The Reproductive Performance of British Breeds of Sheep in an Equatorial Environment. II. Lowland Breeds

The Reproductive Performance of British Breeds of Sheep in an Equatorial Environment. II. Lowland Breeds

Br. vet.]. (1971), 127, 10 THE REPRODUCTIVE PERFORMANCE OF BRITISH BREEDS OF SHEEP IN AN EQUATORIAL ENVIRONMENT. II. LOWLAND BREEDS BY T. BEATY* AN...

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Br. vet.]. (1971), 127, 10

THE REPRODUCTIVE PERFORMANCE OF BRITISH BREEDS OF SHEEP IN AN EQUATORIAL ENVIRONMENT. II. LOWLAND BREEDS BY

T.

BEATY* AND

H.

LL. '"'ILLIAMS

Ministry of Overseas Development, Apartado Aereo 828, Pasto, Colombia, and Department of Animal Husbandry & Veterinary Hygiene, The Royal Veterinary College, Boltons Park, Potters Bar, Hertfordshiret

SUMMARY

The paper describes the reproductive performance of 44 Romney Marsh, r6 Dorset Down, 23 Hampshire Down ·and r6 Border Leicester ewes during two "seasons" following their arrival at Pasto, Colombia. In season I the percentage keel marked were 93·2, 87·5, roo·o and o·o, respectively, and the percentage lambed were 68·2, 50·0, 52·3 and o·o. In season II the percentages were 97·7, roo·o, roo·o and 56·3 keel marked and 79·5, roo·o, roo·o and 37·5 lambed. INTRODUCTION

A general description of the sheep unit and the local climate at Pasto, Colombia was given in Part It, together with the performance of the "Mountain" breeds (Beaty and Williams, 197I). This part includes the performance of the groups of Romney Marsh, Dorset Down, Hampshire Down and Border Leicester ewes. LOCATION, MANAGEMENT AND LIVESTOCK

The "lowland" groups were kept at Finca Lofe, Pasto at an altitude of 2700 metres. At first, most of the pastures were dominated by kikuyo grass (Pennisetum clandestinum). A programme of grassland improvement was undertaken which resulted in an increasing acreage of perennial rye-grass and white clover swards. The ewes were maintained on pasture throughout the year. Although the ewes were given access to proprietary mineral blocks containing o·o3 per cent potassium iodide, symptoms of iodine deficiency appeared in the lambs of all breeds born March-April Ig68. In addition to the mineral blocks, the ewes were given a weekly drench containing 50 mg. KI from May Ig68 onwards. Two Romney Marsh, three Dorset Down, three Hampshire Down and two Border Leicester rams were used during the two seasons. The rams were fitted with keeling harnesses during all service periods; the colour crayons were changed every I 7 days. *Present address: c/o British Embassy, Bogota, Colombia. t Reprints available from this address. + This issue, p. 1.

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The 44 Romney Marsh sheading ewes arriving at Pasto in October 1966 were then served. Forty-one of the ewes lambed in March 1967. Fifteen ewe lambs were selected and retained for breeding purposes. The majority of the I6 Dorset Down yearling ewes were pregnant at the time of importation. Twelve ewes lambed during April 1967; two ewe lambs were kept for breeding. The 23 Hampshire Down ewes were also yearlings at the time of arrival; I 2 ewes lambed during March and April I 967. The I 6 Border Leicester females were 9-Io months of age at the time of importation. The last three breeds arrived at Pas to in January I 967. This assessment of reproductive performance covers two breeding "seasons." The first started on 18 September 1967, when the rams were re-introduced to their respective breed groups. The second season was from March/April 1968 to April I969. PERFORMANCE

Romney Marsh Season I. The level of mating activity subsequent to the re-entry of the ram on I8 September I967 is illustrated in Fig. I. The only occasion when the level of recorded services exceeded 50 per cent was during service period 5, commencing on 26 November. However, it must be noted that half the group had been effectively served during the earlier periods. No ewes were keel marked between I7 January and 27 April I968. The breeding performance is summarized in Table I. The mean lambing date of the 30 ewes was 24 March 1968. Twenty-two lambings occurred during February and March and the remaining eight ewes lambed in April (5) and May (3). Season II. The fifteen ewe lambs born in March I 967 joined the parent group on I5 May I968. Unlike season I the rams had remained with the parent group and therefore there was no intentional restriction of mating periods. The incidence ofmatings in the eligible imported group from 28 April onwards is illustrated in Fig. 2. "Eligible" ewes included ewes which were barren during the previous season, TABLE I BREEDING PERFORMANCE OF ROMNEY MARSH EWES. SEASON I.

