The North West Province (NWP) identified dairy farming as a priority as it has the potential, not only for job creation, but also as a sustainable source of high quality protein for rural communities. With the correct type of management systems, small-scale dairy farms have the potential to be economically feasible. For the purposes of this study, a small-scale dairy farm was defined as a farm which produced less than 500 litres of milk a day irrespective of the number of cows or size of the farm. The study area was Central North West Province and the study was a longitudinal observational study conducted with 15 small-scale dairy farmers from 2002-2006. Nutrition was found to be a major constraint to the production capacity of dairy cows studied. It was found that farmers were deficient in the knowledge, skills and experience required to develop an affordable and balanced feeding system based on locally available ingredients. Dairy rations were given to prevent malnutrition or starvation, rather than to increase production. It was also shown that feeding of the cattle on the farms investigated, was influenced more by availability and affordability of locally obtained feed ingredients than by planning nutrition to increase milk production. Available statistics show that there are approximately 257 000 dairy cattle in NWP, with the greatest numbers in the Central Region (175 235) and smaller numbers in the Western (59 852) and Eastern (21 873) Regions. These cattle produced approximately 230.4 million litres of milk annually (12.5% of national production) with an estimated value of R304.1 million at R1.32/l, excluding value-added products in the form of cheese, yoghurt, milk powder, and others in 2002. The method used was a longitudinal study conducted from 2002 to 2006 in three phases. In the first phase, situational analysis using participatory rural appraisal (PRA) and observation was used to outline the extent of the constraints and start to design appropriate interventions. Feeds used by the farmers for feeding dairy cows – both supplements and roughage - were tested and evaluated. In the second phase, three different feeding systems were designed from the data obtained from PRA, in consultation with small-scale dairy farmers, established commercial dairy farmers, state veterinary and agriculture staff, feed manufacturers and distributors and the commodity organization (MPO) to optimize the nutrition of the dairy cows. The third phase was field testing of interventions and observations of the implementation by farmers. It was found during the PRA phase that the majority (n=9) of farmers had been in dairy farming for not more than five years, five farmers had six to ten years in dairy farming and only one farmer had 11 to 15 years in dairy farming. Dairy farming is a very highly skilled operation and farmers need to have experience and knowledge to succeed. Five years is insufficient. Therefore capacity building and training were instituted over the period 2002 to 2005. Also, 60% (n=9) of the farmers were not affiliated to any agricultural organisation, so membership of the Milk Producers Organisation was facilitated for all farmers in the study. It was also found that the cattle were not identified and neither production nor financial records were kept. Testing and evaluation of feed used showed that it was of poor quality, deficient in protein, energy and minerals and no effort was made to balance the ration. In the second phase, three feeding systems were developed form data obtained and observations during phase one. These were A: a semi-intensive farm based ration using available crops, pastures and crop residues with minimal rations purchased; B: an intensive, zero-grazing dairy system using a total mixed ration (TMR) for farmers with smallholdings of less than 5 hectares per cow and C: Traditional, extensive or dual purpose system where the calf drank from the cow until weaning and milking was done only once a day, for farmers with more than 5 ha grazing available per cow. The last was a low-input/low output system and was implemented by a majority (n=8) of the farmers. System B was chosen by two farmers and not adopted by any of the two farmers in the long run. System A was adopted by three farmers. Four farmers left dairy farming for various reasons during the study. By July 2006, the farmers had changed to commercially formulated rations or licks and the body condition score of the cows had improved. Milk production per cow did not increase, but this may have been due to the increased price of meat and the fact that a majority of the farmers were using a dual purpose system and selling calves at weaning for a very good price. It was concluded that extension officers should get extra training in dairy if there are dairy farmers in their areas as this is a very specialist type of extension. They should also work closely with veterinary services including veterinarians, animal health technicians and the health inspectors. Further research should be done to optimise the traditional model as this is relatively profitable, has a lower risk and is less labour intensive. It is probably a good way to increase food security, particularly in families when only one or two members have an income from a pension