wurden innerhalb von zwei Jahren ausgefuert, ein jeder mit 30 entwoehnten Laemmen (42 Tage alt) der Milchschafrassen Boutsko, Serres und Karagouniko. Die Laemmen wurden unter unterschiedlichen Ernaehrungbedingungen gehalten und wurden auf unterschiedliche Proportionen des Erwachsengewichtes geschlachtet. Die Versuche wurden gemacht, um den Effekt der Laemmenrasse und der Ernaehrungsstufe auf das Wachstum zu schaetzen sowie auf die benoetigte Zeit, um das Zielgewicht zu erreichen, und Dose die chemische Zusammensetzung des Schlachtkoerpers und auf die Kosten der Aufzuecht zu analysieren. Die Versuchstiere wurden waehrend des ersten Versuches einzel gefuettert im drei unterschiedliche Kraftfutterstufen, kombiniert mit Luzerneheu ad libitum. Das Kraftfutter enthielt pro kg Trockenmasse 192 g oheiweiss und 11,3 MJ UE und die Luzerne 182 g Roheiweiss und 8,3 MJ UE. Waehrend des zweiten Versuches wurden die Versuchstiere erst 63 Tage ehalten wie waehrend des ersten Versuches aber dann gemaestet auf einer ewaesserten Wiese mit Gras (Lolium perenne) and Klee (Trifolium repens) ie Versuche zeigten, das Laemmerrasse und Kraftfutterstufe einen etrachtlichen Effekt (P , 0.001) auf das taegliche Wachstum hatten owie auf die Zeit die benoetigt wird um das Zielgewicht zu erreichen. Rasse, Schlachtgewicht und Kraftfutterstufe hatten einen ignifikanten Einfluss (P , 0.001) auf das Sclachtkoerperfettgewicht.  1999 Published by Elsevier Science B.V. All rights reserved. Keywords: Nutritional management; Lambs; Dairy breeds; Heavier carcasses

1. Introduction The Greek sheep industry is based on milk production from relatively small farms and flocks (Zygoyiannis et al., 1995a). Production of lamb carcass meat is a secondary objective to milk production and the time of lambing and weaning is based on obtaining a long milking period after weaning until the end of lactation in the summer when feed availability declines. The peak lambing period occurs in November / December and the lambs are usually weaned and slaughtered at around 6 weeks of age. The carcass weight is low (6–10 kg) and the marketing period is relatively short; consumer demand for lamb meat after Easter tends to be met by imports (Zygoyiannis et al., 1995b). The ability to manipulate growth rate and carcass com-

position to consumer acceptable standards by nutritional management would permit more flexible rearing and marketing systems for the production of heavier lamb carcasses over an extended finishing period. The results described in this report formed part of a wider series of studies, supported by the European Commission, designed to assess the growth, development and potential carcass production in three sheep breeds each from three different LFAs (less favoured areas) in the EU. In the initial joint stage as reported by Friggens et al. (1994), lambs from all nine European breeds were reared under identical, nonlimiting nutritional conditions from weaning and were slaughtered at nominated proportions of their estimated mature weights (MW). From the initial analysis (Friggens et al., 1994) it was concluded that

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the growth potential of all nine breeds could be predicted approximately by the use of a common size-scaling rule based on the estimated MW of each breed (McClelland et al., 1976) although there were small but consistent differences amongst the breeds. This was confirmed by Zygoyiannis et al. (1997b) for the three Greek dairy breeds (Boutsko, Serres and Karagouniko) involved in the first study. In this first phase, Greek lambs targeted for slaughter at 45% of estimated MW of the breed reached these weights in 60–70 days post-weaning. The objectives of the studies, reported in this paper for the same three Greek breeds, was to assess the extent to which post-weaning growth rate within breed and, hence, the time taken to reach any defined slaughter weight, could be modified by variation in nutritional management when feeding was based on locally available, less intensive resources, including Lucerne hay, which is readily available in Greece and the grazing of sown pastures, a new approach for Greece. A second objective was to determine whether the potential carcass composition at any defined liveweight or proportion of breed MW, acceptable to the consumers, could be influenced by such nutritional treatments.

