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Evaluation of crude annual parturition rate estimates in a small-holder African ruminant farming system

  • M. Lesnoff (a1) and R. Lancelot (a1)

Abstract

Many parameters have been proposed for evaluating livestock reproduction performances in tropical farming systems. In tropical free-ranged and small-holder systems, where reproduction cycles cannot be individually observed without expensive field surveys, one of these parameters is the average number of parturitions (h) expected by reproductive female, if the female spends the whole year in the herd. A frequent approach for estimating h is to use the ratio hc = m/T, so-called ‘crude annual parturition rate’, where m is the observed number of parturitions and T is the total time of presence of the reproductive females in the herd during the year. The bias encountered when h is estimated by hc was evaluated in this paper. Six methods of estimation were used, where T was the exact observed time of presence (hc1) or approximated by monthly, quarterly, half-yearly and yearly averages or final size of the reproductive herd size (hc2 to hc6). Data came from long-term follow-up of cattle and small-ruminant herds (with data recorded at animal level) in extensive agro-pastoral systems in Senegal. In general, h was correctly estimated by hc1. Nevertheless hc1 was sensitive to competing risks (e.g. deaths, sales and slaughtering of reproductive females) and was seriously biased when intensive withdrawals of females occurred before or during the parturition peak. Reliability of crude rates progressively decreased from hc2 to hc6, corresponding to the degradation of information used for approximating T. This decrease was much lower for cattle (for which all methods had acceptable reliability) than for small ruminants. Among the compared methods, the lower reliability was observed for hc6 that we do not recommend for small ruminants. Methods hc5 and hc6 are currently used in rapid cross-sectional retrospective surveys based on the recall of the farmers on the demographic events which occurred in the herd over the last past 12 months. The study has showed that such surveys and estimates hc5 and hc6 can generate seriously biased results. More globally, annual parturition rates can be highly variable depending on the 12-month periods considered. Annual parturition rates estimated on short-term data, even with precise herd follow-up surveys, must be considered cautiously.