Number No. in group I8.g.67 Ewes keel marked No. lambing to services in service periods I-4 subsequent periods Total ewes lambing No. lambing to first service subsequent service(s) Barren ewes Barren ewes with I recorded service(s) 2 recorded service (s) 3 recorded service(s) No recorded services

Percentage

44

4I 24 6

30 20 IO

I4 8 2

3

93"2

BRITISH VETERI NARY JOURNAL,

I2

I 27, ~

0

z

2

3

4

5

7

6

8

Sept

Nov

Jan

19 1967

26

17

9

10

II

12

13

April 27 1968

Serv1ce periods ( 17 days)

D

Fig.

I.

~No.

Na eligible

kee l marked

The incidence of keel marking during each service period in the Romney Marsh group during season I.

non-pregnant ewes and ewes which had lambed at least two months prior to the first day of the service period. Fig. 2 also gives the incidence of matings in those born at Pas to in March I g67. It can be seen that keel m arks were recorded up to service period ending 5 December I g68 . Periods 4 and 5 had the highest incidence of keel marking in the parent group . Period 5 (5 J uly-22 July) was also the period of peak activity for those born at Pasto. There was no evidence of activity between 6 D ecember Ig68 and 20 April Ig6g . Only one of the 44 imported ewes was not keel marked. Eight of the I 5 ewes born at Pas to were not marked. Beaty & TABLE II I NCIDENCE OF EFFECTIVE SERVICES PER SERVICE PERIOD ACCORD IN G TO STA T US I N ROMNEY MAR SH EWES. SEASON II . I 7-day service period ending:

May I 4 May 3I June I7 July 4 July 22 August 8 August 25 August 26-November I8

Lambed Feb-March

Lambed April-May

Barren previous season

Born Pasta I967

(22)

(8)

( I4)

( IS )

I 0 0

4 I4

0 0

0

0

0 0

2

2

0 0 0

0 0

0 0

0 0 0

3

3 22

3

10

6

BRITISH LOWLAND SHEEP IN COLOMBIA 45

37

2

3

Born pasto ma rch

4

July 4

Apr il 28 1968

Oec 5 1968

Aug 25 Service periods

15

'5

15

15

12

12

12

12

10

10

10

9

Nos. eligible

0

0

0

5

0

0

0

2

0

0

2

0

Nos. keel marked

1967 D No. eli91 ble

Fig.

2.

~No. kee l

morked

The incidence of keel marking in the imported Romney Marsh group and those born at Pasto March 1967, during season II.

Williams (1970) have compared the performance ofthese parent and offspring groups of Romney Marsh ewes with similar groups of Welsh Mountain ewes. Thirty-five (79·5 per cent) ewes of the imported group lambed, 31 (70·5 per cent) conceived to first service. Only six of those born at Pasto lambed. The incidence of effective services during each service period, and according to the status of the ewes, is given in Table II. The most satisfactory performance was that of the "lambed February-March" sub-group. All these ewes lambed: their mean lambing interval was 273 days. Eighteen of these 22 ewes conceived between 4 July and 22 July.

Dorset Down Season I. Only two ewes were not keel marked, the remaining 14 ewes were all marked during the first four service periods. Seven ewes (so·o per cent) lambed to first service. The incidence of keel markings and effective services in each service period is given in Table III, which also includes a summary of the breeding performance. No keel marks were observed between 27 November 1967 and 26 March 1968. Eight ewes (5o·o per cent) lambed during February and March 1968. Season II. The rams were not withdrawn during Season I. Season II commenced on 27 March when mating activity re-appeared in the group. The incidence of matings is presented in Table IV according to the status of the ewes. The sub-group of eight ewes which were barren in the previous breeding season showed a high level of activity during the first three service periods. Seven ewes were marked by I May and the remaining ewes on 19 June. In

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the other sub-group two ewes were first marked in April, three in May and three in June. Seven ewes in the "barren" sub-group conceived to first or second service compared with four in the "lambed" sub-group. All ewes produced lambs. The mean lambing interval of the eight ewes which lambed in both season was 267 days (range 209-3I8 days). The two ewes born at Pas to in April I 967 were marked on 8 August and I 9 June; both produced lambs. TABLE III BREEDING PERFORMANCE OF THE DORSET DOWN EWES. SEASON I.