2. Materials and methods The study was carried out over 2 years on male lambs of the Boutsko (B), Serres (S) and Karagouniko (K) breeds born during the peak lambing period in late November and weaned at about 6 weeks of age in mid-December. The lambs were purchased from one flock of each breed. The flocks were semi-extensively managed breeding flocks, with both ewes and lambs kept indoors during the period of birth to weaning. The B lambs were derived from the National Agricultural Research Foundation (NARF) station in Ioannina (north-west Greece), the S lambs were from the NARF station in Serres (northern Greece) and the K lambs from the NARF station in Karditsa (central Greece). The objective in the first year was to assess the effect of finishing lambs, post weaning, by individual, indoor feeding on diets consisting of three different allowances of concentrate feed (CA) together with unchopped Lucerne hay (LH) offered ad libitum. In the

281

second year, lambs were restricted to a shorter, fixed period of group feeding on concentrate and Lucerne hay followed by a final grazing period on irrigated sown pasture. The intention was to extend the finishing period to give a more flexible marketing time at higher carcass weights (CW) that could be acceptable to Greek consumers.

2.1. Year 1: finishing of housed lambs on concentrate and Lucerne hay Thirty male lambs of each breed together with six spares were transferred to the NARF station about 25 km from Thessaloniki. They were housed in individual pens, provided with individual feed boxes and a constant supply of fresh water. The concentrate pellets (3 mm) contained 192 g crude protein (CP) / kg DM and 11.3 MJ ME / kg DM and the unchopped Lucerne hay contained 182 g CP/ kg DM and 8.3 MJ ME / kg DM, respectively (Zygoyiannis et al., 1997b). The CA, designated as H (high), M (medium) and L (low), were based on the ad libitum intakes for each breed recorded during the same period in the first phase (Zygoyiannis et al., 1997b): allowance H was set as 80% of the measured ad libitum intake at the same age whilst M and L were 66% and 33%, respectively, of the H allowance. All allowances were increased weekly by fixed proportional increments of 50 g. Any refusals of concentrate were recorded daily and hay refusals were weighed weekly. The three target slaughter live weights (TSLW), 23, 28 and 33 kg, were common to all three breeds and were based on creating a range of carcass weights (CW) from around 11 to 16 kg. This range had been found, in the previous phase of unrestricted feeding, to produce carcasses, over all breeds, which had an optimum total fat composition in relation to predicted market demands (around 16 to 22% of total CW). The TSLW represented different proportions of the respective male MW for each breed (0.41, 0.50, 0.59 (B), 0.33, 0.41, 0.48 (S) and 0.29, 0.35, 0.41 (K)) as estimated from adult ewe weights adjusted to a common body condition score of 3 and multiplied by 1.3 to provide an estimate for adult males at the same body condition score (Zygoyiannis et al., 1997a). The estimated MW were 56, 69 and 80 kg, respectively, for male lambs of B, S and K breeds. The proportion of 0.41 MW was

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common to all three breeds. Lambs were weighed weekly and were slaughtered on reaching their designated weights. Carcasses were dressed by the standard procedure and weighed after cooling (Meat and Livestock Commission, 1993). Chemical analyses for crude protein, ether extracted fat and ash were carried out on half carcasses from two lambs in each cell (Association of Official Analytical Chemists, 1990).

