Vol 108, No 1 (2025)

In the last few years, there has been a growing interest in the use of natural feed additives in animal feed. In particular, the prospects of using ultrafine particles as a substitute for antibiotics to change fermentation in the rumen and increase the efficiency of feeding ruminants are shown. The purpose of our study was to evaluate a sulfur-containing organomineral complex based on amino acids and Na₂SO₄ for the effectiveness of rumen digestion by the in situ method in its pure form and in combination with UFP SiO₂. The study was conducted on Kazakh white-headed bull calves with chronic fistula. 3 groups were formed for in situ testing: I – control; II – amino acid complex (tryptophan, lysine, methionine) + Na₂SO₄; III – amino acid complex (tryptophan, lysine, methionine) + Na₂SO₄ + UFP SiO₂. The study showed an increase in the coefficient of digestibility in groups II and III by 3.7 and 2.6% compared with the control. The analysis of volatile fatty acids showed an increase in the concentrations of acetic, propionic, and butyric acids by 112, 77.7, and 76.8% in group I and by 44.3; 4.52% and 32.6% were in II, respectively. Changes in protein metabolism were associated with an increase in protein and non-protein nitrogen in group I compared with the control by 85.6% and 52.3%. The study demonstrated the beneficial effect of combined use of the studied substances on the processes of rumen digestion. The combined use of an ultrafine form of silicon dioxide, an amino acid complex, and sodium sulfate proved to be effective in stimulating rumen digestion.

The modern development of poultry breeding is marked by genetic and breeding achievements aimed at increasing productivity and reducing rearing time. Prospects of modern research are directed to the search for new technologies that contribute to the increase of organism resistance and reveal genetic potential. The presented review systematizes data on structural and functional features of the immune system of poultry, considers etiological factors of immunosuppression and analyzes determinants affecting the formation of nonspecific resistance of the organism. The data on the key role of essential trace elements, including zinc, selenium, iron, iodine, manganese and copper, in the regulation of immune status are presented.

The modern population of the Simmental breed in Russia is represented by different genotypes, and further breeding work is focused on obtaining animals mainly of dairy and meat direction of productivity using both domestic and imported sires of German and Austrian breeding. The combination of high milk productivity and good reproductive function of cows is an important criterion in breeding work with dairy cattle in general and in assessing their breeding value. Daughters born from Simmental bulls of local origin reach the age of fruitful insemination later (the age of the 1st calving is 32.5 months) and have a significantly shorter service period and intercalving period - 134.1 and 413 days, respectively, on average for three lactations, relative to the daughters from sires of Holstein lines and German-Austrian lines of imported origin. The value of the service period decreases with age regardless of the type of breeding orientation of the line: for the 1st lactation - 139.6...161.1 days, for the 2nd lactation – 131.3...148.7, for the 3rd lactation – 122.4...146.9 days. The study of indicators characterizing the reproductive function of Simmental cows obtained from local and imported breeding sires is an important aspect for evaluating and optimizing breeding work and allows us to determine the influence of the genotype of fathers on the reproductive potential of daughters.

Blood testing of beef cattle is relevant due to the peculiarities of keeping animals in conditions requiring a high level of adaptation. Hereford cattle tolerate extremely low and high temperatures well; however, for breeding cattle it is important to evaluate animals not only by productivity, but also by interior features, including hematological parameters. The aim of the study was a comparative assessment of the blood parameters of breeding cattle of the Hereford breed in the parental and daughter generations. The study was conducted in a breeding farm located in the foothill zone of the Maslyaninsky District of the Novosibirsk Region. The object of the study was the hematological parameters of peripheral blood of Hereford cows and heifers (mother-daughter pairs) kept outdoors all year round in the foothill pastures of the south of Western Siberia. The age of the cows was 3-5 calving, the age of the heifers was 17-18 months. Blood counts in the maternal and daughter generations were analyzed, and the total number of parent-descendant pairs was 66 pairs. It has been established that the hematological parameters of cows and heifers in the conditions of foothill pastures in the south of Western Siberia are within the reference values with a sufficiently high variability of all signs. Significant differences between the indicators of mothers and daughters under the condition of the same type of maintenance, feeding and the period of blood sampling indicate the presence of the influence of the age of animals rather than environmental conditions. At the same time, a fairly high level of heritability of hematological parameters was found, primarily related to the blood's ability to transport oxygen, which can be used as a criterion for the animals' adaptability to extreme conditions.

In the agro-industrial complex, in the conditions of an increasing number of extremely high summer droughts, there is an objective need for structurally significant changes in the feed production feedstock conveyor by introducing non-traditional drought-resistant forage crops - Sudan grass, sorghum and sorghum-Sudan hybrids, as well as forage crops with a short growing season for an uninterrupted supply of livestock with feed. Under heat stress, it is important to use properly selected high-quality feed and special feed additives that reduce the production of metabolic heat in the body, as well as to adjust feeding regimes, monitor the level of the temperature-humidity index, the indicators of which will allow a timely assessment of the need for cooling of animals. The article presents overview information on the state of forage production and livestock farming in conditions of extremely high temperatures. The papers of Russian and foreign authors on various practical strategies for mitigating the effects of heat stress in the maintenance and feeding of cows, which may be useful to specialists in the field of dairy farming, were reviewed.

