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Effect of Parity on Udder Morphometry and its Association with Milk Yield of Jersey Crossbred Cows

Milk production of India increases consistently from 176.3 million tonnes in 2017-18 to 187.7 million tonnes in 2018-19 and registering a growth of 6.5 per cent (BAHFS, 2019). However, the crossbred cattle population of India is less and the total milk produced from the crossbred cattle is more compared to indigenous cattle. Indigenous buffaloes contributed nearly 35% of total milk production followed by crossbred cattle (26%), non-descript buffaloes (14%) and Indigenous cows (11%). In India, as per 2019 livestock census 50.42 million (26.19%) exotic/crossbred cattle recorded in a total of 192.49 million cattle population. Similarly, exotic and crossbred cows contribute significant role (6.48 million tonnes) in total milk production of Tamil Nadu (7.1 million tonnes).


Introduction
Milk production of India increases consistently from 176.3 million tonnes in 2017-18 to 187.7 million tonnes in 2018-19 and registering a growth of 6.5 per cent (BAHFS, 2019). However, the crossbred cattle population of India is less and the total milk produced from the crossbred cattle is more compared to indigenous cattle. Indigenous buffaloes contributed nearly 35% of total milk production followed by crossbred cattle (26%), non-descript buffaloes (14%) and Indigenous cows (11%). In India, as per 2019 livestock census 50.42 million (26.19%) exotic/crossbred cattle recorded in a total of 192.49 million cattle population. Similarly, exotic and crossbred cows contribute significant role (6.48 million tonnes) in total milk production of Tamil Nadu (7.1 million tonnes).
Physical characters of udder and teat have a direct correlation on milk yield of dairy cows and buffaloes. Variations in udder and teat characters are observed between breeds and individuals in the same herd with respect to parity and lactation stages. Udder is the first site of judgment for judging the milk production potential of dairy animals in our country (Khatri et al., 2017).
Dairy farmers are unaware of knowledge on udder morphometry and its relationship with milk production. They are not maintaining proper production records of their animals in an organised manner.
While selecting the high yielding dairy cows, it is necessary to know the udder and teat measurements and its association with total milk yield. Hence, this study was conducted in Jersey crossbred cows to investigate effect of parity on udder and teat measurements and its relationship with total lactation yield.

Materials and Methods
The study was conducted in dairy herds of Tirunelveli, Thoothukudi and Tenkasi districts of Tamil Nadu. The udder and teat measurements were recorded for 75 lactating Jersey crossbred cows with different parities. All the parameters have been recorded from beginning of the study and milk yield was recorded for the complete lactation period of cows.
Udder length (UL) was measured as a distance from the rear attachment of udder below the vagina and moving along udder body up to the fore attachment, where fore udder blends smoothly with the body of the animal. Udder width (UW) was measured as a distance between widest point of udder near the stifle joint of animal and passing it in between the fore and rear teats, to the widest point of udder near the stifle joint of the other side by using measuring tape. Udder depth (UD) was measured as the distance between the roof of the udder to the floor of the udder.
Teat length (TL) was measured from the base of teat up to its tip. Considering the uneven size of teats from the same animal, the length of all four teats i.e. All four teat length were recorded using the measuring scale and teat diameters were measured with the help of Vernier caliper. The milk yield of Jersey crossbred cows were measured throughout the lactation.
An analysis of variance was employed to compare udder and teat measurements with total milk yield between different parity groups of Jersey crossbred cows. The correlation between the udder and teat measurements and total milk yield was performed using a Pearson's correlation coefficient test. The statistical analysis was made using SPSS 16.0 (IBM Corporation, Armonk, New York, USA).

Results and Discussion
The mean±SE values of udder length, width and depth (cm)  Perusal of data shows that the gradual increase in udder measurement as the parity increases and had declining trend from 4 th parity onwards in Jersey and Red Sindhi crossbred cows (Ghosh and Prasad, 1998) and Murrah buffaloes (Prasad et al., 2010). Lavania et al., (2011) andKhrati et al., (2017) observed the gradual increase in udder measurements upto 4 th parity and declining trend from 5 th parity onwards in Surti buffaloes.   The mean±SE values of fore and rear teat lengths were 4.68±0.69 to 5.57±0.25 cm and 4.34±0.006 to 5.00±0.23 cm, respectively. The fore teat and rear teat length between different parities ranged from 4.68±0.69 to 5.57±0.25 and 4.34±0.06 to 5.00±0.23 cm, respectively and differed significantly (P<0.01) ( Table 2). Kuczaj Marina (2003) observed that as the advancement in parity of Holstein crossbred cows the fore teat length has also increased. Extremely significant effect of parity on teat length has been observed in Vrindavani cattle and Gir cows (Singh et al., 2010 andSinghai et al., 2013).
The mean±SE values of front teat diameter and rear teat diameter ranged from 2.78±0.17 to 2.66±0.29 and 2.68±0.18 to 2.78±0.06, respectively. The teat diameter between different parities was not differed significantly (Table 2). Similar results were observed by Modh et al., (2017) in Gir cows.
Correlation coefficients between the total milk yield and udder depth (0.442) were found highly significant (P<0.01) ( Table 3). Mingoas et al., (2017) reported that the depth and height of udder had highly significant (p<0.001) effects on milk yield. Udder length, width and depth were positively correlated with milk yield of buffaloes (Khrati et al., 2017;Prasad et al., 2010) and crossbred cows (Patel et al., 2016). The test day milk yield was correlated with udder and teat measurements of Gir cows, Vrindavani cattle and Crossbred cows (Modh et al., 2017, Singh et al., 2031and Deng et al., 2012. The udder length was correlated with udder width (0.348) and depth (0.315), udder width was correlated with udder length (0.348) and depth (0.307) and the udder depth was correlated with udder length (0.315) and width (0.307), respectively (Table 3). The results of the udder measurements were closely interrelated and reflect that all three udder morphometric characters (length, depth and width) must be the vital criteria for selection of dairy cows.
The total milk yield of Jersey crossbred cows were not correlated with teat measurements. The result was similar to the report of Gupta et al., (1991) in Karan Fries cows and Patel et al., (2016) in crossbred cows and Mingoas et al., (2017) in Zebu cows of North region of Cameroon, they reported that correlation coefficient of teat length and teat diameter with total milk yield were not significant.
providing facilities to carry out the research work.
In conclusion the correlation coefficients between milk yield and udder measurements are useful in the selection of dairy cows. While considering the parity of dairy cows the gradual increase of udder and teat measurements have been observed upto fifth parity. Beyond five calving it may not have significant effect on udder morphometry. By applying this method of correlation will be useful for genetic improvement of dairy cows in organized farms and farmers field.