2.2. Year 2: finishing lambs on irrigated sown pasture For purpose of comparison, weaned male lambs of the same three breeds were obtained from the same farm sources, at the same time of year (mid to late December) and at the same mean age (6 weeks) as in year 1. The experimental lambs (30 per breed), together with six spares were transferred at weaning to a farm site in Thessalia, Central Greece. They were housed in a sheep shed with group feeding facilities until the pasture growth on the intended grazing area was deemed sufficient to allow the lambs to be turned out to graze. During the indoor period all lambs, including spares, were group fed by breed at one of three levels of CA together with an ad libitum offering of Lucerne hay. The CAs were based on, but were considerably lower than, the corresponding allowances for each breed in year 1, with a starting H level of 100 g / day in breed B, 168 g / day in S and 300 g / day in K. The M level was 60% of the H and the L was a standard 50 g / day for all breeds. The indoor feeding period lasted for 9 weeks until the pasture was ready to support grazing (15 February). The 10 lambs in each breed and post-weaning feed group were then randomly divided into two groups of five lambs and allocated to a TSLW of either 48% or 54% of breed and male MW. TSLW were 27 and 30 kg, respectively, for B, 33 and 37 kg for S and 38 and 43 kg for K. These proportions of MW were chosen in relation to the results in year 1 and to straddle the proportion of MW as recommended by MLC (Meat and Livestock Commission, 1989) to provide a guideline for target slaughter weights in order to achieve an optimum carcass composition for the market. The provision of sown pasture for grazing by finishing lambs is rare in Greece and it was neces-

sary to create an experimental plot. In view of the climatic conditions during summer (mean maximum and minimum day temperature around 348C and 178C, respectively, and mean precipitation 0.6 mm) it was recognised that irrigation would be necessary. A site was selected in central Greece (Thessalia) in a region currently devoted to the intensive cultivation of cotton. An area of 2.2 ha was ring-fenced and sown, in September of the preceding year, with a mixture containing a tetraploid ryegrass (Lolium perenne) and the New Zealand variety of white clover Huia (Trifolium repens) at a rate of 30 and 3 kg / ha, respectively. Irrigation water was applied as required in response to weekly measurement of soil water content (below 12%). After turn-out the lambs were grazed from 06:00 h to 22:00 h and were housed at night without supplementary feeding. Throughout the grazing period the sward surface height was measured weekly and was maintained at 662 cm by adjustment of the grazing area by movable fence-line or by adding or removing spare, non-experimental lambs as required. The pasture contained 167 g CP/ kg DM and 7.5 MJ ME / kg DM (mean values for the experimental period until the end of June). Lambs were weighed weekly and were slaughtered when their LW reached the TSLW. The carcasses were visually scored for fat class according to MLC guidelines and one half carcass from two lambs in each cell were retained for chemical analysis as in the previous year.

2.3. Statistical analysis The results in both years (1 and 2) were analyzed using the general linear model (GLM) procedure of the Minitab software (Minitab Inc., State College, USA) with the model used accounting for the effects of breed, CA and TSLW and their interactions. The significance of all main effects and interactions was tested against the error mean square.

3. Results

3.1. Year 1 The mean daily intakes of concentrate and hay, according to CA, TSLW and breed are shown in

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Table 1 Mean daily intake (g) from weaning to slaughter of concentrate (CA) and Lucerne hay (H) according to breed (B, S and K), target slaughter live weight (TSLW) and concentrate allowances (CA), year 1 TSLW (kg)

CA

Intake C B

23

28

33

H M L H M L H M L

Intake H S

405 255 158 470 316 171 507 359 206

K

545 386 219 626 444 241 691 503 282

B

S

K

297 423 514 282 471 615 311 451 616

342 420 640 372 488 724 350 521 711

MS

F(H)

P

41 222 57 382 814 187 3963 10 007 3645 3779 5469

7.5 10.5 148.8 0.72 1.83 0.67 0.69

552 378 190 611 424 226 674 502 266

Source of variation

df

MS

F(C)

Breed (B) TSLW Concentrate allowances (CA) B 3 TSLW B 3 CA TSLW 3 CA B 3 TSLW 3 CA Error

