Milk from the cow is one of the most versatile and important substances in the human diet as well as in the diets of many animals and in particular in the diet of poultry that are being raised as layers, broilers or for other purposes. The fact that this milk can be processed into many different forms adds to its versatility and provides a wide array of by-products from which specialized uses can be determined. Understanding the basic array of materials that can be obtained from processing milk is the first step in understanding how those products can be used in the diets of poultry. The next step of understanding the relationship between dairy by-products and the benefits they can provide to poultry comes through examining the nutritional content of those by-products for the feeding and development of poultry. As these two explanations are provided it becomes evident in which ways poultry diets can be supplemented with the milk by-products and to examine further benefits to poultry health that can be achieved through medicinal application of milk products.
The major goals of this paper are designed to explore and examine the relationship of milk processing for the formation of cheese and other by-products to the diets of poultry. To accomplish the goals it will be useful to analyze several different concepts that are interrelated and in many ways interdependent. The first goal is to provide a comprehensive overview of milk by-products that are derived primarily from the production of cheese. In addition, it is necessary to identify the general nutrient contents of milk by-products specifically as it relates to those ingredients most beneficial to poultry development. Third, the manner in which these by-products can be utilized as feedstuff or as supplements for poultry diets is included in the analysis. As a function of this analysis it will be clear which components of the milk by-products can be applied in poultry diets for health maintenance and promotion. Ultimately, the goal of the paper is to provide a complete overview of milk by-products and their use in poultry diets.
Prior to engaging in any analysis of milk processing and the resulting by-products that are produced it is useful to describe nutritional considerations related to developing poultry. "The ability to convert nutrients to the final products depends on a variety of external and internal factors, such as age, sex, genetic background and housing system." (Pishnamazi et al. 163) These factors are important to keep in mind especially considering that the vast majority of developmental problems that occur among farm animals happen in the poultry area and can therefore be influenced by many things. One reason for developmental problems in poultry has to do with nutritional deficiencies that occur out of ignorance, illness or neglect. Thus, the study of nutritional needs and the corresponding nutrient makeup of poultry foodstuffs should be of major importance to anyone involved in raising these types of birds.
Poultry development requires a significant amount of energy and the correct nutrients to progress properly. For example, Zinc is an important micronutrient that can cause growth retardation when lacking in quantities. Like many nutritional substances, zinc has a relationship to the overall health of the birds and quantities required may vary based on other dietary inputs. Another example of critical nutritional components for the proper development of poultry is protein. Protein is essential because of its role in providing structure and form to virtually every cell. Protein is the foundation of good health and is used in a variety of bodily functions. Providing proper amounts and types of protein are of paramount importance for the quality of the poultry that is developed. Some of the other important nutrients that poultrymen are concerned with assuring are present and in the correct quantity are calcium, phosphorus and cholecalciferol. Each of these nutrients must be provided in the proper ratio to assure proper health and development.
Because of milk's amazing ability to meet the nutritional needs of animals it has become extremely attractive to use as feed. However, because of the costs involved relative to other sources of feed, milk is often reserved for only the youngest animals. In addition, fresh milk products are often unwieldy and extremely difficult to easily distribute which, when considering how quickly they deteriorate during transport makes them even less attractive as a long-term food source. There are also nutrition considerations that must be taken into account when considering milk and milk by-products as feed. Milk is low in iron and copper making the animals that rely on it as their primary or only food source susceptible to many illnesses and/or deficiencies. One such deficiency that can be caused by the absence of important minerals is anemia which is manifested by the colorless nature of what is often referred to as white veal. When this condition is present, it is often the result of calves that have been fed almost entirely on milk that has not been fortified with the necessary micronutrients. Nevertheless, fresh milk and milk by-products can be used in a number of ways in the raising of broilers, layers and turkeys because of the many benefits that they provide. This section of the paper includes some of the processes by which milk by-products are generated during the production of cheese and provides a brief description of each by-product discussed.
Milk Preparation Precedes Cheese Manufacturing
Depending on the type of cheese being produced as well as the other by-products that are being sought by the manufacturer, the milk is separated into whole milk, semi-skimmed milk and skimmed milk. This is accomplished by placing the milk in a centrifugal separator which divides lighter fatty phase materials from the non-fat matter. Once the milk is prepared at the level of fat content that the manufacturer desires, the milk is homogenized to prevent the material from separating into its constituent parts.
Prior to processing milk into cheese there are a number of steps that must be taken to assure that the milk being used is pure and free of contaminants. To assure that milk is adequately prepared for cheese manufacturing the product must be heat treated. Heat treatments include pasteurization, sterilization and ultra heat treatment or UHT. Milk pasteurization is done to kill bacteria by heating the liquid at 74°C for fifteen seconds. This level of pasteurization is commonly called low temperature pasteurization and while it kills harmful organisms the process also inactivates some enzymes but allows other enzymes to remain active. High temperature pasteurization and ultra high temperature (UHT) pasteurization heat at 90°C for fifteen seconds and 145°C for fifteen seconds respectively and sterilizes the milk completely but also causes progressive deactivation of more enzymes. Once the milk has been sterilized, it is ready for further processing.
Several milk products and by-products are produced as a function of processing whole milk. Some of these components are extremely useful to include in poultry feed as will be discussed below. The major components in milk are water, lactose, fat, protein, minerals and other components that are particularly important in relation to helping maintain proper health for the animals. Lactose is the major sugar or carbohydrate in milk and is composed of glucose and galactose. The fat in milk is for the most part triglicerides and is a powerful source of energy which meat birds demand in order to develop appropriately. There are different types of proteins available in milk and are referred to as whey or casein. These proteins contain important amino acids that are building blocks for the physical material of the birds and must be a part of the diet whether milk by-products are used or other feedstuff is provided. Milk has a significant amount of calcium and phosphorus that are important for skeletal formations as well as many physiological functions. These and other compounds found in milk by-products are very attractive for use in a developing animal but understanding how to get to the separate components requires a look at the cheese manufacturing process.
Cheese Manufacturing and Milk By-Product Production
Cheese manufacturing can be divided into four main steps. It is possible to organize the work done under different headings and into slightly different components but for the purpose of this explanation the process has been divided into coagulating, draining, salting and ripening. Prior to the actual manufacturing process and during the process, various milk by-products can be derived.
'Cheesemaking begins with the application of proteolytic enzymes that coagulate milk to form curds." (Burrington) Coagulation of milk is allowed to begin the process of converting milk into cheese. Coagulation is another word for clotting and describes the physical and chemical changes that take place in the milk which causes the separation of the milk or what is referred to as the curd from the liquid component or what is referred to as whey. The coagulation process also includes the introduction of a bacterial component. The bacteria that are used are not harmful to…