Service periods ending: 4.I0.67 22.I0.67 8.I r.67 26.I r.67 27.I r.67-26.3.68

No. keel marked 6 9 3

No. effective services 2

I

6 0 0

0

0

No. in group I8.g.67 Ewes keel marked No. lambing to services in service periods I-4 subsequent periods Total ewes lambing No. lambing to first service subsequent service(s) Barren ewes Barren ewes with I recorded service(s) 2 recorded service(s) 3 recorded service(s) No recorded services

Mean lambing date and range

Number I6 I4 8

Percentage

0

8 7 I

8 3 2 I

2

Feb 26 (Feb

I

r-March 17)

Hampshire Down Season I. A percentage of 52 ·4 of the group were keel marked during the firstservice period. Markings were confined to the first four service periods during which all ewes were served. Eleven ewes (52·3 per cent) lambed, nine of them to first service. The mean lambing date was 27 February (I I February-26 March). The rams remained with the ewes, no keel marks were observed during the period 27 November to 20 February (Table V). Season II. One isolated service and conception occurred in late February I968. Table VI shows that the main period of mating activity was initiated in April. The incidence of keel marking and effective services are presented according to the status of two sub-groups during the previous season. First markings occurred mainly in April in the "barren" sub-group when eight of the ewes were marked from IO April to 29 April; the remaining three ewes were first marked from 2 May to 5 May. Three ewes in the "lambed" subgroup were first served in April, five in May, two in July and one in August. There was no difference between the two sub-groups in the proportion of the

BRITISH LOWLAND SHEEP IN COLOMBIA

IS

ewes conceiving to first and second service. The mean lambing interval of the eleven ewes which lambed in both seasons was 276 days (range 218-357 days).

TABLE IV INCIDENCE OF MATINGS PER SERVICE PERIOD ACCORDING TO STATUS IN DORSET DOWN EWES. SEASON II.

Lambed February-March

Barren previous season

(8)

No. keel marked 0 2 3 2 3 5

(8)

No. effective services 0 0 I

0 3

2

Service period ending: 12/4/68 27/4/68 14/5/68 3 rJ5J68 17/6/68 4/7/68 22/7/68 8/8/68 25/8/68

No. keel marked

No. effective services

5

4

I

0 0

I

2 I

I

0 0

0 0

No. conceiving to: First service Second service Third service Fourth service

3 3

6 I

0

8

8

TABLE V BREEDING PERFORMANCE OF HAMPSHIRE DOWN EWES. SEASON !.

Service periods ending: 4-10.67 22.10.67 8.! !.67 26.11.67 27.11.67-20.2.68

No. keel marked r6 7 6 2 0

No. effective services 7 3 0 0

No. in group r8.9.67 Ewes keel marked No. lambing to services in service periods 1-4 subsequent periods Total ewes lambing No. lambing to first service subsequent service(s) Barren ewes Barren ewes with 1 recorded service(s) 2 recorded service(s) 3 recorded service(s) No recorded services Mean lambing date and range

Number 21 21

Percentage 100'0

II

0 II

9

52'3 42'9

2

10 4 2 2 2

Feb 27 (Feb 11-March 26)

16

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TABLE VI INCIDENCE OF MATINGS PER SERVICE PERIOD ACCORDING TO STATUS IN HAMPSHIRE DOWN EWES. SEASON II.

