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0UDC 619:617.3:575.22:636.2
INFLUENCE OF GENETIC FACTORS ON THE FORMATION OF FIRST-CALF HEIFERS EXTERIOR AND RELATIONSHIP OF OVERALL COMPREHENSIVE ASSESSMENT WITH MILK PRODUCTIVITY
VDOVYCHENKO YURIY VASYLOVYCH
Doctor of Agricultural Sciences, Senior Researcher, Corresponding Member of NAAS
CHERNIAK NAZARII SERHIYOVYCH
PhD Student
Institute of Animal Breeding and Genetics named after M.V. Zubets of NAAS 08321, Pohrebniaka St., 1, Chubyns'ke village, Boryspil district, Kyiv region, Ukraine
Abstract. Linear evaluation of first-calf cows by exterior type was conducted under the conditions of the dairy complex of LLC "Ostriikivske". The degree of development of the main descriptive exterior traits ofHolstein first-calf cows indicates their significant intra-herd variability. Differences were established in the absolute values of individual measurements of Holstein first-calf heifers of different paternal origin. The influence of the father on the variability (12.95-37.69%) of descriptive traits of linear classification by type was revealed.
The research results show that the highest score for the complex of traits (84.08 points) and better milk productivity is observed in daughters of the bull Elkhart 3148929453 of the Elevation 1491007.65 Holstein line, whose milk yield is 11,540 kg, fat content 4.22% and protein content 3.20%.
The application of linear classification methodology in the breeding process of dairy cattle is a quite effective means of objectively determining the breed characteristics of cows by exterior, and the existence of a relationship between group linear traits and milk yield is a guarantee of the effectiveness of animal selection by type.
Key words: linear type assessment, exterior traits, milk productivity^first-calf heifers, holstein
breed.
In practical dairy cattle breeding, special attention is paid to the assessment and selection of animals by external forms and body structure proportions. This is due to the relationship established by many studies between the exterior-constitutional characteristics of cattle and their economically useful traits (Khmelnychy et al. 2019).
Since the exterior type is the most important component of the constitution and is its external expression, this feature in breeding practice is considered in all the complexity of its relationship with the productive qualities of animals. Over many years of improving dairy cattle, information has been accumulated about the magnitude and direction of relationships between a number of exterior indicators and the main economically useful traits (Pendyuk et al, 2020; Karateeva & Lesik, 2020).
According to the authors Polupan et al, (2021), the broad possibilities of the linear classification methodology are revealed through its accessibility, simplicity, the ability to assess traits that are difficult or impossible to measure, to draw the exterior profile of daughters evaluated by the offspring of breeding bulls and move from phenotype evaluation to genotype evaluation.
The authors L. M. Khmelnychy & V. M. Karpenko (2021) in their work indicate that visual assessment of the exterior by the method of linear classification by body type is a necessary element of comprehensive analysis of dairy cattle.
With intensive use of dairy cows, quality products can be obtained only under conditions of successful breeding of cows for suitability for breeding in industrial technology conditions (O. O. Borsch & O. V. Borsch, 2021).
Assessment and selection of dairy cattle by exterior and constitution (Ladyka et al., 2023) are closely related to the general direction of breeding work to improve the herd. Animals with a strong constitution and, accordingly, exterior indicators of type, in conditions of industrial production can have high milk productivity, reproductive ability, endurance and ability for long life and lifetime productivity (Polupan et al, 2021). In their work, Y. P. Polupan and S. V. Pryima (2023) indicate that improvements in exterior and milk production are not only due to the combined effects of a complex of economic and natural conditions, enhanced technological conditions of housing and feeding, and better rearing of replacement heifers but also the simultaneous impact of genetic progress in the herd through the use of Holstein bulls.
Each specific herd has its own characteristics in forming and expressing key economically beneficial traits, which must be considered when planning breeding work, prioritizing animals that produce more with fewer costs. A successful combination of productive qualities with constitution strength and exterior type is desirable for dairy breeds. The use of Holsteins, which have high milk productivity and good exterior-constitutional traits, exemplifies this (Dankiv et al., 2020; Strapakova et al., 2021).