2 2 2 4 4 4 8 81

160 457 89 005 1 081 211 820 10 366 3316 233 499

321.8 178.5 2168.7 1.65 20.8 6.65 0.47

P 0.000 0.000 0.000 0.171 0.000 0.000 0.876

271 439 581 350 484 619 371 596 665

0.001 0.000 0.000 0.578 0.131 0.617 0.698

***P , 0.001; NS, . 0.05.

Table 1. In general, the largest breed (K) consumed the highest daily amount of hay, whereas the intermediate breed (S) consumed the lowest amount and, in all breeds hay consumption increased as CA was reduced from H to L, and as slaughter liveweight increased. Mean daily liveweight gains according to breed, TSLW and CA and the time, in days, taken to reach TSLW are shown in Table 2. Since mean weaning weights were different, the total LW gain was greater in the B lambs than in the S which in turn required more than K lambs to reach the same target LW (10.5, 8.3 and 6.1 kg, respectively). Growth rate was significantly affected by breed (P , 0.001), TSLW (P , 0.001) and CA (P , 0.001). There was a significant interaction (P , 0.01) between breed and CA, mainly due to the lack of difference in DLWG in B lambs offered either the H or M levels of CA. The time to reach each target TSLW was significantly affected by breed (P , 0.001), including effects of differences in both CA (P , 0.001) and TSLW (P , 0.001). There was again a significant interaction (P , 0.001) between breed and CA.

The total feed costs for each lamb from start to slaughter on reaching its TSLW, were calculated from the above results using the average cost of concentrate or hay at the time of the study (100 DRA / kg for concentrate and 60 DRA / kg for hay). The differences amongst breeds were relatively small with overall costs of 438, 422 and 393 DRA / kg LWG for B, S and K lambs, respectively. Similarly, the cost difference according to CA was also small ranging from 444 DRA / kg LWG at the L level to 403 DRA / kg LWG at the H level. Carcass acceptability, in terms of proportion of fatty tissue (g / 100 g of carcass) as assessed from ether extract (EE) chemical analysis converted by the equation relating EE and fat derived in the first year: F (g / kg) 5 2 232 1 0.873EE (Zygoyiannis et al., 1994) is shown in Table 3. In general, the results indicated that fat content of the carcass increased with carcass weight in all breeds (P , 0.001), was highest at all carcass weights in B breed, lowest in the S breed (P , 0.01) and intermediate in K. The increase was also significantly affected by CA (P , 0.01).

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Table 2 Mean daily liveweight gain (DLWG, g) and mean number of days (D) between weaning and slaughter, according to breed, target slaughter live weight (TSLW) and concentrate allowances (CA) (year 1) TSLW

CA

DLWG

D

B 23

H M L H M L H M L

28

33

136 150 99 148 145 127 167 163 131

Source of variation

df

MS

Breed (B) TSLW Concentrate allowances (CA) B 3 TSLW B 3 CA TSLW 3 CA B 3 TSLW 3 CA Error

2 2 2 4 4 4 8 81

20 627.1 5979.6 26 516.5 294.8 1981.7 172.0 279.2 372.1

S

K

198 155 112 202 175 146 219 176 139

196 164 150 228 202 166 229 189 168

F

P

55.43 16.07 71.25 0.79 5.33 0.46 0.75

B

0.000 0.000 0.000 0.534 0.001 0.763 0.647

S

K

41 51 75 64 76 94 83 102 130

35 37 38 49 55 66 71 86 97

MS

F(D)

P

25 262.5 21 991.8 6808.2 47.5 499.9 253.0 85.2 69.8

361.79 314.15 97.50 0.68 7.16 3.62 1.22

79 70 108 106 110 124 121 130 158

0.000 0.000 0.000 0.608 0.000 0.009 0.298

***P , 0.001; **P , 0.01; NS, . 0.05.

Table 3 Proportions of fat (g / 100 g) in the carcass according to breed, target slaughter live weight and concentrate allowances (year 1) TSLW

CA

23

H M L H M L H M L

28

33

B 18.2 21.3 20.7 24.7 22.8 23.0 28.3 22.3 22.3

S

K

18.2 15.0 17.5 17.7 13.3 16.0 23.9 17.6 21.0

17.2 20.3 17.1 20.8 16.3 17.1 26.5 18.5 18.7 P

Source of variation

df

MS

F

Breed (B) TSLW Concentrate allowances (CA) B 3 TSLW B 3 CA TSLW 3 CA B 3 TSLW 3 CA Error

