Camel milk plays a central role in the food supply of Eastern African and Middle Eastern countries (e.g. Kenya, Somalia, Saudi, and Ethiopia), home to the majority of the world’s camel population. Raw, and traditionally fermented camel milk has become increasingly commercialised and consumed in urban areas. This has led to an increased interest in the processing of camel milk for the urban market, with skimmed camel milk casein and whey powders soon to be commercialised, in a manner similar to the already widely available bovine dairy powders. However, little information is currently available concerning the effects of different processing methods (e.g. thermal treatment) on camel milk fractions. Currently there are no camel milk derived products, such as yoghurt or cheese, available in local Saudi supermarkets. Furthermore, the abundance of bioactive substances in camel milk have been reported to have useful effects; one of the most prominent is the anti-diabetic benefits revealed by in vivo studies. However, the presence of insulin in camel milk still remains to be proven. The aims of this thesis are twofold. The first area (Chapters 2, 3 and 4) describe the effect of heat treatment on camel milk components and their functional properties in an oil and water emulsion, and in yoghurt. In order to test these functional properties, camel skimmed milk, whey and casein were prepared and freeze dried. The key novel findings include: skimmed milk that had been heat treated and freeze dried showed significantly improved functionality for use in emulsions and yoghurts, whereas heat treated whey did showed no significantly enhanced functional properties. Furthermore, non-heated freeze dried casein significantly enhanced curd formation in yoghurt, and resulted in a smooth texture. Two fermented yoghurts were developed containing heat treated skimmed milk powder or casein with similar textural properties to bovine milk commercial yoghurt, that were acceptable in taste and texture, as determined by an independent study for sensory evaluation. The second area of this study (Chapter 5) concerned the characterisation of insulin in camel milk. As it was confirmed by previous studies that the presence of high concentration of insulin in camel milk comparing to bovine milk. Key findings were that no protein with a characteristic molecular weight similar to bovine or human insulin (5.8 KDa) could be detected using Western Blotting; however, a 62 KDa protein showed consistent immune reactivity. ELISA results showed high immune reactivity in camel whey. An in vivo assay showed biological insulin like activity in camel milk, but the validity of the assay still needs to be confirmed.

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It has been shown that a typical source of camel milk in Jordan contains 123g l-1 total solids, of which around 27g is protein, 30g fat, 39g lactose and 8.2g ash. More detailed analyses revealed much higher levels of vitamin C (33mg l-1) and iron (4.1mg l-1) than for bovine milk. Seasonal variations were noted, and these were associated with the availability of drinking water and changes in the plant flora on which the camels were grazing. The low level of protein in camel milk (compared to bovine milk) and the chemical nature of the caseins means that, in the past, the milk was neither fermented to yoghurt nor used as a base for a semi-hard/hard cheese. However, in this study, a Nabulsi cheese was produced that had the same chemical composition as the commercial cheese made from bovine milk. The camel milk cheese was also acceptable to a taste panel. As the camels were hand milked with poor hygiene during this project, total colony counts in the raw milk were usually in the region of 1.0 x 106 colony-forming units (cfu) ml-1. Such counts make the milk unsuitable for retail sale, and hence a small pasteurising plant was established. By applying Hazard Analysis and Critical Control Point system (HACCP) principles to the operation, pasteurised milk with counts of 1.1 x 103 cfu ml-1 was obtained. It is hoped that the success of this plant will encourage other dairies in Jordan to employ HACCP correctly to raise the microbial quality of their products; a survey of three dairies in Jordan showed that, although they were claiming to apply HACCP programmes, many aspects of product safety were overlooked.

A series of studies were conducted to investigate the effects of dietary energy and protein supply on behaviour and fertility in the modem high yielding dairy cow. The results demonstrate few direct dietary treatment effects on reproductive perform'ance. However, dietary strategies which alleviate severe negative energy balance in the early post partum period are beneficial to reproductive performance. A more positive energy balance in early lactation was associated with improved ovarian function, namely; earlier commencement to luteal activity, and improved luteal function (essential for embryonic development). In addition, there was a suggestion that a restricted energy allowance in the pre-calving period. could prove beneficial' to fertility in the post-calving period. Significant associations between average daily energy balance and a number of behavioural activities suggests that monitoring of animal behaviour may be a useful indicator of energy imbalance. In particular, standing ruminating in the two hour period post evening milking was strongly negatively correlated with daily energy balance. The expression of this particular behaviour is likely to be a response to stress (displacement behaviour). Oestrous behaviour appears to be unaffected by dietary protein level. The most influential factor on the expression of oestrus was the size of the sexually active group. Multiple cows cycling together appear to produce more intense oestrous cycles with an increased expression of standing immobile on being mounted. Despite being t~e most accurate oestrous behaviour, standing immobile on being mounted was only expressed in 52% of oestrous cycles, making it less useful in oestrous detection. The importance of secondary be~aviours, such as mounting or attempting to mount another cow has been highlighted. Mounting or attempting to mount another cow had a high rate of expression and, when expressed, a high proportion of animals were in oestrus. This behaviour was identified as being the most reliable sign of oestrus.