Text 16. MILKING CYCLE OF COWS

Milk is a source of nutrients and immunological protection for the young cow. The gestation period for the female cow is 9 months. Shortly before calving, milk is secreted into the udder in preparation for the new born. At parturition, fluid from the mammary gland known as colostrum is secreted. This yellowish coloured, salty liquid has very high serum protein content and provides antibodies to help protect the newborn until its own immune system is established. Within 72 hours, the composition of colostrum returns to that of fresh milk, allowing to be used in the food supply.

The period of lactation, or milk production, then continues for an average of 305 days, producing as much as 9000 or more kg of milk. This is quite a large amount considering the calf only needs about 1000 kg for growth.

Within the lactation, the highest yield is 2-3 months post-parturition, yielding 40-50 L/day. Within the milking lifetime, a cow reaches a peak in production about her third lactation, but can be kept in production for 5-6 lactations if the yield is still good.

About 1-2 months after calving, the cow begins to come into heat again. She is usually inseminated about 3 months after calving so as to come into a yearly calving cycle. Heifers are normally first inseminated at 15 months so she's 2 when the first calf is born. About 60 days before the next calving, the cow is dried off. There is no milking during this stage for two reasons: milk has tapered off because of maternal needs of the fetus; udder needs time to prepare for the next milking cycle.

Text 17. BREEDS OF POULTRY

Breeds had become grouped according to area of origin — American, Asiatic, British, French, and Italian — and they were divided into varieties characterized by a particular color or color pattern or comb type.

The interest in poultry was almost exclusively in achieving perfection of show specimens. Little attention was paid to productivity in eggs or meat.

The breeds which currently dominate world production of eggs and meat were developed during this period. Leghorns arrived in the United States between 1828 and 1831 and many importations followed. They were imported to England at a later date but had become popular by 1876. They represented the indigenous stock of Tuscany and took their name from the port city of Leghorn (Livorno). Coloring was not uniform at first, but fanciers soon had isolated a large number of varieties. Only the Single Comb White Leghorn remains in commercial use as the exclusive layer of white-shelled eggs. Brown - shelled eggs currently are derived from crosses involving several minor breeds, all of which were developed after 1850 as a dual purpose (eggs and meat) stock. Barred Plymouth Rock, Rhode Island Red and New Hampshire were all developed in the United States.

Present-day broilers are based heavily on a cross of Cornish with White Plymouth Rock. The Cornish was developed in England from Asiatic fighting stock; the white variety is unrelated to the original Dark Cornish, White Plymouth Rocks were derived as sports of the original breed in the United States,

Text 18. A ROMANOV RAM

Romanov is a breed of domestic sheep originating from the Upper Volga region in Russia. These domestic sheep got the name Romanov from the town of the same name. These sheep first got noticed in the 18th century. Soon after that they were imported into Germany and then into France. In the year of 1980, 14 ewes and 4 rams were brought by the Canadian government and were quarantined for 5 years. After the testing, some of the Romanov breeds were brought into the United States. So, nowadays the distribution of this unique breed is worldwide. This breed is raised primarily for meat.

These sheep are adapted to the cold inland climate and local feeding. Romanovs are one of the Northern European short-tailed sheep breeds. They are pure black when they are born, but as they grow older the color quickly changes to gray. The average weight of a male Romanov is 55-80 kilograms and the average weight of a female is 40-50 kilograms.

By 3-4 months old, Romanovs are sexually mature and will start breeding any month of the year. The ewe can produce quads, quintuplets, and even sometimes sextuplets. Romanov ewes tend to lamb in litters, unlike other sheep who give single or twin births. British and North American breeds of domesticated sheep are genetically different because the Romanov breed is a 'pure gene', not a 'cross'. But, they are often crossed with more popular breeds.

Romanov wool is very strong. The wool is double coated with mean diameter of wool fibers of 20.9 micrometers and 71.9 micrometers of outer-coat hair (lamb wool). Mean greasy fleece weight is around 4.5 kilograms. The wool, which is a mixture of gray wool and black guard hair, is usually used for rugs, mats, and wall hangings.