A certain connection has been established between the exterior-constitutional characteristics of animals and their live weight, growth, condition, productivity (Yelemesov, 2020; Baimukanov, 2022), health, resistance, and the duration of productive use (Fedorovych et al., 2019). In other words, there is an observable link between form and function, exterior and body proportions, and the functional reliability of their organism as a whole biological system (Pendyuk et al., 2020; Karateeva & Lesik, 2020).
Recently, several studies by V. I. Ladyka et al. (2019) and V. M. Karpenko (2021), both within Ukraine and abroad, have demonstrated the reliable impact of evaluating linear descriptive exterior traits on the lifespan of dairy cows of various breeds.
Given the importance of linear classification in the context of effective dairy cattle breeding based on exterior type, which primarily affects milk production, it is deemed necessary to continuously assess dairy cows based on linear traits. This underlines the relevance of these studies.
The objective of the study was to investigate the influence of genetic factors (paternal origin, lineage) on the formation of the exterior of first-calf Holsteins and to establish the connection between group exterior traits and milk productivity.
Materials and Methods. The research was conducted at the dairy complex of LLC "Ostriykivske" in Kyiv Oblast. Data from the electronic information database in the SUMS ORSEK format was used. The exterior of first-calf heifers was assessed visually using the linear classification methodology (Khmelnychy et al., 2016).
Linear exterior evaluations of cows were carried out between the 2nd and 4th months of lactation, but no earlier than 15 days post-calving. Cows were selected randomly. The evaluation of the cows' type was conducted using two systems: a 9-point scale for individual exterior traits and a 100-point scale for overall type traits. The average expression of a trait is assessed on a five-point scale, with biological deviations ranging from 1 to 9 points.
Key linear exterior traits assessed included height, chest width, body depth, angularity, slope and width of the rear, rear limbs (view from behind and side), hoof angle, gait, front udder attachment, positioning of front and rear teats, teat length, udder depth, rear udder height, central ligament, and condition.
The total score was calculated based on composite traits, which in turn are based on linear descriptive traits. The 100-point system considered four complexes of linear traits, characterized as: dairy type (15%), body (20%), limbs (25%), and udder (40%). Each exterior complex was evaluated separately with the corresponding weight coefficient in the final animal assessment. During the evaluation process, results were recorded in the dairy cattle evaluation log, noting the animal's identification number, name, birth date, calving date, and lactation number. A total of 210 first-calf Holsteins were assessed in the farm. The maximum score for first-calf cows was no more than 89 for each individual trait complex. According to the international grading scale, the evaluations were as
ОФ "Международный научно-исследовательский центр "Endless Light in Science"
follows: 85-89 points - very good (VG), 80-84 points - good plus (GP), 75-79 points - good (G), and 70-74 points - satisfactory (S). The reliability of the obtained data was assessed by calculating the standard errors (S.E.) and Student's t-test (td) for correlation analysis. The level of significance was determined by comparisons with standard criteria. Results were considered statistically significant at the following thresholds: first - P<0.05 (*), second - P<0.01 (**), and third - P<0.001 (***). Data analysis was performed using Microsoft Excel 2020.
Results of research. Linear evaluation of first-calf Holsteins based on body type was conducted at the LLC "Ostriykivske" farm (Table 1).
Table 1. Impact of Eleveishna 1491007.65 line bulls on linear type traits of their progeny
Traits, points Elkhart 3148929453 (n=35 гол) Bossa 1339112680 (n=35 гол) Progenesis 13227420 (n=35 гол)
height 6,29±0,05 6,20±0,06 5,63±0,06
chest width 5,83±0,06 5,13±0,07 5,67±0,05
body depth 6,34±0,04 6,08±0,05 6,60±0,06
angularity 5,46±0,06 5,06±0,04 4,86±0,07
rump angle 3,50±0,07 4,37±0,08 3,97±0,06
rump width 6,69±0,05 6,30±0,06 6,43±0,07
rear legs angle 5,09±0,06 5,03±0,05 5,10±0,08
rear legs rear view 6,71±0,04 7,23±0,05 6,11±0,06
foot angle 5,11±0,07 5,26±0,06 3,97±0,05
fore udder attachment 6,97±0,05 6,09±0,07 5,60±0,06
rear udder height 7,40±0,04 5,43±0,05 5,45±0,08
central ligament 6,64±0,10 5,37±0,09 5,11±0,07
udder depth 6,14±0,04 5,09±0,06 5,01±0,09
fore teat placement 5,11±0,05 5,00±0,07 5,14±0,04
rear teat placement 5,34±0,06 5,03±0,08 5,37±0,05
teat length 3,91±0,04 4,17±0,05 3,94±0,05
Source: Developed by the author.