2 2 2 4 4 4 8 27

112.2 79.6 34.4 5.9 3.3 14.2 6.1 5.7

19.72 13.99 6.05 1.04 0.58 2.49 1.08

***P , 0.001; **P , 0.01; NS, . 0.05.

0.000 0.000 0.007 0.407 0.677 0.067 0.408

3.2. Year 2 As in the previous year, reduced levels of CA were partially compensated by increase in the consumption of Lucerne hay (Table 4). Although the effect of breed was not significant, there was an indication of an upper limit of hay consumption in all breeds corresponding to the M level of CA. The mean DLWG during the 9-week indoor group feeding is shown according to breed and CA in Table 5. As in year 1, there was an interaction between breed and CA (P , 0.001) so that, whilst DLWG was affected by CA in both K and S breeds, there were no significant differences within the B breed. After turn-out to pasture the average stock density until early June, when most of the experimental lambs had reached TSLW, was 35 lambs per ha. The mean DLWG and time in days from turn-out to slaughter is shown in Table 6. DLWG was significantly affected by breed (P , 0.001) and to a

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285

Table 4 Mean daily consumption of concentrate (C) and hay (LH) (g) by breed, and concentrate allowances (CA) from weaning to turnout to grazing (year 2) CA

Intake of concentrate (C) B

H M L

156 115 78

Intake of hay (LH)

S

K

414 244 78

444 256 78 P

Source of variation

df

MS

F(C)

Breed (B) Concentrate allowances (CA) B 3 CA Error

2 2 4 72

168 021 456 371 56 554 2980

56.39 153.16 18.98

B 542 585 595 MS 0.000 0.000 0.000

161 268 46 904 18 161 120 460

S

K

629 641 634

622 770 791

F(H)

P

1.34 0.39 0.15

0.269 0.679 0.962

***P , 0.001; NS, . 0.05. Table 5 Mean daily liveweight gain (DLWG, g) from weaning to turnout to grass by breed, proportion of mature weight (PMW) at slaughter and concentrate allowances (CA) (year 2) PMW

CA

0.48 MW

H M L H M L

Breed B

0.54 MW

116 127 126 130 134 123

Source of variation

df

MS

Breed (B) TSLW Concentrate allowances (CA) B 3 TSLW B 3 CA TSLW 3 CA B 3 TSLW 3 CA Error

2 1 2 2 4 2 4 72

24 135.1 65.9 23 121.9 134.9 8219.2 15.4 180.1 760.5

S

K

218 167 114 219 160 113

203 199 139 196 207 143

F

P

31.73 0.09 30.40 0.18 10.81 0.02 0.24

0.000 0.769 0.000 0.838 0.000 0.980 0.917

***P , 0.001; NS, . 0.05.

lesser extent by proportion of MW (P , 0.01) and CA (P , 0.05) during the indoor period. There was a significant (P , 0.01) interaction between breed and CA in DLWG. Time to reach a given TSLW was significantly affected by breed, proportion of MW (P , 0.001) and CA (P , 0.01). The carcass fat content, as assessed by chemical analysis, is shown in Table 7. As in the previous year, there was considerable variation within the small number of samples per cell. There appeared to

be little difference between the breeds when compared at the same proportion of MW, although the S breed did have consistently lower values. There were no consistent effects of CA during the pre-grazing period and only small differences between groups slaughtered at 0.48 or 0.54 MW. On the whole, these results may indicate a lower fat content of carcasses finished on grass under the present system than when the same breeds were finished in individual pens indoors on a diet of concentrate and hay.

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Table 6 Mean daily liveweight gain (DLWG, g) and length of time (days) from turnout to slaughter affected by breed, proportion of mature weight (PMW) at slaughter and level of concentrate during the indoor period of lambs finished at pasture (year 2) PMW

CA

DLWG

Time

B 0.48 MW

H M L H M L

0.54 MW

126 131 124 155 130 153

S

K

161 221 232 182 215 224

183 191 221 250 226 201 P

Source of variation

df

MS

F

Breed (B) TSLW Concentrate allowances (CA) B 3 TSLW B 3 CA TSLW 3 CA B 3 TSLW 3 CA Error

