The Reproductive Performance of British Breeds of Sheep in an Equatorial Environment. I. Mountain Breeds

The Reproductive Performance of British Breeds of Sheep in an Equatorial Environment. I. Mountain Breeds

THE BRITISH VETERINARY JOURNAL Vol. I January I 97 I 27 No. I THE REPRODUCTIVE PERFORMANCE OF BRITISH BREEDS OF SHEEP IN AN EQUATORIAL ENVIRONME...

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THE BRITISH VETERINARY JOURNAL Vol.

I

January I 97 I

27

No.

I

THE REPRODUCTIVE PERFORMANCE OF BRITISH BREEDS OF SHEEP IN AN EQUATORIAL ENVIRONMENT. I. MOUNTAIN BREEDS BY

T.

BEATY* AND

H.

LL. WILLIAMS

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

SUMMARY

The paper describes the reproductive performance of 66 Welsh Mountain, 45 Scottish Blackface and 70 North Country Cheviot ewes during two breeding "seasons" following their arrival at Pasto, Colombia early in rg67. Season I commenced on r8 October 1967 when the rams were re-introduced to their breed group. Season II commenced on 24]uly 1968. In season I, 89 ·4 per cent, 68·g per cent and 50·0 per cent of the Welsh Mountain, Scottish Blackface and Cheviot ewes were keel marked; 84·8, 35·5 and 15"7 per cent, respectively lambed. In season II, 98·4 per cent, 97·7 per cent and 95·7 per cent were keel marked and 95"4, 90·9 and 69·7 per cent respectively lambed. The performance of 93 Criolla ewes (a local breed) during season II is included in the report. INTRODUCTION

There are vast areas in the equatorial regions which offer considerable scope for the large-scale application of improved techniques of livestock production (McMeekan, I g6g). In many of these regions temperature per se is unlikely to depress fertility. Other components of the environment, particularly the photoperiod, could, on the other hand, have an intrinsic effect. Although considerable numbers have been exported to such areas this century there is a dearth of information concerning the fecundity of British breeds of sheep following their transfer to an equatorial environment. Anderson (cited by Yeates, I 965) has reported on the lowered reproductive efficiency of small groups of sheep imported into Kenya. For example, ten Border Leicester ewes failed to produce a lamb over a period of three years. Anderson (I964) has also drawn attention to the seasonal variation in the

* Present address:

c/o British Embassy, Bogota, Colombia. this address.

t Reprints available from

BRITISH VETERINARY JOURNAL, 127,

t

number of monthly lambings in data derived from flock books in Kenya over a period of 40 years (I92I - Ig6I). The seasonal peaks for lambing show a high month in April (2I·04 per cent) and a secondary one in October (I5·83 per cent), with a fairly even rise and fall between them. Where an equatorial photoperiod has been simulated under experimental conditions (Thwaites, I965), the evidence concerning the incidence of oestrus in the group suggests that flock management could become increasingly difficult, particularly in respect of concentrating lambings into a reasonable period. In Ig66 the Ministry of Overseas Development established a sheep management and craft centre at Pasto, in the province ofNarino, Colombia. Although Colombia has a predominantly agricultural economy the contribution of sheep is insignificant. The main purpose of the centre is to encourage both the improvement and expansion of the sheep industry. The potential of sheep production in Colombia has been outlined by Lumsden (Ig68). The British sheep attached to the centre represent several breeds and were, in the main, donated by the breeders of this country, largely due to the efforts of Dr E. Cresswell who carried out the initial survey in Colombia. Since their arrival at Pasto the sheep have been maintained at two separate locations forming two breed groupings, "mountain" and "lowland". It is convenient to adopt this sub-division in the presentation of this assessment of reproductive performance. CLIMATE

Pasto is approximately I oN and in a province where the climate is considered suitable for sheep originating from temperate zones. The annual rainfall of about 8oo mm. is fairly well distributed; April-May and October-November are usually slightly wetter than the rest of the year. The mean monthly temperature is in the range I 2-I 4 °C and in the period I g66-6g the mean total hours of sunshine per month was in the range 86-I I g hours. LOCATION, MANAGEMENT AND LIVESTOCK