Note: River 12843180 - bull's name, (n=35 daughters) - number of the bull's daughters.
The body structure of the assessed first-calf cows (n=210) has a sufficiently good description of the traits. Body depth depends on age and lactation period and adequately characterizes the development of the digestive tract. For this trait, there is a statistically significant advantage in favor of the daughters of the bull Progenesis 13227420, with a difference of 0.3-0.7 points (P<0.001).
In terms of chest width, which characterizes the animal's sturdiness, higher variability is observed, with better trait evaluation in the daughters of the bull River 12843180 of the Chief 142738 line, showing a significant difference of 0.17-0.85 points (P<0.001).
When evaluating the milk system, traits that determine high milk yield, suitability for machine milking, and prevention of injury are prioritized. The central ligament is well-developed in the
daughters of the bulls Elkghart 148929453 and River 12843180 (6.74-6.64 points), which ensures a strong udder attachment throughout lactation (Table 2).
The height of the rear udder is an indicator of a cow's potential milk production capacity. This trait is highest in the daughters of the bull Elkghart 148929453, scoring 7.40 points (P<0.001). The front part of the udder is firmly attached to the abdominal wall, sufficiently long, and with evenly developed quarters in the daughters of this bull (6.97 points) (P<0.001).
Table 2. Impact of Chief ' 142738 line bulls on linear type traits of f heir progeny
Traits, points River 12843180 (n =35 гол) Metropolis 12857836 (n =35 гол) Saluki 12638320 (n =35 гол)
height 6,60±0,05 6,3 ± 0,06 6,4 ± 0,06
chest width 5,97±0,06 5,9 ± 0,07 5,7 ± 0,05
body depth 6,57±0,04 5,9 ± 0,05 6,9 ± 0,06
angularity 5,37±0,06 4,4 ± 0,04 3,7 ± 0,07
rump angle 4,43±0,07 3,8 ± 0,08 4,5 ± 0,06
rump width 6,51±0,05 6,8 ± 0,06 7,3 ± 0,07
rear legs angle 5,32±0,06 4,7 ± 0,05 5,3 ± 0,08
rear legs rear view 6,97±0,04 7,1± 0,05 6,3 ± 0,06
foot angle 4,94±0,07 4,4 ± 0,06 3,4 ± 0,05
fore udder attachment 6,95±0,05 5,3 ± 0,07 4,3 ± 0,06
rear udder height 6,84±0,04 6,2 ± 0,05 5,3 ± 0,08
central ligament 6,64±0,10 5,2 ± 0,09 4,6 ± 0,07
udder depth 6,14±0,04 5,5 ± 0,06 4,8 ± 0,09
fore teat placement 5,11±0,05 4,9 ± 0,07 4,8 ± 0,04
rear teat placement 5,34±0,06 5,4 ± 0,08 5,2 ± 0,05
teat length 3,91±0,04 3,8 ± 0,05 4,2 ± 0,05
Source: Developed by the author.
Udder depth depends on the age and milk production of cows. This trait is lowest in the daughters of the bull Saluki 12638320 from the Chief 142738 line (4.8 points). This means that with each lactation, the udder will drop, making it more susceptible to infections and injuries.
In terms of angularity, the daughters of the bull Saluki 12638320 lag behind their peers with a significant difference (P<0.001). This trait is best in the daughters of the bull Elkghart 148929453, indicating their high milk productivity.
The rear udder slope significantly affects reproductive performance in cows. Very high hips pose a risk of infection in the birth canal. In evaluating this trait, the assessed animals showed an average rear slope.
