The article suggests that one of the most widespread dairy breeds in the world is the Holstein breed; and the black-mottled breed in the Russian Federation. This breed has been improving during the past four decades by interbreeding it with the best one, the Holstein breed. A large set of the Holsteinized black-mottled livestock of the high thoroughbred cows of the Holstein breed has been produced. The aim of the work is to study the effect of age on the dynamics of dairy efficiency of the Holsteinized cows depending on the breeding line. At present, the dairy herd of the farm actually consists of cows of three breeding lines, Reflection Sovering 198998, Vis Back Ideal 1013415, Montvik Chieftain 95679. The rest breeds are not developing due to the absence of breeding valuable breeding bulls. It was found that the Reflection Sovering breeding line 198998 has that the highest milk yield during the sixth lactation, and then there is a decrease in milk yield. The article considers that the milk yield changes with age, starting from the first lactation, increasing during the second lactation and then it is gradually decreasing in productivity to the fifth one. The regularity of the increase in milk yield of mature cows during the third and fourth lactation is not confirmed of the dairy cows of this breeding line. It can be explained by the intensity of herb replacement, when it accumulates a significant amount of nutrients in the body. That is why, they can be used during the first and the second lactations without restoring nutrients in further. Dairy cows of the Vis Back Ideal 1013415 breeding line have a gradual increase in milk yield, starting from the first to the fourth lactation, by 52, 292, 300 kg or by 0.5; 2.8% and 2.8%, respectively. Further, there is a decrease in dairy efficiency. At reaching physiological maturity they have a natural increase in dairy efficiency. The same tendency is observed with cows of the Montvik Chieftein 95679 breeding line.
The increase in the productivity of cows is inseparably linked with the intensification of selection work with dairy cattle. All over the world, dairy cattle are used to obtain milk, including such related ones as black-and-white, Holstein, Dutch, which differ in economically useful qualities depending on the climatic and ecological-forage conditions of the breeding zone, and the gene pool of breed resources. Animal perfection is achieved by selecting the best males and females for reproduction and individual selection. The transmission of genes from generation to generation is carried out from father to son, from mother to son, from father to daughter, from mother to daughter. The rate of genetic improvement in dairy cattle populations depends on the efficiency of the assessment, selection and use of these groups of animals. Currently, the farm uses the daughters of sire bulls belonging to 3 Holstein lines. Several breeding bulls are used in each line. So, at present, the farm uses 17 bulls-sires of the Vis Back Aydial 1013415 line, 10 bulls of the Reflection Sovering 198998 line and 3 bulls of the Montvik Chief 95679 line, but the daughters of not all breeding bulls are already used in the herd. The belonging of cows to a certain line reliably at a high level of reliability influences the indicators of milk productivity. The decrease in milk yield in cows of the Montvik Chieftain 95679 line is accompanied by an improvement in the quality indicators of milk, namely, MJ in milk. Daughters of bulls-producers of a certain line differ in their productive qualities. The best indicators were found in the groups of daughters of sire bulls: Emen 105018721 and Pilot 63811814 (Reflection Sovering line 198998); Reverse 2708 (Montvik Chieftain line 95679); Tek 69052876 and Fennek 4241542328 (Vis Back Aydial line 1013415).
Live weight is an important indicator of livestock productivity and serves as an informative measure for the health, feeding, breeding, and selection of livestock. In this paper, the live weight of pig was estimated using six morphometric measurements, weight at birth, weight at weaning, and age at weaning. This study utilised a dataset including 340 pigs of the Duroc, Landrace, and Yorkshire breeds. In the present paper, we propose a comparative analysis of various machine learning methods using outlier detection, normalisation, hyperparameter optimisation, and stack generalisation to increase the accuracy of the predictions of the live weight of pigs. The performance of live weight prediction was assessed based on the evaluation criteria: the coefficient of determination, the root-mean-squared error, the mean absolute error, and the mean absolute percentage error. The performance measures in our experiments were also validated through 10-fold cross-validation to provide a robust model for predicting the pig live weight. The StackingRegressor model was found to provide the best results with an MAE of 4.331 and a MAPE of 4.296 on the test dataset.
The Ural type of the domestic black-and-white mottled breed features high productivity rates, good suitability for industrial milking technology, but the duration of its productive longevity is 2.4–2.6 lactations only, although in herds there are cows with productive longevity up to 10 lactations. The decline in productive longevity is associated in particular with reproductive qualities. As a result of the research, it was found that the Sealing Trijun Rockit cows proved to be the most resistant to their long use within the conditions of dairy farms for industrial milk production of pedigree reproducers; their productive longevity was 4.0 lactation. In other lines the productive longevity ranged from 1.8 (Pabst Governor line) to 2.5 (Montvic Chieftain line) lactations. A low fertility rate (less than 0.95) proves the existence of reproduction problems in the herd. Modern Holsteinized black-and-white mottled cattle bred in the Sverdlovsk region has high breeding qualities. The potential of their use is quite high and, despite certain reproduction problems, they are able to produce for a long time in the ecological and forage conditions of their breeding zone.
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