Modern methods of feeding dairy cattle, including year-round uniform feeding, are not always optimal for ruminants, which can lead to a decrease in the efficiency of nutrient absorption, especially with excessive intake of concentrated feeds, in which a large amount of lactic acid is formed in the rumen microbiome as a result of carbohydrate fermentation, which has a negative effect on the metabolism, structure and function of internal organs. One of the possible solutions to this problem in feeding highly productive cows is a targeted effect on the symbiotic microflora of the forestomachs by feeding probiotic preparations. In this regard, the aim of our research was to study the effect of the enzyme-probiotic feed additive Profort on the metabolic status, milk productivity and milk quality of lactating cows under conditions of year-round uniform feeding. Analysis of the milk productivity of cows after the first feeding (within 15 days) of Profort showed that the average daily milk yield in animals increased by 6.1%, compared with animals in the control group. Milk productivity of cows after repeated feeding of the preparation remained higher by 4.6 % than in the control animals. After the end of the experiment and the next feeding of the preparation, the difference in average daily milk yield was 1.9 kg (4.9%) in favor of the cows of the experimental group. Gross milk yield during the experiment in the experimental group was higher by 5.94%. The use of the enzyme-pobiotic feed additive Profort improves liver function in lactating cows. Total protein indicators increased by 1.46%, albumins - by 16.5% (P≤0.05), AST activity decreased by 15% (P≤0.05) and ALT - by 17.5%; the level of urea, triglycerides and cholesterol decreased by 11, 20 and 30.5%, respectively, which indicates an improvement in the metabolic state.

Complete balanced feeding of animals is one of the fundamental moments in increasing the production of livestock products and their quality indicators. In poultry farming, along with increasing productivity, an important task is the prevention of various diseases, in particular coccidiosis. The article presents the results of studies on the combined use of the prebiotic additive "LactuSuper" and the new anticoccidial drug Eimicide in feeding broiler chickens and their impact on growth rates, intestinal microbiome, development of the digestive organs and slaughter characteristics. As a result of the research, it was found that the combined use of anticoccidial and prebiotic preparations in broiler diets is more effective than separately, since the experimental animals of this particular group were distinguished by greater survival, average daily live weight gain, total microbial count in the blind processes of broiler chickens with a predominance of beneficial microflora, and all corrective changes in the mass of organs were aimed at strengthening the microbiocenosis of intestinal microflora, which contributed to obtaining a greater yield of carcasses, offal and edible parts of the carcass.

The article analyzes data on the assessment of the digestibility of the ready-made Grand Prix diet based on turkey and beef in service dogs. The study found that the nutritional value, taking into account the digestibility of the ready-made diet, was not satisfied in all dogs of the analyzed sample: the protein digestibility coefficient averaged 39.04% in service dogs of the German Shepherd breed and 48.44% in dogs of the Belgian Shepherd breed (Malinois). The amount of fat in the ready-made diet was on average 2.6 times higher than the daily requirement of animals with a digestibility of 89.00%. The total digestibility coefficient for the main components of the feed was 63.54 % for the German Shepherd and 68.41% for the Belgian Shepherd (Malinois), while the calculated indicator according to the manufacturer was 88.09 %. Problematic issues of the practice of choosing food for service dogs according to the degree of digestibility are formulated.

The work is devoted to the problems of assessing the dependence of durum wheat productivity on a number of factors in unstable climatic conditions. In the presented work, the influence of air temperature, precipitation, dry wind days, cellulolytic activity and nitrate nitrogen content in the soil on the productivity of durum wheat in the system of six-field, two-field crop rotations and monoculture in the arid conditions of the Southern Urals was studied for the first time. Field experiments were carried out on a long-term experimental plot for crop rotations and monocultures. Durum wheat crops were placed in crop rotations and monoculture near the village of Nezhinka, Orenburg region (coordinates: 51.775125^o N and 55.306547^o E). Research (2002-2022) established average values ​​of air temperature - 5.7-22.7 °C, precipitation - 22-364 mm, number of dry wind days - 68, cellulolytic activity of the soil - 0.69-0.76%, nitrate nitrogen content - 0.32-0.75 mg/100 g of soil, crop yield - 0.48-0.97 t/ha. A correlation was found between grain yield and air temperature in May, June (r = 0.49-0.65) and during the growing season (r = 0.40-0.47), with precipitation in May, June (r = 0.33-0.67) and during May-August (r = 0.44-0.60), with the number of dry wind days (r = 0.30-0.41), with the hydrothermal coefficient in May, June (r = 0.41-0.76) and during the growing season (r = 0.50-0.66). The lowest relationship between weather factors and yield was noted in July and August. A weak relationship was found between cellulolytic activity of the soil and yield (r = 0.17-0.31). A weak dependence of grain yield on the nitrate nitrogen content in the soil after sowing the crop (r = 0.13-0.34) and the difference (N-NO₃) during the growing season (r = 0.01-0.17) was noted. In the arid conditions of the Southern Urals, a slowdown in the vital activity of microflora is noted due to a lack of soil moisture, which contributes to a decrease in the relationship between cellulolytic activity and the yield of spring durum wheat. Thus, weather conditions are fundamental in the formation of the yield of spring durum wheat.