Doctoral Dissertation of Veterinary Professions
Abstract:
One ??of the best management tools is giving a body score, which is considered for producers as a factor for production, evaluation of health and nutritional status. This method helps to evaluate a group or herd of cows in terms of body reserves, especially fat and muscle. Body score may change at all stages of the production, feeding and management cycle. The physical score of each cow shows the ability to produce milk, reproduce and the economic life span of the cow in the herd. Diagnosis and body score is an indicator to check the amount of energy stored in the body and its changes can be seen in different stages of breastfeeding. Normally, newborn cows that are at the peak of milk production experience weight loss due to negative energy balance. This is while the cows that are at the end of the lactation period and the dry cows are in a positive energy balance and their weight increases. A suitable body score is necessary to maintain health and improve milk production and reproduction. The milk production of thin cows with low body score is reduced too much. Very fat cows also suffer from hard parturition, fatty liver, reproductive problems and metabolic disorders. In this study, an attempt was made to evaluate the effects of body score on the amount of milk production, some reproductive factors and the occurrence of some reproductive diseases in industrial cattle breeding in Chaharmahal and Bakhtiari province. All the cows under investigation were given a five-point scoring method in the three stages of pre-drying, after calving and first insemination, and the studied indicators were analyzed. Based on the experiments, we found out that the body score during dry season is based on the number of effective inseminations, the condition of the uterus, and corrected milk. It can be effective.
Key words: body score, dairy cow, milk production
Introduction
Dairy cow since long ago. It has played an important role in providing some nutrients needed by humans. The high nutritional value of milk for humans has been known and praised for centuries. Today, most of the milk produced in the world comes from cows. The increase in milk production of each cow is the result of breeding, more correct feeding and optimal management.
Having a good body condition score during drying, delivery and different stages of lactation will lead to an increase in milk production. Body condition score is a mental and visual method to evaluate the amount of energy stored in the form of fat in the body of a live animal (regardless of body size and weight). When cows have high milk production, they must consume more feed in early lactation to meet their total energy needs, but due to the decrease in dry matter consumption in early lactation, it is not possible to meet this high need from consumed feed, and it has been stated that the energy needs of dairy cows during early lactation can be met by feed consumption and transfer of body reserves [85]. These reserves include fat and protein, which by their decomposition, the fat and protein needed for milk synthesis are available to livestock. Especially fat tissue plays an important role in regulating the energy requirements of animals. In dairy cows, before parturition, adipose tissue adapts to increase the rate of lipid breakdown [64]. And after delivery, the breakdown of lipids in adipose tissue increases significantly [67,64]. A regular program of body condition scoring can help detect potential health problems before they can significantly reduce milk production. A large decrease in body condition score after calving may be related to the occurrence of metabolic diseases[41].
Increasing the genetic ability of cows to produce milk as a result of improved nutrition and management, despite the increase in milk production, has led to a decrease in reproductive performance. The decrease in reproductive performance of dairy cows has become a serious issue in the dairy industry for more than a few decades [82, 76, 13]. A number of studies have shown that there is a relationship between body condition score at birth and early lactation with reproductive performance [63,58,54,42,41].The objectives of this project include investigating the effect of the body condition score at the time of calving on the interval from calving to the first insemination, the rate of conception from the first inoculation, open days, the number of inoculations resulting in each pregnancy and the pregnancy ratio, evaluating the effect of the body score on the occurrence of some reproductive diseases in dairy cows, evaluating the effect of the body score on the amount of milk production in the mentioned groups at the time of calving.
The second chapter
General
2-1- Body condition score
Today, due to genetic progress and the progress achieved in the management of the dairy cattle industry, cows High production milk has been created, which requires better management in the field of dairy cows [61]. One of the best management tools is to give a body score, which is considered as a factor for production, health and nutritional status evaluation for producers. This method helps to evaluate a group or herd of cattle in terms of body reserves, especially fat and muscle. Body score may change at all stages of the production, feeding and management cycle. The body score of each cow indicates the ability to produce milk, reproduction, and the economic life span of the cow in the herd.
2-1-1 - History of body condition score evaluation
First Jefferies described the body condition score system for ewes in 1961 [51]. This system included touching the spine (Backbone process) and Lumbar process (Lumbar process), where the sharpness and covering of the bones are touched. Mice were graded on a scale of 0 to 5, where 0 was death and 5 was very fat. This technique was used by Lowman et al. in 1976 to score the body condition of beef cattle, which also used a scale of zero to five [59]. In this system, the spine and back were also touched. In addition, touching the end region of the tail (Tail head region) was also included. Following Mulvany in 1981, a system for use in dairy cattle was described, which was similar to beef cattle scoring with a series of minor changes in scoring in the loin area and end of the tail [73]. In 1982, Wildman first developed a system for scoring the body condition of dairy cows, in which scoring was done on a scale of one to five [99]. It included palpating the spine, back, and end of the tail to assess the amount of subcutaneous fat; Therefore, it was necessary to restrain the animals when scoring the body condition. Unfortunately, this type of evaluation was difficult in many production systems, especially in large herds. Therefore, Edmonson in 1989 developed a method to evaluate body condition based on the same one-to-five rating that observers could use under farm conditions [25]. In this method, which is still used today, eight stages are considered in three main areas, including the waist (Pin), pelvis (Pelvis) and the end of the tail, and people who have experience can visually evaluate the physical condition of dairy cows. style="direction: rtl;">The score of body condition is based on a five-point grading, where scores of one are considered for very thin animals and five for very fat animals. The body condition score is measured independently of the body and body size, and therefore it is a relatively accurate estimate of body fat [99]. Body condition score is directly related to body weight and body fat [99,97,52]. For each point of increase in body condition score, 56 kg is added to the weight of dairy cows on average [77].