The "Mountain" groups were kept at Granja Obonuco, Pasto, at an altitude of 3I00-36oo metres. The area allocated to the sheep was reclaimed scrub; the improved swards were dominated by volunteer Yorkshire Fog (Holcus lanatus) and white clover ( Trifolium repens). The ewes have been maintained on pasture alone since their arrival. The ewes were given access to proprietary mineral blocks containing o·o3 per cent potassium iodide until December, I g67. Symptoms of iodine deficiency appeared in the lambs of all breeds born in March-May Ig68. After lambing the mineral blocks were re-introduced and the ewes were given, in addition, a weekly drench containing 50 mg. KI. In November I967 the "Mountain" groups were made up of 66 Welsh Mountain, 45 Scottish Blackface and 70 North Country Cheviot ewes. There were three rams of each breed and no cross-breeding was undertaken in the imported groups. The majority of the Welsh Mountain ewes and 50 per cent

BRITISH MOUNTAIN SHEEP IN COLOMBIA

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of the Cheviot were pregnant at the time of importation; they lambed for the first time during March-April I967, shortly after their arrival inJanuary I967. The remaining 50 per cent of the Cheviot, and the Scottish Blackface ewes had been imported as empty hoggets. This report covers two breeding "seasons". In the first season the rams were re-introduced to their group on I8 October I967 and remained until 3I May I968. In the second season the rams were introduced on 24-]uly I968 and were withdrawn on 22 December I968. The rams were fitted with harnesses and the colour crayons were changed every I 7 days. Data from a group of 93 Criolla ewes, a local breed, were available for the second season and are included for comparative purposes. In the Welsh Mountain group, thirty ewe lambs were born during the March-April I967lambing. Information on their breeding performance during the second season is also included. PERFORMANCE

The general performance of the imported stock is summarized in Table I and illustrated in Fig. 1. It is very evident that considerable breed and season differences existed in terms of both ewes keel marked and ewes lambing. There was a marked improvement in the second season and ewes of two breeds, Welsh Mountain and Scottish Blackface, compared favourably with the performance of the local breed. The incidence of twinning in the second season was Welsh Mountain 6·6 per cent; Scottish Blackface I6·2 per cent; Cheviot 4-7·7 per cent and Criolla 2·0 per cent. There was a low incidence of "keel marking" and "lambing" in some of the groups; information on the incidence of keel marking and lambing according to I 7-day periods gives some indication of the level of activity and its spread. In Table II each service period is of I 7 days. The number of ewes keel marked TABLE I THE PERCENTAGE INCIDENCE OF KEEL MARKING AND LAMBING IN ALL BREEDS ( NUMBER OF ANIMALS IN BRACKETS )

Breed

Season I Rams in Oct. I8 I967-May 3I Ig68 No. of ewes Showing keel marks Lambing Season II Rams in July 24 rg68-Dec. 22 Ig68 No. of ewes Showing keel marks Lambing

Welsh

Scottish

Mountain

Blackface

66 8g·4 (59) 84·8 (56)

45 68·g (3I) 35"5 ( I6)

70 50"0 (35) I5"7 (II)

44

66 95"7 (63) 6g·7 (44)

97"7 (43) go·g (40)

Cheviot

Criolla

93 gi·4 (go) 84·9 (79)

BRITISH VETERINARY JOURNAL,

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I27, I

Season II

Season I 894 848

35·5 15·7

D ITITl

= 0

Keel marked

lim

Lambed

Welsh mountain

~-

Scottish blackface

Cheviot

illiiii

Criolla

Fig. t. The percentage of each breed group keel marked and the percentage of each group lambing in seasons I and II.

TABLE II PERCENTAGE OF ELIGIBLE EWES KEEL MARKED IN EACH SERVICE PERIOD

Season I Service period

Welsh Mountain

Scottish Blackface

Cheviot

0

0 26 50 33

0 3 23 34

2 3 4 5 6 7 8

II

40 ' 74 40 0 0 0 0 0 0 0 8

9

10 II

12 13 Season II Service period

Welsh Mountain I

2 3 4 5 6 7 8 9

7 37 68 37 43 36 50 45 57

9

9

0 0 0 3 0 0 0 0 Scottish Blackface 9

35 33 45 58 36 50 42 20

0 0 0 0 0

0 0

Cheviot

Criolla

22 32 27 26 41 27 34 36

44

9

55 53 31 56 57 10 23 6

BRITISH MOUNTAIN SHEEP IN COLOMBIA

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is given as a ~ercentage of all eligible ewes. The majority of matings occurred in four service periods in the first season whereas matings were spread over all nine periods in the second season. The percentage of ewes lambing to first service is shown in Table III. The percentage of Scottish Blackface and Cheviot ewes was markedly lower than that for the Welsh Mountain ewes in the first season; there was an appreciable improvement in the second season but breecl differences remained. The incidence of lambing according to I 7-day periods is given in Table IV, and illustrated in Fig. 2. A comparison between all periods and periods 1- 4

