Correlation between weight and BCS of Ouled Djellal ewes in an accelerated lambing farm

S Smaali

Faculty of Exact Sciences and Sciences of Nature and Life, Larbi Tebessi University, Tebessa, Algeria
sss.smaali@gmail.com

Abstract

This work was being carried out in order to study the correlation between weight and body condition at control period (mating), lambing and 30 days later in Ouled Djellal ewes to find out which period is the most important to coincide with periods of higher natural forage supply. The study involved 22 Ouled Djellal ewes bred in an accelerated lambing system (3 lambing in 2 years) during 2 reproduction cycles, from april 2017 to july 2018 (16 months). The combined weight (W) and body condition score (BCS) of the ewes was carried out every month. The results showed a positive correlation between the BCS at control and lambing (R=0.28) and between the BCS at lambing and 30 days later (R=0.70). Similarly, there was a positive correlation between the weight at control period and lambing (R=0.57), as well as between the weight at control period and 30 days after lambing (R=0.60). In an accelerated system, it is important to coincide the control period with spring season when natural forage resources are available.

Key words: accelerated lambing system, body condition score, lambing, mating, reproduction

Etude des corrélations entre le PV et NEC de brebis Ouled Djellal, dans un élevage à rythme d’agnelage accéléré

Résumé

Ce travail a été réalisé pour étudier la corrélation entre le poids et l’état corporel à la lutte, à la mise bas et 30 jours après, chez des brebis de race Ouled Djellal, ceci pour savoir quelle est la phase la plus importante afin de la faire coïncider avec les périodes où l’offre fourragère naturelle est plus forte. L’étude a concerné 22 antenaises de race Ouled Djellal élevées dans un système d’agnelage accéléré (3 agnelages en 2 ans) pendant 2 cycles de reproduction, d’avril 2017 à juillet 2018 (16 mois). La pesée et la notation corporelle des brebis, ont été réalisées chaque mois.

Les résultats ont montré une corrélation positive : entre la NEC à la lutte et à la mise bas (R=0,28) et entre la NEC à la mise bas et 30 jours après (R=0,70). De même, il existe une corrélation positive entre le PV à la lutte et le PV à la mise bas (R=0,57), ainsi qu’entre le PV à la lutte et le PV 30 jours après mise bas (R= 0,60). En système accéléré, il est important de faire coïncider la lutte avec la saison de printemps où les ressources fourragères naturelles sont disponibles.

Mots clés: agnelage, corrélation, lutte, mise bas, note état corporel, poids vif, reproduction, système d’agnelage accéléré

Introduction

During their reproductive cycle, the physiological state of the ewes corresponds to different dietary requirements, hence the need to adopt a feeding strategy that ensures the adequacy between nutritional needs and dietary intakes to have animals in a correct body condition. This work was carried out in order to study the correlation between weight and body condition during control period (mating), lambing and 30 days later in Ouled Djellal ewes to find out which phase is the most important to coincide with the periods when the natural forage supply is higher (spring).

Materials and methods

The study involved 22 Ouled Djellal ewes bred in an accelerated lambing system (3 lambing in 2 years). The diet is based on steppe meadows and cereal stubble. A concentrated feeding supplement of 400 - 500 g/head/day was given for a total of 1 month, before and after the fight (flushing) and one month before the planned lambing (steaming).

The combined weighing and body assessment of the ewes was carried out every month. Body scoring was performed using the technique of Russel et al. (1969), with a score of 0 to 5. The determination of averages (Av.), standard deviation (SD), correlation coefficient and variance coefficient (VC) was performed using IBM SPSS software (version 24, 2015 for MAC).

Results and discussion

In two years of follow-up, there were 3 periods of control and 3 periods of lambing, with 68 births and 82 lambs born, of which 9 lambs died at birth. The average lambing was 1.42 ± 0.19 lambing per ewe per year with an average of 1.52 ± 0.65 lambs per ewe per year. The study of the relationship between the BCS at control, calving and 30 days after calving showed a positive correlation; between the BCS at control and calving (R=0.28) and between the BCS at calving and 30 days later (R=0.70).

Similarly, there was a positive correlation between control period and lambing weight (R=0.57), as well as between control period and 30 day after lambing W (R=0.60) (Table 2).

Weighing and BCS are the most commonly used methods to evaluate the feeding behavior of a herd. However, there is no direct link between the BCS and the animal's ticket (Froment 2007). The score evaluates a fattening status: two animals of very different weights may have the same score. The genotypic correlation of BCS at key moments is negative (Dechow et al., 2002).

An insufficient body condition score during control indicates the need to improve the feed ration for storing lipids that will be later used (Guesent and Demarene, 1987).

Conclusion

• In an accelerated system, given the impact of the BCS of ewes on lamb growth and the correlations between BCSs at different stages, it is important to coincide the mating season with spring  when natural forage resources are high.

Acknowledgements

The results of the experiment described in this paper were presented at the 24^th Meeting on Ruminant Research 5-6 December 2018, Paris - Versailles, Quae ed.

References

Dechow C D, Rogers G W and Clay J S 2002 Heritability and correlation among body condition score loss, body condition score, production and reproductive performance. J Dairy Sci, 85: p. 3062-3070.

Froment P 2007 Note d’état corporel et reproduction chez la vache laitière. Thèse de doctorat vétérinaire. ENV Alfort. 112 p.

Guesent P H and Demarne Y 1987 La régulation de la lipogenèse et de la lipolyse chez les mammifères. INRA Edition, Paris. 128 p.

Russel A J F, Doney J M and Gunn R G 1969 Subjective assessment of body fat in live sheep. J. Agric. Sci. 72: p 451-454.

Received 27 December 2018; Accepted 23 February 2019; Published 1 April 2019

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