2 1 2 2 4 2 4 72

76 870 5018 3458 914 3266 1044 458 699

109.97 7.18 4.95 1.31 4.67 1.49 0.66

B

0.000 0.009 0.010 0.277 0.002 0.231 0.625

S 49 49 49 57 69 59

K

41 46 56 56 66 74

60 55 66 66 67 92

MS

F(T)

P

55 910.2 5137.8 974.4 48.3 410.4 160.1 116.9 184.3

303.36 27.88 5.29 0.26 2.23 0.87 0.63

0.000 0.000 0.007 0.770 0.074 0.424 0.640

***P , 0.001; **P , 0.01; *P , 0.05; NS, . 0.05.

Table 7 Proportion of fat in carcass (g / 100 g) affected by breed, proportion of mature weight (PMW) at slaughter and level of concentrate (CA) during the indoor period of lambs finished at pasture (year 2) PMW

0.48 MW

0.54 MW

CA

H M L H M L

Breed B

S

K

16.1 16.4 15.0 13.9 18.4 17.5

14.1 16.5 11.6 12.8 16.6 17.5

13.8 16.6 16.2 19.0 19.3 18.0

F

P

Source of variation

DF

MS

Breed (B) TSLW Concentrate allowances (CA) B 3 TSLW B 3 CA TSLW 3 CA B 3 TSLW 3 CA Error

2 1 2 2 4 2 4 18

16.069 31.006 16.680 4.758 0.691 6.167 9.085 6.105

*P , 0.05; NS, . 0.05.

2.63 5.08 2.73 0.78 0.11 1.01 1.49

0.099 0.037 0.092 0.474 0.976 0.384 0.247

4. Discussion The three breeds, involved in this study, are classified as dairy breeds. It has been suggested (Wood et al., 1980; Butler-Hogg and Whelehan, 1986) that dairy breeds may deviate from the general scaling rules as described by McClelland et al. (1976). This suggestion was based on results from the East Friesland breed as the only example of dairy sheep. Doney et al. (1987) confirmed this difference between the East Friesland and representative British breeds but Zygoyiannis et al. (1990) in a comparison of the growth and development of the East Friesland with two indigenous Greek dairy breeds, including the Karagouniko represented here, found that the East Friesland differed significantly from the other two. In the first phase of the present project covering nine dairy and non-dairy breeds from different European regions, where all lambs were reared in a nutritionally non-limiting environment (Friggens et al., 1994) only minor differences were found and these may have been related to the estimates of MWs

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used in the study. It can be suggested, then, that the Greek dairy breeds do not differ from the general scaling rules and that these rules can be used as guidelines relating growth and carcass composition of the breeds when taken to equivalent proportions of the MW appropriate to their breed and sex. The present study, therefore, investigated the extent to which growth rate, carcass composition and the time scale from weaning to a potential commercial slaughter weight, greater than that which is traditional in the Greek breeds, could be modified by a range of nutritional systems making greater use of readily available local feed resources. In both years the liveweight at weaning, at | 6 weeks of age, in the B, S and K lambs represented equivalent proportions of the estimated MW for breed and sex. During the feeding periods with different levels of restricted concentrate and ad libitum Lucerne hay — up to target slaughter weight in year 1 and to turn-out to grass in year 2 — the voluntary intake of hay increased in response to reduction in the concentrate allowance and was highest in the largest breed (K) and least in the smallest breed (B). Mean daily liveweight gain was significantly increased by CA in the two larger breeds, S and K, but not, except for the lowest CA, in the slower maturing breed, B. This would indicate that different feeding strategies may be adopted according to the mature weight of the breed. In year 1, as a consequence of differences in weaning weight and DLWG and the common TSLWs across the breeds, the length of time taken to reach a given slaughter weight was highest in B and lowest in K, confirming that the Boutsko is a slow maturing breed. However, as expected, when compared at an equal proportion of MW (42%), the time difference amongst breeds was largely eroded and was mainly affected by CA. Feeding strategies, designed to extend the marketing period of a heavier carcass with a consumer acceptable composition, must, therefore, take account of the MW of the breed (or crossbreed, since most commercial flocks do not carry pure-bred animals) and the targeted marketing date. The key factor is the time between lambing and the targeted marketing date which is affected by seasonal fluctuations in market prices. In year 2, when early born lambs were group fed prior to turn-out to grass, the DLWG on comparable