TABLE III EWES LAMBING TO FIR ST SERVICE

Total ewes 66

Season I

Welsh Mountain Scottish Blackface Cheviot

45 70

Season II Welsh Mountain Scottish Blackface Cheviot Criollo

65 44

66 93

Season I

84·8

No. ewes marked

59 31 35

No. lambing to first service 51 10

64 43 63 go

Percentage

II

86·44 32 "26 3 1"43

58 33 38 73

go·6 76•7 6o·3 81•1

Season II

846

83·3

530

All periods

Fig.

2.

Periods 1-4

Periods 1-4

[Sill

Welsh mountain

~ Scottish blackface

~

Cheviot

ITIIIIJ

Criolla

The incidence and distribution of lambing according to breed in seasons I and II.

TABLE IV INCIDENCE OF LAMBING IN SEASONS I & II

Season I Lambing Period*

Welsh Mountain (66) No. Percentage** I 2 3 4

0

Season II Lambing Period*

0

9 30 r6 (55)

13·6 45"5 24"2 (83·3)

I 56

r·5 84·8

---

Other periods All periods

Scottish Blackjace(45) No. Percentage 0

I 2 3 4

---

Other period All periods

I r6

* I7-day period commencing I 4 7 days from entry of ram.

0

0

2 4 2 (8)

2"9 5"7 2·9 (rr·5) 4"3 15"7

3 II

Cheviot (66) No. Percentage I0·6 7 21"2 14 !2•! 8 g·r (53·o) 6 (35)

---

--12 40

Cheviot (70) Percentage

---

2•2 35"5

Scottish Blackface (44) No. Percentage 6 13·6 20"5 9 6 13·6 7 (28) 15"9 (63· 6)

10·8 95"4

7 62

0

---

Welsh Mountain (65) Percentage No. 2 3"1 r8 27"7 44•6 29 9"2 (84·6) 6 (55)

No.

II·I 15·6 6·7 (33"4)

5 7 3 (r5 )

0>

II 46

27"3 go·g

!6•7 6g·7

Criolla (93) No. Percentage 31 33"3 r6·r 15 r6 17"2 6· 5 (68·8) 6 (64)

---

Ul

::r: ~ ~

ld ......

r6·r 84·9

15 79

~ ...... >-j ......

s

** Percentage of total ewes shown in brackets after breed.

e-. 0

c

TABLE V INCIDENCE OF LAMBING ACCORDING TO STATUS IN SEASON II (PERCENTAGE, WITH NUMBER IN BRACKETS)

Welsh Mountain

Lambing Period**

I 2 3 4

Scottish Blackface

Cheviot

Criolla (Colombian Stock)

E- L

E-0

S-0*

E-L

E-0

E-L

E-0

E-L

E-0

S-L

S-0

56

9

27

I6

28

IO

56

I2

36

9

36

I·8 (r) u·r (I) 23·2 (I3) 55·5 (5) 50"0 (28) II"I (I) o·o (o) 10"7 (6)

22"2 33"3 r8·5 o·o

(6) (g) (5) (o)

6·25 (I) r8·8 (3) o·o (o) I8·8 (3)

I8·o 21"4 25"0 I{"{

(5) (6) (7) (4)

o·o 20•0 Io·o o·o

(o) (2) ( I) (o)

12"5 (7) 21"4 (12) 12"5 (7) I0•7 (6)

8·3 o·o r6·7 o·o

(I) (o) (2) (o)

47"2 (I7) o·o (o) o·o (o) 19"4 (7) I9"4 (7) II•I ( I) 8·3 (3) I I·I (I)

36·I 22"2 I6·7 s-6

( I3) (8) (6) (2)

