Effect of Linear Type Traits Influences on Survivability and Longevity of Sahiwal Cattle

The conformation or linear type trait of animal is one of the essential factors for the breeding and selection of dairy cattle. The longevity of animal largely depends on linear type traits especially the traits which are related to udder, feets and legs (Bunger et al., 2001; Ducrocq, 2001). These traits are important criteria during selection of animals as it is not only the better indicator of health condition Saloniemi et al. (1986) but also a reflection of its production performance and temperament (Blake and Mc Daniel, 1979). However, these traits vary with time period or physiological stage of animals. The milk yield can be tremendously affected by the poor udder conformation leading to udder deformities and sometimes such animals are even prone to mastitis resulting in huge economic loss. The shapes, location, strength and attachment of udder are heritable traits having ability to alter the morphological structure of cow’s udder (Atkins, 2007). Dairy animal basically has open and well sprung fore and rear ribs with wide chest and sufficient body depth to support the ability to produce milk performance and temperament (Blake and Mc Daniel, 1979). However, these traits vary with time period or physiological stage of animals. The milk yield can be tremendously affected by the poor udder conformation leading to udder deformities and sometimes such animals are even prone to mastitis resulting in huge economic loss. The shapes, location, strength and attachment of udder are heritable traits having ability to alter the morphological structure of cow’s udder (Atkins, 2007).  Dairy animal basically has open and well sprung fore and rear ribs with wide chest and sufficient body depth to support the ability to produce milk. Animals with narrow chest width, having high risk of culling it necessary to measure the chest width. The rump angle with straight to moderate slope from hip to pin bone have been linked with less reproductive  problems and less involuntary culling (Caraviello et al., 2004; Sewalem et al., 2004). Thus, it may be the reason that the incidences of reproductive problems were less in Sahiwal herd. In narrow rump width animals are more prone to calving problems (Cue et al., 1990). Intermediate type of rear leg set is expected to possess the longer herd life (Atkins and Shannon, 2002). Udder depth is positively correlated with length of productive life of animal (Larroque and Ducrocq, 2001).

Time and place of experiment
 
Total 86 Sahiwal cows were selected for this experiment. The experiment was conducted in February to June month of 2019 at the Bull Mother Experimental Farm and Government Cattle Breeding Farm located at the campus of College of Veterinary Science and Animal Husbandry, Dau Shri Vasudev Chandrakar Kamdhenu Vishwavidyalaya, Anjora, Durg (C.G.).
 
Measurement of linear type traits
 
The linear type traits in Sahiwal cattle were measured as per the recommendation of ICAR (2018).
 
Stature: The stature, indicating height of animal at highest point of spine was noted in Sahiwal cows.
 
Chest Width: This trait is measured from rear as a distance between top of two fore limbs.
 
Rump angle: This trait indicated the angle between highest point of hook bone to the highest point of pine bone.
 
Rump width: It is the distance between two pin bones of cows.
 
Rear leg set (Side view): Rear leg set, as viewed from side, measures angle of hock joint.
 
Rear leg set (Rear view): The distance between hock joint and between two fetlock was measured and difference between both the distance is termed as rear leg set (rear view).
 
Udder depth: The depth of udder was measured as a difference in distance between the floor of udder to the hock joint.
 
Rear udder height: The rear udder height indicated the vertical distance from bottom of vulva to milk secreting tissue.
 
Udder cleft: The udder cleft was measured at base of the udder supported by central ligament.
 
Fore udder attachment: This trait was measured as an angle between fore part of udder and abdominal wall.
 
Front teat position: The front teat placement was measured from the centre of quarter of cows.
 
Stastical analysis
 
The mean, standard error and coefficient of variation of data were calculated by using formula given by Snedecor and Cochran (1989).

Stature
 
The stature, indicating height of animal at highest point of spine was noted in Sahiwal cows and the mean value of stature was found to be 125.39±0.534 cm (Table 1) with maximum value 137.60 cm was recorded (Table 2). The maximum number tall types of Sahiwal cows were found to be 54.64%, it might be the one of the reason for less culling rate.




 
Chest width
 
The average value of chest width was 27.74±0.49 cm with coefficient of variation of 17 per cent (Table 1). The minimum and maximum values of chest width were 18.40 and 39.30 cm respectively (Table 2). Moreover, the values of this trait in percentage for narrow, intermediate and wide groups were 31.35 per cent, 52.35 per cent and 16.30 per cent respectively (Table 3). According to Atkins (2007), the animals with wide chest width is desirable as it support the ability to produce high quantity of milk. However, the cows with wide chest width, reduces the risk of culling. Since, in present study, the maximum percentage of animals comes under intermediate type of chest width (52.35%) which could be one of the reasons for low culling rate in Sahiwal cows.


