Determining Characteristics of Udder and its Relationship to Quantity and Quality of Milk and Factors Affecting Parameters of Lactation Curve on Shami Cows

The study was carried out at Deir Al-Hajar Research Station for Improving Shami cows, affiliated to the Livestock Research Department, General Commission for Scientific Agricultural Research. 1420 records from 71 Shami cows were analyzed during the period 2018–2020. The study aimed to determine thThe results indicated that there was a significant effect (P<0.01) of the cow season arrangement in the characteristics of measurements of length, width, depth, circumference, and udder size, where the multi-season cows recorded higher values than the first. Season's first cows scored higher than multi-season cows in the udder height scale trait. the nature of the udder had a significant effect (P<0.01) on the characteristics of the udder. Length, width, circumference, and udder size of cows, daily and total milk production, and length of the lactation seasone specifications of the udder and the teat and their relationship to milk, to estimate the phenotypic relationships between the dimensions of the udder and the teat, to characterize the milk curve using the incomplete linear gamma function and the factors affecting it, and to estimate the milk curve coefficients for Shami cows.The statistical analysis program SAS (1996) was used and the data were subjected to general linear modeling and analysis of variance was used to determine the effect of different factors and Pearson's correlation to determine the amount of association between the studied traits, and Duncan's test was applied to compare the averagesThe nature of the udder had a significant effect (P<0.01) on the characteristics of measurements of length, width, circumference and udder volume of cows, daily and total milk production, and length of the lactation season, as cows with spongy udder nature were distinguished over cows with a muscular udder nature.Four udder shapes were found in Shami cows (cup, spherical, suspended and floor), and they had a significant effect (P<0.01) in the characteristics of measurements of width, depth, circumference and volume of the udder. The ground from the rest of the other forms of udder, which is a bad quality for cows.The cup shape was characterized by daily and total milk production and lactation season length compared to other udder shapes, and the cow season arrangement had a significant effect (P<0.01) in the measure of nipple length, where the cows of the first season recorded the highest values compared to the cows of other seasons.In the dimension of measuring the diameter of the nipples, the cows of the fifth season recorded the highest values compared to the cows of the other seasons. In the dimension of measuring the distance between the nipples, the cows of the fourth season recorded the highest values compared to other seasons, and it was noted that the distance between the nipples increased with the progression of the cow parity.The cows of the first season were distinguished in measuring the height of the nipples from the ground compared to the cows of the fifth season. The shape of the nipples of Shami cows was classified into three shapes (cylindrical, conical, and pear-shaped), and it had a significant effect (P<0.01) on the characteristics of the measurements of the length and diameter of the nipples and the distance between them. Where the pear shape recorded the highest values and the highest production of daily and total milk and for the length of the lactation season was found in the conical nipple. The results showed that there was a significant effect (P<0.05) of the cow's season arrangement on the length and diameter of the nipple duct, and the duct length and diameter of the anterior nipples were greater than that of the posterior nipples. An increase in the length and diameter of the nipple duct was observed with the advancing age.It was found that cows with greater nipple duct length and diameter showed the lowest milk production. The results showed that there was a significant effect for the age of the cow at birth on peak production (PY) and the time to reach peak production (PT). A significant effect was found for the order of the cow season on the number of somatic cells, the number of somatic cells increased with the progression of the production season, and the number of somatic cells was in the posterior quadrants. It was higher than the front quartiles and was 209.8±5.8×103 cells/ml.The results of the study showed a significant effect of the nature of the udder on the number of somatic cells. Where the spongy udder is superior to the muscular udder.