---------------------------------------------Periods I-4 85·8 (48) 77"7 (7) 74"I (20) 30"0 (3) 57"1 (32) 43"8 (7) 78·6 (22) 25"0 (3) 94"4 (34) 22"2 (2) 8o·6 (29) Other periods 10"7 (6) II•! (1) 22"2 (6) 40"0 (4) 12"5 (7) o·o (o) 33"3 (3) 37"5 (6) I8·o (5) 41"7 (5) 8·4 (3) ---------------------------------------------Total lambing g6·4 (54) 88·g (8) g6·3 (26) 8r·2 ( I3 ) g6·5 (27) 66·6 (8) 94"4 (34) 55·5 (5) 88·8 (32) 70•7 (7) 6g·6 (39) *Born at Pasto. •• 17-day period commencing 147 days following entry of ram. E-L =Ewes lambed previous lambing E-O = Barren previous lambing. S=Shearling.

~, ~

::-'

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inclusive shows that lambing was more compact during the first season. This is most apparent in the case of the Scottish Blackface ewes. The local ewes differed from the imported stock in that there was a high incidence of lambing during lambing period I. It can be seen from Table IV that the level of activity during the first service period was higher than in other breeds. This indicates that the incidence of oestrus was not related to the entry of the ram in a third of the Criolla group . Since ewes differed in their status at the start of the second season the presentation of the data in Table V is subdivided accordingly. Fifty-four Welsh Mountain ewes lambed (E-L) in two consecutive seasons. Their mean lambing date in the first season was 3 May; their mean lambing interval was 265 days. The mean lambing interval for I 3 Scottish Blackface and seven Cheviot ewes was 279 and 27 I days respectively. Twenty-seven Welsh Mountain shearlings born at Pas to in March I g67 also ran with the mature ewes during the second season. Twenty of them conceived during the first three service periods. The remaining three had conceived during the last service period of the first season and had lambed between 2 I October and 23 October Ig68. DISCUSSION

Where the usefulness of imported livestock kept as pure breeding groups is dependent on their multiplication rate, the prime objective is the attainment and maintenance of a high level offecundity. Management, owing to practical reasons, often imposes some restriction on the opportunity for its full expression and therefore the circumstances operating in the particular situation must be considered. In such circumstances the findings are not a reflection of reproductive capacity. 'Vhere there is marked seasonal variation in climate, and also in available herbage, the conventional management of a flock as one unit minimizes management problems. The periodicity of reproductive activity found in breeds kept in temperate areas allows the prediction of the onset of the breeding season throughout the flock. The re-entry of the ram may be timed so that lambing coincides with the beginning of the grazing season and also more favourable weather. The need for the synchronization of events is not necessarily so important in an envirorunent with no seasonal shortage of herbage; nevertheless the prevention of undue segregation of the flock could have its advantages. The presentation of this data allows an assessment of the ease of management based on the uniformity of behaviour in the various groups. Attention is drawn to the fact that rams were withdrawn from the groups for only eight weeks, 3 I May-24 July, between seasons, and therefore there was only moderate restriction on the opportunity to exhibit activity and to produce lambs. Observations of a subjective nature indicated that the behaviour of the rams was normal in both seasons and it is highly probable that the low incidence of oestrus in some of the groups in the first seasons was not the result of reduced libido in the male. Both sexes could have contributed to the very

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BRITISH VETERINARY JOURNAL, I27, I

unsatisfactory rate of lambing to first service in the Scottish Blackface and Cheviot groups. The cause of such a poor performance remains obscure and is the subject of further investigation. In the second season 30 Criolla ewes were run with both the Scottish Blackface and Cheviot groups. The behaviour and fertility of these Criolla ewes did not differ from those in their parent group mated pure. The performance of the Welsh Mountain shearlings in the second season is of considerable interest in that it allows a comparison between parent and offspring, and also the assessment of females which have been born into an environment with little or no fluctuation in the photoperiod. Only one sheading failed to lamb; the distribution of lambings was similar to the parent group. Beaty & Williams (I 970) compare the performance of two breeds of parent and offspring groups. There is sufficient evidence to inquire further into the influence of breed on performance in an alien environment. On the basis of these results the effect of an equatorial photoperiod and iodine deficiency on reproductive efficiency of various breeds warrants further investigation. ACKNOWLEDGMENTS