Lambed February-March (II ) No. No. keel marked e.ffective service 0 0

0 0

0

0

3 4 2 2 5

0

I

I

I

3

0

0

3

3

I

0

0 I

0

0 0

0

0

0

I

0

Service Barren previous season Lambed February-March

Barren previous season (12) No. No. keel marked effective services

Service period ending: 9/3/68 26/3/68 12/4/68 27/4/68 14/ 5/68 3 115!68 17/6/68 4/7/68 22/7/68 8/8/68 25/8/68 11 /9/68 28/9/68 15/ I0/68 r j 11 j68 18j 11j68 5/12/68

I

0

0

7 6 4 3 5 4

I

0 0

2 3

I

I

0

0 0

0

0

No. of ewes conceiving 2 3 5 5

3

2

3

0

0 0

0

0

0

0

6

4

5

2 2

I

I

0

0

Border Leicester The I6 females were g-IO months of age at the time of their arrival in January I g67. As in the other "lowland" breeds the tupping season of I g67 /68 started on I 8 September. No heats were recorded during this season and no lambs were born. The rams remained with the ewes. From July I g68 onwards nine ewes were keel marked, of which six lambed. The details of their breeding performance are given in Table VII. TABLE VII DATES OF OESTRUS AND LAMBINGS OF NINE BORDER LEICESTER EWES

Ewe no. 41 42 43 47 48 49 51 54 55

23/7/68

Date(s) of Oestrus 9/11/68 28/8/68 r6/9/68 14/ r 1j68 6/r r/68 7/I r/68 22/9/68 6/r 1j68 4/11/68 12/r r/68 4/8/68 27/8/68 4/ 11j68

Date of lambing 23/3/69

2/4/69 21/3/69 3/4/69 22/1/69 26/3/69

Breed and Season Comparisons The incidence of lambing in all breeds during seasons I and II is shown in Table VIII. The performance of the Romney Marsh ewes during their earlier season is also shown.

BRITISH LOWLAND SHEEP IN COLOMBIA TABLE VIII IN C IDEN C E OF KEEL MARKING AND LAMBING IN ALL BREEDS ( PERCENTAGE, WITH N U MBER IN BRACKETS )

Breed Served following arrival October rg66 No. Lambing

Romney Marsh

Dorset Down

Hampshire Down

B order Leicester

44 93'2 (41 )

X

X

X

Season I Rams in r8/g/67 No. K eel marked Lambing

44 93'2 (41 ) 68·2 (go)

r6 87·5 (r4) 50'0 (8)

21 roo·o (21 ) 52·3 (rr )

r6

Season II Rams left in No. K eel marked Lambing

44 97'7 (43 ) 79'5 (35)

r6 roo·o (r6 ) roo·o (r6)

23 roo·o (23 ) roo·o (23 )

0 0

r6 56·3 (g) 37'5 (6)

Compared with season I, all breeds showed an improvement during season II. All ewes in two breeds, Dorset Down and Hampshire Down, produced lambs in season II. The six Border Leicester ewes which produced lambs in season II were the only ewes to produce lambs following their arrival early in rg67. The highest incidence of effective services in any four consecutive service periods for both seasons is shown in Table IX. In season I the four service periods immediately following the entry of the rams on r 8 September proved to have the highest incidence. TABLE IX HIGH ES T I N CIDENCE OF EFFECTIVE SERVICES IN ANY FOUR CONSE CU TIVE SERVICE PERIODS

Season I Following entry of ram on r8fg/67 Season II

Romney Marsh Percentage

Dorset Down Percentage

54'5 (24 out of 44)

50'0 (8 out of r6)

70'5 (31 out of 44) 18/6/68-25/8/68

Barren season I: 75·o (6 out of8) 27/3/68-31 /5/ 68 Lambed season I: 75'0 (6 out of8) I /6/68-8/8/68

Hampshire Down Percentage

52·4 (11 out of 21 ) 56·5 (1goutof23) r8/6/68-25/8/68

Unlike the "mountain" groups (Beaty & Williams, 1971) the rams remained with the groups in season II. There was close similarity in the behaviour of all Romney Marsh and Hampshire Down ewes, irrespective of their previous breeding history. In the Dorset Down breed, the groups which were barren during the previous season showed the most uniform activity during the

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periods 27 March to 3I May, whereas the comparable periods for those which lambed in season I were from I June to 8 August. DISCUSSION