or part-time employment. The prices realised from informal sales of milk and calves can give a stable income. The “community farms” should be economically evaluated in terms of each beneficiary being able to get a “living wage” out of the projected profits of the farm. The MPO and other stakeholders should give very specific training to new dairy farmers, based on the models that were used in this study. It is essential that framers be taught to “look forward” and get a pro-active attitude. They must also understand that quality, balanced rations are the key to success – poor rations are expensive rations, because they result in unhealthy cows and poor production. Finally, ongoing and effective monitoring and evaluation of extension is an effective instrument for project sustainability – farmers must be involved and participate in their own evaluation - extension is not all about paper work it is about measuring performance and good service delivery. / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2007. / Paraclinical Sciences / unrestricted

L'élevage de la chèvre « Baladi » au Liban souffre d'un problème de disponibilité alimentaire responsable des faibles performances établies de la race, du fait de sa dépendance majoritaire des zones de pâturage naturel et de la rareté des terrains fourragers ou de l'adoption du système intensif. Dans ce contexte agroclimatique particulier, cette étude se propose d'identifier la conduite optimale, à mi-chemin entre système extensif compromettant la production et la durabilité de l'élevage et système hors-sol qui ne saurait valoriser les aptitudes de la race et les parcours de la région. En effet, les conditions climatiques difficiles de la région d'étude impliquent l'insertion d'une dimension temporelle dans la conceptualisation de la conduite optimale, prenant en considération les fluctuations saisonnières non négligeables des ressources alimentaires naturelles. Comparée à la conduite extensive traditionnelle et à la complémentation largement moins adoptée, une conduite où les chèvres laitières seraient mises au pâturage durant les mois de printemps caractérisé par la prolifération des espèces végétales en vert et enfermées durant la sécheresse estivale paraît a priori adaptée aux conditions du milieu et aux objectifs zootechniques et socioéconomiques. Le cas échéant, le système intensif étant rarement prisé par les éleveurs de la région, l'efficacité des parcours à résidus agricoles ou fourragers aura également été évaluée afin de trouver un optimum zootechnique et économique. Par la suite, il a fallu mettre en place un outil d'évaluation des caractéristiques nutritives des parcours de la région d'étude, des quantités ingérées par les animaux lors du pâturage ou à l'auge et finalement de leur impact direct sur la production laitière et la satisfaction des besoins. L'évaluation des différentes conduites se reflétant dans un nombre de réponses en cours de lactation, un suivi d'analyse continu a été instauré permettant d'apprécier l'état corporel des animaux (poids, note d'état corporel, métabolites énergétiques), la production laitière (rendement, durée de lactation et composition du lait) et les performances reproductives (prolificité et croissance des chevreaux). Les capacités d'adaptation des animaux aux restrictions alimentaires dans les différentes conduites ont ainsi été testées. Ces expérimentations réalisées sur deux ans de suite ont montré que ces chèvres manifestent de réelles capacités adaptatives aux aléas alimentaires. En particulier, à chaque fois que l'alimentation le permet, l'énergie disponible est orientée préférentiellement vers la production laitière avec des rebonds relativement importants. Ces rebonds se produisent quel que soit le niveau de production laitière et pendant pratiquement toute la lactation. Parallèlement, on observe une reconstitution lente et régulière des réserves adipeuses qui s'accélère en fin de lactation à un moment où les femelles sont généralement mises à la reproduction, alors que les productions laitières baissent inexorablement. Cette thèse a donc abouti à l'acquisition de connaissances originales sur un modèle animal peu étudié caractérisé par des capacités adaptatives remarquables qui ne se manifestent pas de façon aussi marquée chez les chèvres sélectionnées des zones tempérées / Adaptives capacities of Baladi goats fed on semi-arid rangelands of Bekaa valley (Lebanon)ABSTRACTThe Lebanese Baladi goat dairy production sector suffers from a problem of food availability which is responsible of the animal's poor performances, due to its dependence towards natural rangelands and the scarcity of crop residues and forage pastures as well as of the adoption of intensive systems.In this particular agroclimatic context, this study aims to identify the optimal conduct for this goat, half-way between an extensive system where production and durability are compromised and an intense one where the aptitudes of the breed and the variety of the region's pastures are not valorized. In fact, the region's difficult climatic conditions require the insertion of a temporal dimension in the conceptualization of the optimal conduct, considering the important seasonal fluctuations of the natural feed resources. Compared to the traditional