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

ANDERSON,]. (I964) . sth Int. Congr. Anim. Reprod. A.I., Trento, I964, 3· 46s. BEATY, T. & WILLIAMS, H. Ll. (I970). Br. vet.]., I26, vii. LuMSDEN, C. I. (I968) . Wld Crops, June, p. 28. McMEEKAN, C. P. ( I969). Anim. Prod., n, 271. THWAITES, C.]. (I965). ]. agric. Sci., Camb., 65, 57· YEATES, N. T. M. ( I965). Modern Aspects of Animal Production. London: Butterworth. (Accepted for publication 30 June I970)

La reproduction chez les races de :moutons britanniques en :milieu equatorial. I. Races des :rnontagnes (Beaty et Willia:rns) Resu:rne. Get article decrit !a reproduction chez 66 brebis des montagnes galloises, 45 "Blackface" ecossaises et 70 des Cheviots du Nord, pendant deux "saisons" d'elevage qui ont suivi leur arrivee a Pasta, en Colombie, debut I967. La saison I a commence le I8 Octobre I967 quand les beliers ont ete reintroduits dans le groupe de leur race. La saison II a commence le 24 J uillet I 968. Pendant !a saison I 89,4 pou_r cent, 68,9 pour cent et 50 pour cent des brebis des montagnes gal!oises, des "Blackface" d'Ecosse et des Cheviots, ont ete marquees a l'ocre rouge; 84,8 pour cent, 35,5 pour cent et I5,7 pour cent r espectivement ont agnele. Pendant !a saison II, 98,4 pour cent, 97,7 pour cent et 95,7 pour cent ont ete marquees a l'ocre rouge et 95.4 pour cent, 90,9 pour cent et 69,7 pour cent respectivement ont agnele. On a inc! us dans cette etude la reproduction de 93 brebis Criolla (une race locale) pendant !a saison II.

BRITISH MOUNTAI

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Die Reproduktion britisch geziichteter Schafe in aquatorialer Umgebung. I. Bergschafe (Beaty und Williams) Zusammenfassung. Beschrieben wird das reproduktive Verhalten von 66 wallisischen Bergschafen, 45 schottischen Blackface- und 70 Nord-Cheviot-Mutterschafen wahrend der Brunftperioden nach ihrer Aukunft in Pasta, Kolumbien, im Beginn des Jahres I967. Die erste Periode begann am I8 Oktober I967 als die Widder wieder zu ihrer Zuchtgruppe zugelassen wurden. Die zweite Periode begann am 24]uli I968. In der ersten Periode wurden 89,4 Prozent, 68,9 Prozent und 50 Prozen t der wallisischen Bergschafe, der schottischen Blackface und der Cheviot Mutterschafe mit Rote! gezeichnet; 84,8 Prozent, 35,5 Prozent und IS,7 Prozent lammten. In der zweiten Periode wurd en 98,4 Prozen t, 97,7 Prozent und 95,7 Prozent mit Rote! markiert und 95,4, 90,9 und 69,7 Prozent lammten. Das Verhalten von 93 Criollamutterschafen (eine ortliche Ztichtung) in der zweiten Periode wird ebenfalls berichtet. La actuaci6n reproductiva de castas britanicas de ovejas en un ambiente ecuatorial. I. Castas montaii.esas (Beaty y Williams) Resumen. Esta ponencia describe !a actuaci6n reproductiva de 66 ovejas Welsh Mountain, 45 Scottish Blackface y 70 North Country Cheviot durante dos "estaciones" de crianza, desde que llegaron a Pasta, Colombia, a principios de I967. La estaci6n numero I empez6 en el I8 de octubre de I967, cuando se volvieron a introducir a los moruecos a su grupo de casta. La segunda estaci6n empez6 en el 24 de julio de I 968 . En !a primera sesi6n, un 89,4 por ciento, 68,9 por ciento y so,o por ciento de las Welsh Mountain, Scottish Blackface y Cheviot fu eron criadas; 84,8 por ciento, 35,5 por ciento y I 5, 7 por ciento respectivamente produj eron cord eros. En !a segunda estaci6n, 98,4 por ciento, 97,7 por ciento y 95,7 por ciento fueron criadas y 95,4, go,9, 69,7 por ciento respectivamente produjeron corderos. Se incluye en el informe !a actuaci6n de 93 ovejas Criollas (una casta local) durante !a segunda estaci6n.