The information provided by a system of management involving the exposure of ewes to entire rams, is limited to the attainment of first service and any subsequent services which may occur. Absence of keel marking does not allow a distinction to be made between failure to exhibit cyclic activity following ineffective service, and pre-natal mortality. The presence of "barren" ewes in all breed groups during season I together with absence of keel marking should not be interpreted as evidence of true "seasonal" anoestrum. The data on Romney Marsh and Dorset Down ewes indicates that status in season I was not a reliable guide to the pattern of accession to breeding activity in the subsequent season. In the Dorset Down group the "barren" ewes were earlier than the lambed group; whereas there was little difference between the "barren" and the "lambed" Romney Marsh ewes. Since the cause ofinfertility was not established these data give no indication of the effects of the various components of the environment. Further investigation has been initiated to establish the effect of iodine deficiency and of a simulated equatorial photoperiod on the reproductive efficiency of various breeds. It is evident that the performance of all breeds was unsatisfactory during season I. Their performance during the second season shows considerable improvement and is similar, in this respect, to the performance of the Scottish Blackface and Cheviot groups kept at Granja Obunoco during the two seasons (Beaty & Williams, I97I ) . The performance of the Border Leicester group is partially in keeping with the reports of Anderson cited by Yeates ( I965). It may be of some significance that this breed is said to be related to the North Country Cheviot (Fraser & Stamp, I957 ) . ACKNOWLEDGMENTS

One of the authors (H. Ll. W.) wishes to thank the Ministry of Overseas Development for the opportunity to visit Pasto and Mr and Mrs Tom Beaty for their generous hospitality. The Colombian organizations Instituto Colombiano Agropecuario and Servicio Nacional de Aprendizaje are thanked for the ready co-operation and assistance of their staff. REFERENCES

ANDERSON,]. (I964)· 5th Int. Congr. Anim. Reprod. A.I., Trento, I964, 3· 465. BEATY, T. & WILLIAMS, H . Ll. (I970). Br. vet.]., u6, vii. BEATY, T. & WILLIAMS, H. Ll. (I97I). Br. vet.]., 127, I. FRASER, A. & STAMP,]. T. (I957). Sheep Husbandry and Diseases. London: Crosby, Lockwood & Son. YEATES, N. T. M. (1965). Modern Aspects of Animal Production. London: Butterworth. (Accepted for publication 30 June I97o)

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La reproduction chez les races de moutons britanniques en milieu equatorial. D. Races des basses terres (Beaty et Williams) Resume. Cet article decrit la reproduction de 44 brebis des marais Romney, 16 des Downs du Dorset, 23 des Downs du Hampshire et r6 de la lisiere de Leicester, pendant deux "saisons" apres leur arrivee a Pasta, en Colombie. Pendant la saison I les pourcentages marques a l'ocre rouge etaient respectivement de 93,2, 87,5, roo,o et o,o, et les pourcentages ayant agnele etaient de 68,2, so,o, 52,3 et o,o. Pendant la saison II les pourcentages marques a l'ocre rouge etaient de 97,7, wo,o, wo,o et s6,3 et les pourcentages ayant agnele de 79,5, roo,o, roo,o et 37,5. Die Reproduktion britisch geziichteter Schafe in aquatorialer Umgebung. D. Tieflandziichtungen (Beaty und Williams) Zusammenfassung. Beschrieben wird das reproduktive Verhalten von 44 Romney Marsh, r6 Dorset Down, 23 Hampshire Down und r6 Border Leicester Mutterschafen wiihrend zweier Brunftperioden nach ihrer Aukunft in Pasto, Kolumbien. In der ersten Periode wurden mit Ri:itel bezeichnet 93,2, 87,5, 1oo,o und o Prozent und es lammten 68,2, so,o, 52,3 und o Prozent. In der zweiten Periode waren 97,7, roo,o, roo,o und 56,3 Prozent mit R i:itel markiert und es lammten 79,5, 10o,o, wo,o und 37,5 Prozent.

La actuacion reproductiva de castas britanicas de ovejas en un ambiente ecuatorial. D. Castas llaneras (Beaty y Williams) Resumen. Esta ponencia describe la actuaci6n reproductiva de 44 ovejas Romney Marsh, r6 Dorset Down, 23 Hampshire Downy r6 Border Leicester durante dos "estaciones" d esde que llegaron a Pasto, Colombia. En la primera estaci6n el porcentaje de ovejas criadas fue de 93,2, 87,5, roo,o y o,o respectivamente, y el porcentaja que produjo corderos fue de 68,2, so, o, 52,3 y o,o. En la segunda estaci6n los porcentajes fueron de 97,7, wo,o, roo,o y 56,3 criadas y 79,5, roo,o, roo,o y 37,5 que produjeron corderos.