The fertilizing ability of stallion sperm after freezing is lower than in other species. The search for the optimal extender, combination of extenders, and the freezing protocol is relevant. The aim of this study was to compare lactose-chelate-citrate-yolk (LCCY) extender, usually used in Russia, and Steridyl® (Minitube) for freezing sperm of stallions. Steridyl is a concentrated extender medium for freezing ruminant semen. It already contains sterilized egg yolk. Semen was collected from nine stallions, aged from 7 to 12 years old. The total and progressive motility of sperm frozen in Steridyl was significantly higher than in semen frozen in LCCY. The number of spermatozoa with normal morphology in samples frozen in LCCY was 60.4 ± 1.72%, and with Steridyl, 72.4 ± 2.10% (p < 0.01). Semen frozen in Steridyl showed good stimulation of respiration by 2.4-DNP, which indicates that oxidative phosphorylation was retained after freezing–thawing. No differences among the extenders were seen with the DNA integrity of spermatozoa. Six out of ten (60%) mares were pregnant after artificial insemination (AI) by LCCY frozen semen, and 9/12 (75%) by Steridyl frozen semen. No differences among extenders were seen in pregnancy rate. In conclusion, Steridyl was proven to be a good diluent for freezing stallion semen, even though it was developed for ruminants.
One of the negative factors of ionizing radiation on the body is the formation of active oxidants, which are protected by the antioxidant system. The effect of high doses of radiation on the antioxidant system of animals has been studied well, but there is not enough information about the long‐term effects of low doses. The study of the effect of pre‐threshold radiation doses on the main indicators of antioxidant protection of cattle was the purpose of our research. The research was carried out in JSC "Osminskoye" of Slantsevsky district and JSC "Plemzavod " RAPTI" of Luga district of Leningrad region on healthy lactating cows aged 3–4 years in the amount of 8 heads from each farm. Radio ecological characteristics of agricultural land JSC "Osminskoe" was as follows‐the density of radioactive contamination of the soil on 137Cs more than 1 Ci/km2, the power of the exposure dose on the ground 35–48 μr/h. Similar indicators of land in JSC "Plemzavod" RAPTI " were less than 0.5 Ci/km2 and 6–19 μr / h. Both farms use their own fodder base (hay, silage, root crops), concentrated feed produced by JSC "LKKZ", the animals are kept in summer walking, which allows us to talk about a similar dose load due to external and internal irradiation. In cows, catalase activity was determined in serum, and malone dialdehyde concentration and superoxide dismutase activity were determined in plasma. The results of the study showed that the activity of superoxide dismutase in cows from JSC "Osminskoye" was 4.15±0.46 U/mg Hb, catalase ‐ 14.54±1.03 mkat/l, and the level of Malon aldehyde ‐ 3.71±0.68 μmol/l. Similar indicators in animals from JSC "Plemzavod "RAPTI" were as follows ‐ 6.3±0.75 U/mg Hb, 9.77±0.62 mkat/l and 2.23±0.12 μmol/l. Intergroup differences of the studied indicators were statistically significant. Analyzing the results of the study, we can say that chronic stimulation of the antioxidant system by active oxidants leads to a decrease in the level of superoxide dismutase in cows by 34.1%. Probably, as compensation, there is an activation of other enzymes, in particular, an increase in catalase activity by 1.5 times. However, the compensatory capabilities of other elements of the antioxidant system are not able to fully neutralize free radicals, as evidenced by an increase in the concentration of malon dialdehyde by 66.4%.The study shows that cows long‐term in conditions of higher pre‐threshold doses of external and internal radiation occurs chronic oxidative stress, manifested by an imbalance of individual links of the antioxidant system.
Cows that received an over-calorie diet in the final phase of lactation are prone to liver lipidosis. The task of our research is to study the dynamics of cholesterol and triglycerides in cows with fatty hepatosis during the transit period. A group of 20 dry cows was formed. In the blood serum of cows, the concentration of cholesterol and triglycerides was studied twice before calving (15–20 days and 5–10 days) and twice after calving (5–10 days and 20–25 days). After research was formed two groups. The first group included 8 cows, which were killed 7–43 days after calving. They had signs of liver lipidosis. The diagnosis of fatty hepatosis was confirmed by the results of a histological examination of the liver. The second group included the remaining 12 cows. At the beginning of the study, the cows of the first and second groups had a cholesterol concentration of 4.06±0.23 and 3.62±0.23 mmol/l, and triglycerides - 0.13±0.01 and 0.11±0.01 mmol/l. Further dynamics of indicators had features in each group. In cows with hepatosis, a gradual decrease in cholesterol to 1.83±0.07 mmol/l was observed. In the second group the indicator was 2.2 times higher (P < 0.01). Before calving, a decrease in the concentration of triglycerides is observed. A more significant decline was detected in cows of the first group—by 61.5% (P < 0.001). In cows of the second group, the index decreased only by 18.2%. After 5–10 days after calving, the concentration of triglycerides in both groups remained low. After 20–25 days in the first group, the index increased 2.3 times (P < 0.01), and in the second—1.25 times. Studies have revealed features of the lipid profile in cows with liver lipidosis.
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