PECULIARITIES OF THE BEHAVIOR OF BULLS-CALFS OF UKRAINIAN GRAY BREED AND ITS RELATIONSHIP WITH LIVE WEIGHT GAINS
Authors: Kozyr V. S. , Denysiuk O. V. 
Published: July 2023

Introduction. In cattle breeding the increase in live weight gains is an important factor in the growth of the industry's efficiency. Ethological characteristics of animals play a significant role in this process. The purpose of the work is to find out the peculiarities of the behavior of bull-calfs of the Gray Ukrainian breed in untethered housing and its relationship with live weight gains. The results of studies of the ethological characteristics of bull- calfs of the Gray Ukrainian breed and their the dynamics of live mass in early ontogenesis under the conditions of untethered keeping in walking areas are presented. Materials and methods of research. The research was carried out at the SЕ RF «Polyvanivka» SE of the NAAS (Dnipropetrovsk region) – a breeding plant for breeding gray ukrainian cattle. Ethological assessment of animals was carried out taking into account feeding, braking and motor behavior, functional activity indices (T) were calculated.

The development of animals was evaluated by the live weight of newborn calves at 12 and 15 months of age, average daily gains were calculated, the level of correlations between traits and the strength of the influence of feeding behavior on productivity were determined according to generally accepted methods. Research results. During the research period (from 8:00 to 8:00), young animals spent 10.3% of the total observation time moving around the corral. Moreover, motor activity changed during the day, which increased between 11:00–12:00 p.m. and 17:00–18:00. They spent 38.5% of the observation time on rest. Animals spent 210 minutes or 29% of the time lying down (resting and chewing) preferring a dry, straw-covered floor. This fact must be taken into account in order to ensure comfortable conditions for animals. Young have good indicators of individual development. The average live weight of newborn, 8- and 15-month-old bulls-calfs was 27.5 ± 0.20 kg, 175.2 ± 0.20 kg and 347.3 ± 5.50 kg, respectively. The average daily gain for the period from birth to 15 months of age was 0.710 ± 0 0121 kg.

When dividing the animals into classes according to their foraging behavior, a significant reliable difference between the groups  and the duration of foraging was established. Thus, the young belonging to the class M+ spent more time "eating fodder", eating "juicy" and "juicy + coarse" fodder compared to peers from the class M-. The indicators of the index of functional activity in them were higher by 0.0868 units (Р > 0.999), 0.051 (Р > 0.99) and 0.0254 untis (P > 0,95), respectively. According to other ethological reactions, the difference is insignificant or unreliable. In accordance with this, the indicators of the development of animals of the Gray Ukrainian breed of cattle at the age of 15 months were established. The research results show that the highest average indicators of live weight (376.7 ± 4.01 kg) and average daily gains (0.775 ± 0.0091 kg) are characterized by 15-month-old bull-calfs, which belong to the class M+. The young belonging to the class M0 had a live weight of 346.9 ± 2.98 kg and an average daily gain of 0.709 ± 0.0069 kg. Thus, studies show that steers of different classes of distribution according to indices of functional activity of foraging behavior had unequal live weight.

Analyzing the correlation between elements of bull-calfs behavior and growth indicators, a reliable positive relationship was established between the time spent on: eating feed × live weight (r = 0.95, Р > 0.999), eating juicy feed × live weight (r = 0.65, P > 0.999), eating juicy + roughage × live weight (r = 0.59, P > 0.999). In others, it was insignificant or not reliable. The effect of individual elements of behavior on the intensity of animal growth in early ontogeny was proven by the conducted one-factor variance analysis. Thus, the power of influence (ηχ2) of foraging behavior (index of functional activity "forage eating") in the total sum of all factors on the live weight of steers at the age of 15 months is 0.886 or 88.6%. Thus, the formation of technological groups and the selection of young animals in the early ontogeny for fattening with additional consideration of their behavior will allow to better realize the genetic potential and increase the level of profitability of beef production.

Conclusions. It was established that bul-calfls of the Gray Ukrainian breed have individual characteristics of behavior (time spent on "foraging activities" – 368.3 ± 8.15 min (xmin–290; xmax–430), "eating feed" – 251.75 ± 6.03 min (xmin – 190; xmax – 285), “movement” – 74.3 ± 3.17 min (xmin – 50; xmax – 105) etc. The development of bul-calfls in early ontogenesis is significantly influenced by their ethological reactions. In the total sum of all factors affecting live weight of bull-calfs at 15 months of age, the share of influence of foraging behavior (index of functional activity "forage eating") is 88.6% (ηχ2 = 0.886). The foraging behavior of young animals is highly correlated with their live weight at 15 months of age. The relationship between pairs of traits is: "eating feed" × "live weight" – r = 0.95 (Р > 0.999), "eating juicy feed" × "live weight" – r = 0.65 (Р > 0.999) , "eating juicy + roughage" × "live weight" – r = 0.59 (Р > 0.999). Bulls-calfs that were more active in feed consumption (M+; T = 0.3889 ± 0.00359) compared to peers (M-; T = 0.3021 ± 0.00961) have higher live weight indicators at 15 months of age by 58.4 kg (Р > 0.999) and average daily increase– by 0.128 kg (Р > 0.999).