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Agresti, A 1990. Categorical data analysis. Wiley, New York.
Bebe, BO, Udo, HMJ, Rowlands, GJ, Thorpe, W 2003. Smallholder dairy systems in the Kenya highlands: cattle population dynamics under increasing intensification. Livestock Production Science 82, 211221.
Berthet-Bondet, J, Bonnemaire, J 1986. L’élevage dans une agriculture en terrasses des hautes collines himalayennes: Salmé au Népal. Cahiers de la Recherche Développement 9–10, 121132.
Chiang, CL 1984. The life table and its application. Robert E. Krieger Publishing Company, Malabar, Florida, USA.
CIRAD-IEMVT 1989. Les enquêtes sur la productivité du bétail. Fiche Technique no 5. CIRAD-IEMVT (Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Institut d’Elevage et de Médecine Vétérinaire des pays Tropicaux), Maisons-Alfort, France.
Clément, V, Poivey, JP, Faugère, O, Tillard, E, Lancelot, R, Gueye, A, Richard, D, Bibé, B 1997. Etude de la variabilité des caractères de reproduction chez les petits ruminants en milieu d’élevage traditionnel au Sénégal. Revue d’Elevage et de Médecine vétérinaire des Pays Tropicaux 50, 235249.
Collett, D 2003. Modelling survival data in medical research. Chapman & Hall/CRC, New York, USA.
Ezanno, P, Ickowicz, A, Bocquier, F 2003. Factors affecting the body condition score of N’Dama cows under extensive range management in Southern Senegal. Animal Research 52, 3748.
Faugère, O, Dockes, AC, Perrot, C, Faugère, B 1990a. L’élevage traditionnel des petits ruminants au Sénégal. I. Pratiques de conduite et d’exploitation des animaux chez les éleveurs de la région de Kolda. Revue d’Elevage et de Médecine vétérinaire des Pays Tropicaux 43, 249259.
Faugère, O, Dockes, AC, Perrot, C, Faugère, B 1990b. L’élevage traditionnel des petits ruminants au Sénégal. II. Pratiques de conduite et d’exploitation des animaux chez les éleveurs de la région de Louga. Revue d’Elevage et de Médecine vétérinaire des Pays Tropicaux 43, 261273.
Faugère, O, Faugère, B 1986. Suivi de troupeaux et contrôle de performances individuelles des petits ruminants en milieu traditionnel africain. Aspects méthodologiques. Revue d’Elevage et de Médecine vétérinaire des Pays Tropicaux 39, 2940.
Faugère, O, Merlin, P, Faugère, B 1991. Méthodologie d’évaluation de la santé et de la productivité des petits ruminants en Afrique: l’exemple du Sénégal. Revue scientifique et technique (International Office of Epizootics) 10, 103130.
Huttner, K, Leidl, K, Pfeiffer, D, Kasambara, D, Jere, FBD 2001. The effect of a community-based animal health service programme on livestock mortality, off-take and selected husbandry applications. A field study in northern Malawi. Livestock Production Science 72, 263278.
Ickowicz, A, Mbaye, M 2001. Sudanian forest and cattle feeding in Senegal: potential and limits. Bois et Forêts des Tropiques 270, 4761.
ILCA 1990. Livestock systems research manual. Working Paper 1, Vol. 1. ILCA (International Livestock Centre for Africa), Addis Ababa, Ethiopia.
Juanès, X, Lancelot, R 1999. LASER: logiciel d’aide au suivi d’élevages de ruminants. CIRAD, Département EMVT, Montpellier, France.
Kalbfleisch, JD, Prentice, RL 1980. The statistical analysis of failure time data. Wiley, New York, USA.
van Klink, EGM, Corten, JJFM, Kalonoki, DM 1996. Herd monitoring in traditional cattle husbandry as a tool for productivity research and livestock development. Tropical Animal Health and Production 28, 273279.
Laird, N, Olivier, D 1981. Covariance analysis of censored survival data using log-linear analysis techniques. Journal of the American Statistical Association 76, 231240.
Lancelot, R, Lesnoff, M, Tillard, E, McDermott, JJ 2000. Graphical approaches to support the analysis of linear multilevel models of lambs pre-weaning growth in Kolda (Senegal). Preventive Veterinary Medicine 46, 225247.
Landais, E, Sissokho, MM 1986. Bases méthodologiques du contrôle des performances animales pour l’analyse zootechnique et démographique: collecte des données et choix des variables. In Méthodes pour la recherche sur les systèmes d’élevage en Afrique intertropicale. Etudes et synthèses no 20 (ed. E Landais), pp. 433485. CIRAD-IEMVT (Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Institut d’Elevage et de Médecine Vétérinaire des pays Tropicaux), Maisons-Alfort, France.
de Leeuw, PN, McDermott, JJ, Lebbie, SHB 1995. Monitoring of livestock health and production in sub-Saharan Africa. Preventive Veterinary Medicine 25, 195212.
Lesnoff, M 1999. Dynamics of a sheep population in a sahelian area (Ndiagne district in Senegal): a periodic matrix model. Agricultural Systems 61, 207221.
Lesnoff, M, Saley, M, Adamou, K, N’Djafa Ouaga, H, Ayantunde, A, Gérard, B 2008. 12MO: a retrospective method for estimating demographic parameters in tropical ruminant livestock populations. CIRAD (French Agricultural Research Centre for International Development), Montpellier, France; ILRI (International Livestock Research Institute), Nairobi, Kenya.
Lhoste, P, Dollé, V, Rousseau, J, Soltner, D 1993. Manuel de zootechnie des régions chaudes – Les systèmes d’élevage. Ministère de la Coopération, Collection Précis d’Elevage, Paris, France.
Madani, T, Hubert, B, Vissac, B, Casabianca, F 2002. Analyse de l’activité d’élevage bovin et transformation des systèmes de production en situation sylvopastorale algérienne. Revue d’Elevage et de Médecine vétérinaire des Pays Tropicaux 55, 197209.
Marzin, J, Liénard, G 1984. Productivité en agneaux des troupeaux ovins. Réflexions sur le choix d’une méthode d’analyse. Bulletin Technique du Centre de Recherches Zootechniques et Vétérinaires de Theix, INRA 56, 69–90.
Metz, T, Asfaw, MD 1999. LIMS: database for livestock performance data. Version 1.2. Computer program with system documentation. ILRI, Nairobi, Kenya.
Mukasa-Mugerwa, E 1989. A review of reproductive performance of female Bos Indicus (zebu) cattle. ILCA monograph no 6, International Livestock Centre for Africa, Addis Ababa.
Planchenault, D 1991. Survey on the productivity of livestock in cameroon. Manual for investigators. CIRAD-IEMVT (Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Institut d’Elevage et de Médecine Vétérinaire des pays Tropicaux), Maisons-Alfort, France.
Poivey, JP, Seitz, JL, Landais, E 1981. Finalités et aspects méthodologiques d’un système informatisé de suivi individuel des animaux dans les élevages bovins villageois du Nord de la Côte d’Ivoire. Revue d’Elevage et de Médecine vétérinaire des Pays Tropicaux 34, 199210.
Prentice, RL, Kalbfleisch, JD 1978. The analysis of failure times in the presence of competing risks. Biometrics 34, 541554.
SEDES 1975. Etude de la structure et de la dynamique des troupeaux bovins: méthodologie pratique. Ministère de la Coopération, Paris, France.
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