All assessed animals had a generally wide rear (6.7 points), with the widest measure in the daughters of the bull Saluki 12638320 (7.3 points) and an advantage over the other daughters of evaluated bulls by 1.0-0.5 points (P<0.001). This trait affects reproduction; the wider the hips, the wider the rear part of the udder and birth canal, making calving easier.
When evaluating the condition of the pelvic and thoracic limbs and hooves, the animals ability to move freely and withstand loads is considered. Strong, correctly placed limbs are an important indicator when describing the exterior of cows. From the side view, the hock joints in the assessed cows are well-developed, clearly defined, without pathological swellings or tumors. The pelvic limbs viewed from behind are straight, with a wide and parallel stance, and from the side view - straight. The hooves are strong, well-rounded, with an optimal hoof angle.
According to the research by Y. P. Polupan & S. V. Pryima (2023), paternal origin accounted for 8.8-45.9% of the variation in the measurements of first-calf heifers and 10.5-40.5% of the variation in linear descriptive traits. The high variability of descriptive linear traits found by A. V.
Loboda et al. (2019), ranging from 12.6-36.3%, indicates the current lack of adequate selection for these traits and the potential for effective selection based on them.
Thus, differences have been established in the main descriptive exterior traits of first-calf Holsteins from different paternal origins. According to the linear evaluation of the test herd, the highest overall rating was observed in the daughters of the bull Elkghart 3148929453 (84.08 points), who outperformed their peers by 0.69-3.97 points (P<0.001) (Table 3).
Table 3. Overall evaluation of the daughters of Holstein bulls, in points (x ± S.E)
Com] plex traits, points, %
Name bull milk type body limbs udder overall evaluation
Elkhart 84,28±0,40 84,23±0,73 80,77±0,53 85,64±0,44 84,08±0,36***
3148929453 Cv=2,8 Cv=5,19 Cv=3,86 Cv=3,02 Cv=2,53
Bossa 83,5±0,29 83,6±0,64 79,0±0,54 83,2±0,54 82,50±0,26
1339112680 Cv=2,04 Cv=3,79 Cv=4,01 Cv=3,86 Cv=1,87
Progenesis 80,8±0,64 81,5±0,67 78,7±0,51 81,8±0,64 80,39±0,47
13227420 Cv=4,68 Cv=4,89 Cv=3,83 Cv=4,60 Cv=3,47
River 82,91±0,75 84,91±0,61 78,37±0,50 85,11±0,61 83,39±0,35***
12843180 Cv=5,41 Cv=4,37 Cv=3,85 Cv=4,37 Cv=3,38
Metropolis 79,57±0,75 82,80±0,61 77,06±0,50 82,09±0,58 80,89±0,37
12857836 Cv=4,41 Cv=4,37 Cv=3,85 Cv=4,37 Cv=3,38
Saluki 80,46±0,70 82,0±0,86 77,2±0,65 79,03±0,66 80,11± 0,39
12638320 Cv=4,92 Cv=4,92 Cv=4,92 Cv=4,92 Cv=2,86
In terms of dairy type, the daughters of the bull Elkghart 3148929453 show a significant advantage over their peers by 3.82 points (P<0.001), with a difference of 3.71 points in the evaluation of leg and hoof condition (P<0.001). We also note better udder development in the cows of this bull, which exceeded their peers by 6.61 points (P<0.001).
At the same time, undesirable development of certain exterior traits is observed in the evaluated cows (Fig. 1). Extra teats were found in 6,8% of the evaluated animals.
■ extra teats ■ rudiments
■ atrophy of the udder lobes ■ underdevelopment of the udder lobes
■ stepped udder ■ closeness of the rear teats
Fig. 1. Undesirable development of certain traits, %
The presence of extra teats is usually considered a disadvantage when evaluating the exterior of cows and leads to a decrease in the cow's breeding value. Moreover, extra teats contribute to mastitis of the udder, affecting the quality of milk and the health of the animal. Additionally, extra teats affect the cow's appearance and its efficiency in milk production. The trait of having multiple teats is consistently transmitted through both the maternal and paternal lines.
In the evaluated cows, 6.8% showed close rear teats. This characteristic is a disadvantage when milking on robotic and automated dairy farms. Besides, the evaluated cows exhibit undesirable development of certain exterior traits, including rudiments placed behind the teats, underdeveloped udder lobes, and diseased limbs.