 
Rump related traits
 
Rump angle and rump width were traits related to rump. The mean values of rump angle and rump width were 12.75±0.97 cm and 17.32±0.29 cm respectively (Table 1). The maximum frequencies of rump angle and rump width were observed intermediate type i.e. 58 (67.50%) and intermediate type 49 (57.00%) respectively in Sahiwal cows (Table 3). According to ICAR (2010), the animal had been low rump angle and extreme slope with narrow rump width (Cue et al., 1990) which is considered as unacceptable, while, animal with intermediate rump angle is considered as acceptable. Cow’s with straight to moderate rump angle and intermediate rump width has been linked less reproductive as well as less calving problems (www.wales.co.uk) and reduces the risk of involuntary culling (Caraviello et al., 2004; Sewalem et al., 2004). Since, in present investigation, maximum number of cows comes under intermediate group. It could be one of the reasons for fewer incidences of calving difficulties and other reproductive problems as observed in Sahiwal herd.
 
Rear leg related traits
 
The rear leg set (side view) and rear leg set (rear view) such traits related to rear legs. in present experiment, the mean values of rear leg  set (side view) and rear leg set  (rear view) were 146.03±0.91 degree and -3.74±0.15 (Table 1). The maximum values of rear leg set (side view) and rear leg set (rear view) were 164° and1.30 cm respectively (Table 2). In present study, the maximum frequency of cattle was intermediate types of (65.20 per cent) and rear leg set (rear view) (51.60 per cent) (Table 3). Accordance to McDaniel (1994) cattle with both the extremities i.e. straight and sickle leg are linked with reduced longevity. Cows with intermediate type of rear leg set (side view) could be associated with increased longevity (Atkins and Shannon, 2002) and increased production and profitability (Perez-Cabal and Alenda, 2002). According to Atkins (2007) the 41 per cent of total variation of locomotion/ movement was influenced by leg traits, out of which approximately 55 per cent was contributed by rear leg set (rear view). Moreover, the incidence of toes out and bowlegged condition reduces the longevity as well as production performance of a herd. In present study, most of the animals possess the intermediate type of both traits such as of rear leg set (side view) and (rear leg set rear view), hence, it could be assumed that relative risk of involuntary culling due to lameness might be less in Sahiwal cattle, it might be assumed that Sahiwal cattle possess more longevity.
 
Udder related traits
 
Udder depth, udder cleft, rear udder height, fore udder attachment and front teat placement were traits related to udder. The average value of udder depth, udder cleft, rear udder height, fore udder attachment and front teat placement were found 18.97±0.43 cm, 2.77±0.95 cm, 24.06±0.45 cm, 130.50°±1.75° and 3.61±0.13 cm respectively (Table 1) The maximum value of all this traits were found to be 28.00cm, 4.70 cm, 33.70cm 159° and 5.70 cm respectively (Table 2).  Under 1 -9 point scoring system the percentages of all traits (except fore udder attachment) were recorded as intermediate type in Sahiwal cattle. The frequencies were 65.20%, 51.16%, 64.0% and 53.49% for udder depth, udder cleft, rear udder height and front teat placement respectively (Table 3). But, in present study, the percentage of fore udder attachment was strong udder attachment in Sahiwal cows. According to Carlen et al., 2004, cows with deep/ below hock udder increased risk of mastitis and locomotion problems.
       
As per the guidelines of ICAR (2018), cattle with strong central ligament are better than weak ones since; the udder is attached on the pelvic cavity by means of the medial and lateral suspensory ligaments of udder cleft. Thus, the animals with strong udder cleft can bear more weight of udder when filled with milk. However in case of weak / loose ligament, the risk of udder damage is high. Udder cleft is the one of most important traits which is associated with udder health. Hence, the udder cleft has greater influence on the longevity and productive performance of animals (Vollema et al., 2000; Larroque and Ducrocq, 2001 and Schneider et al., 2003). The animals with strong fore udder attachment is supposed to provide ample surface for secretory tissue of udder to synthesize more milk. According to ICAR (2010), in dairy cattle, very low and intermediate type of the rear udder height is considered as undesirable, while high rear udder height is considered as desirable. It may be due to the fact that animal with high rear udder height provides greater surface area for secretary tissues of udder to synthesize larger amount of milk.
       
In present study, the highest frequency was observed for intermediate type of all udder related traits in Sahiwal cows, which might be one of the reasons for low incidences of mastitis and improves the milk productions.

It is concluded that the linear type traits such as chest width, rump width, rump angle, udder depth, rear leg set (side view), rear leg set (rear view) and udder cleft were intermediate types observed. Hence, it could be reason that low culling rate in Sahiwal herd and increase the longevity and fewer reproductive problems.