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CA were, in general, similar to those in the first year although slightly higher. The difference could possibly be an effect of group feeding as compared to single pen feeding of animals with a high level of flocking behaviour. At pasture the DLWG of all lambs compared favourably with those achieved by each breed on the higher levels of CA during the indoor feeding period and the time taken to reach corresponding proportions of MW was, in general, similar although the K breed appeared to take slightly longer. This suggests that grazing of sown pasture, as provided, can represent a satisfactory finishing system for early born lambs to give a marketing date for heavier carcasses ranging from early April to early June. It can be assumed that this resource, giving an alternative to intensive cropping systems in suitable regions, can also be used effectively to extend the marketing period of later born lambs for which it may be even more appropriate (the experimental plot continued to be utilised by non-experimental lambs up to October). Given the small sample sizes of the chemical analyses of the carcasses, it is difficult to draw firm conclusions on the carcass composition to be expected from any of these extended rearing systems. The results do suggest, however, that the slower rearing systems may result in lower proportions of carcass fat at equivalent weights as compared with a nutritionally unrestricted regime (Pal et al., 1997; Demise et al., 1998). The results also suggest that when slaughtered at around 42% of MW, or possibly higher, all breeds could produce market acceptable carcasses when reared from weaning on the types of diet described (mean fat levels of 19.8, 15.6 and 21.2 g / 100 g for B, S and K, respectively). A further study on the fatty acids composition of carcass fat showed that the polyunsaturated / saturated (P/ S) ratio was higher in carcasses from lambs reared on irrigated pasture (Arsenos, 1997). In year 1, the results indicated that, when slaughtered at 42% of MW, the mean fat content was lowest in S (164 g / kg), intermediate in B (198 g / kg) and highest in K (213 g / kg) corresponding to an MLC score of 3L to 3H. After finishing on even lower levels of concentrate followed by grass in year 2, the estimates of fat content at 48 and 54% MW were, on the whole, lower (146, 162 and 171 g / kg, respectively; scores 2 to 3L).

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Development of these system options depends on the willingness of the Greek consumers to accept larger carcasses, possibly with different presentation, and the ability of the meat marketing industry to adapt. Studies on these aspects were carried out at the same time as the nutritional studies (Scanlan et al., 1994; Zygoyiannis et al., 1995b). It was concluded that the Greek market for lamb was dominated by the consumption of milk-fed lambs mainly during Christmas and Easter. The mean preferred size of lambs carcass was slightly under 10.5 kg. The main objection to heavier lambs was that they were regarded as being over fat. Around 50% of the consumers thought the size of the carcass was a very important factor and more than 80% thought the carcass fat level was a very important factor which influenced their decision to purchase lamb. Despite this, the trials also showed that the Greek consumers were prepared to accept heavier carcasses with a limited amount of fat, especially when presented with specific joints or meat cuts (Yannakopoulos et al., 1994).

5. Conclusions The results of this study indicate that manipulation of post-weaning nutritional systems, based on locally available feeds, including the provision of sown pasture, can be used to produce consumer acceptable carcasses at much heavier weights than those which are traditional in Greece. Furthermore, the marketing period can be significantly extended to avoid the current oversupply at traditional marketing times. Specific systems will obviously vary according to the cost of the local resources, the MW of the breed or cross involved and the market requirements relating to carcass composition. However, this study clearly demonstrates that there is potential for development in such systems. In all such systems, the final decision on market readiness must be based on the assessment of the individual animals in the flock.

Acknowledgements The work was supported by the European Commission (DG VI) project no. CAMAR 8001-CT 91

0308, as part of a collaborative programme between the United Kingdom, Greece and Spain. The farmer Mr G. Zygoyiannis, his wife Panagiota and their son Themistocles are greatly acknowledged for their assistance in animal and pasture management.

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