The results of the linear classification of first-calf heifers on a 100-point scale indicate that within the group traits, the average evaluation level is in the "good with a plus" category (Table 4).
Table 4. Influence of the Overall Complex Evaluation on the Milk Productivity of First-Calf
Heifers of the Holstein Breed (x ± S.E)
Number of Complex Milk yield, kg Fat, Protein,
Name bull daughters, goals score, points % %
Elkhart 35 84,08±0,36*** 11540±320*** 4,22±0,04*** 3,20±0,01
3148929453 Cv=2,53 Cv=21,20 Cv=5,7 Cv=3,0
Bossa 35 82,50±0,26 10480±204,7 4,10±0,07 3,19±0,01
1339112680 Cv=1,87 Cv=19,6 Cv=6,21 Cv=1,82
Progenesis 35 80,39±0,47 9380±221,6 4,05± 0,03 3,12±0,01
13227420 Cv=3,47 Cv=16,42 Cv=4,34 Cv=2,32
River 35 83,39±0,35 11320±200,4 4,20±0,05 3,22±0,01***
12843180 Cv=3,38 Cv=15,6 Cv=4,62 Cv=2,01
Metropolis 35 80,89±0,37 10420±198,4 3,85±0,07 3,12±0,01
12857836 Cv=3,38 Cv=14,6 Cv=4,16 Cv=2,12
Saluki 35 80,11± 0,39** 9254±188** 3,80±0,07 3,12±0,01
12638320 Cv=2,86 Cv=15,2 Cv=5,52 Cv=2,54
Source: Developed by the author. Note: P<0.001 (***).
The highest score for a complex of traits (84.08 points), corresponding to "good with a plus," and higher milk productivity is noted in the daughters of the bull Elkghart 3148929453 of the Elevation 1491007.65 line of the Holstein breed. Their yields were 11540 kg, milk fat - 487 kg, and milk protein - 369 kg. The daughters of the bull River 12843180 of the Chief 142738 line also received a high score for a complex of traits (83.39 points) and for milk productivity indicators (yield - 11320 kg; fat - 4.20%; protein - 3.22%). The descendants of the bull Saluki 12638320 of the Chief 142738 line of the Holstein breed showed the lowest score for a complex of traits (80.11 points) and lower milk productivity indicators (yield - 9254 kg; milk fat - 352 kg; milk protein - 289 kg) compared to the daughters of other bulls.
In terms of yield, the daughters of Elkghart 3148929453 outperformed the daughters of Saluki 12638320 by 2,286 kg (p<0.001), in terms of milk fat content by 0.42% (P<0.001), and in terms of milk protein content by 0.08% (P<0.001); the daughters of River 12843180 outperformed the daughters of Saluki 12638320 by 2,066 kg of milk (P<0.001), in terms of milk fat content by 0.42% (P<0.001), and in terms of milk protein content by 0.09% (P<0.001).
Thus, the selection for the repair of the dairy herd of first-calf heifers of the Holstein breed with better performance in a complex of traits will ensure more functional reliability and high milk productivity.
Conclusions.
The genetic factor (sire, line) has a significant impact on the variability of linear exterior traits of Holstein cows. Sire origin determined 12.95-37.69% of the variability of descriptive traits of linear classification by type. The highest score for a complex of traits and higher milk productivity is observed in the daughters of the bulls Elkghart 3148929453 of the Elevation 1491007.65 line (complex score - 84.08 points; yield - 11640 kg; fat - 4.22%; protein - 3.20%) and River 12843180 (83.39 points) of the Chief 142738 line (yield - 11320 kg; fat - 4.20%; protein - 3.21%).
The descendants of the bull Saluki 12638320 of the Chief 142738 line showed the lowest score for a complex of traits (80.11 points) and lower milk productivity indicators (yield - 9254 kg; fat - 3.80%; protein - 3.12%).
The established genetic influence on the linear exterior traits indicates the effectiveness of dairy cattle selection by type when using Holstein breed sires with high scores for the linear classification of their daughters' exterior. This confirms the effectiveness of dairy cattle selection by type, as it allows for the production of constitutionally strong and healthy animals with high milk productivity.
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