extensive conduct and to the much less adopted supplementation, a conduct where the goats were pasture driven during the spring characterized by the proliferation of green plants and kept indoors during the summer season seems a priori adapted to the local conditions and to the technical and economic objectives. However, the intensive system being rarely considered by the local farmers, the efficiency of agricultural pastures such as crop residues and forages would also have been tested in order to find an optimum between production and feasibility. Thus, an evaluation tool of the pastures' nutrition values, the quantities ingested by the animals during grazing and indoors and finally of their impact on the milk production and satisfaction of feed requirements was implemented. The evaluation of the different tested conducts were reflected on a number of physiological responses during lactation such as the animals' body reserves (body weight, body condition score, NEFA), milk production (quantities, duration and milk composition: milk fat and milk protein contents) and reproductive performances (kids' number, birth weights and growth). The animals' adaptive capacities to different food restrictions situations are hence here tested.These trials realized on two subsequent years showed that this breed demonstrates clear adaptive capacities facing feed fluctuations. A particular adaptation is the orientation of the available extra energy towards milk production with relatively important rebounds whenever allowed by refeeding. These rebounds occurred whatever the initial milk production level and during practically the whole lactation period. In parallel, we observed a slow and regular reconstitution of the body reserves which accelerates at the end of lactation, when the females are getting ready for reproduction, while the milk production suddenly breaks down. In consequent, this study has collaborated in acquiring new original information about an original animal breed characterized by special adaptive capacities which don't generally show in selected high production breeds.Kewords : Baladi goat, feeding conduct, pasture, indoors, adaptive capacities, feeding behaviour, body reserves, milk production, reproductive performances

La lipolyse est une réaction enzymatique qui influence négativement les qualités organoleptiques et technologiques du lait. La lipolyse spontanée (LS) correspond à la part de la lipolyse qui dépend de l’animal et du système d’élevage. La LS résulte de l’action de la lipoprotéine lipase (LPL) et de ses cofacteurs sur les globules gras (GG). L’objectif de la thèse a été de comprendre les variations de LS à l’échelle zootechnique et à l’échelle du lait. Les vaches (VL) ont pu être classées en 2 groupes selon leur phénotype : « susceptible » et « non susceptible » à la LS, confirmant l’importance de l’effet individu. Chez les VL susceptibles, nous avons confirmé un effet de la race/génétique, de la parité, du stade physiologique, du moment de la traite, de la fréquence de traite et de l’alimentation.La LS était plus élevée dans les laits issus de la traite du soir, chez les VL Holstein, génotypées KK au locus de DGAT-1. Elle l’était également en fin de lactation et en début de lactation uniquement chez les multipares hautes productrices. Un bilan énergétique négatif pourrait expliquer ces variations. L’augmentation de la fréquence de traite, la restriction alimentaire, l’alimentation à base d’ensilage de maïs comparé à l’herbe conservée/fraîche et la supplémentation lipidique ont également augmenté la LS. Le mécanisme d’action implique probablement une inhibition de la LS par la protéose peptone 5. La membrane des GG semblerait avoir un rôle crucial dans le maintien de l’intégrité du GG, l’interaction avec la LPL et l’équilibre des cofacteurs. L’impact des facteurs zootechniq / Lipolysis is an enzymatic reaction which leads to off-flavor in milk and impairs technological properties of milk. Spontaneous lipolysis (SL) is the fraction of lipolysis which depends on cows and breeding systems. SP corresponds to the hydrolysis of milk fat in milk fat globules (MFG) by the lipoprotein lipase (LPL) and its cofactors. The aim of the PhD was to understand SL variations at both zootechnical and biochemical levels. Cows were sorted in two groups according their phenotype: “susceptible” and “non-susceptible” to SL, confirming the strong impact of the individual effect. Among cows “susceptible” to SL, we confirmed the effects of breed/genetics, parity, physiological stage, milking moment, milking frequency and feeding systems. SL was higher in evening milks of Holstein cows and of cows having the KK genotype at the DGAT-1 locus. SL was higher in late lactation and, in early lactation only for high merit multiparous cows, probably in relation to negative energy balanceAn increase in milking frequency, feeding restriction, maize silage based diets compared to fresh grass and conserved grass based diets and lipid supplementation enhanced SL. At a biochemical level, LS might be inhibited by proteose peptone 5. The MFG membrane might play an important role on MFG integrity, LPL and MFG interactions, and cofactors balance. The impact of zootechnical and biochemical factors on SL is still difficult to hierarchize