Effect of using liquid semen on fertility in German Holstein Friesian dairy cattle: A randomized controlled clinical trial.

Low fertility rates in lactating dairy cows as well as restricted availability of semen doses of young bulls with high genetic merit are two major problems in the reproduction of dairy cows. By using liquid semen (LS), the number of doses per ejaculate can be increased. One of the challenges of optimizing the reproductive performance of dairy cows is the phenomenon of variable estrus lengths. The objective of this study was to determine whether the use of LS affects pregnancy outcome of dairy cows with delayed ovulation, when compared with frozen semen (FS). A randomized controlled clinical trial was implemented. In a split-sample procedure, 131 ejaculates were processed into LS (Caprogen, LIC, New Zealand) and FS (BioXcell, IMV, France). Both semen types of each ejaculate were inseminated under the same field conditions to cows showing natural or induced heat. Cows and semen type were allocated according to the last digit of the cows identification number (even = frozen semen, odd = liquid semen). Inseminations (n = 667) were conducted after localization of the pre-ovulatory follicle. Determination of ovulation was performed 24 h post AI per transrectal ultrasonographic examination. Ovulations were classified as delayed when the pre-ovulatory follicle was still present at ovulation control. The prevalence of delayed ovulations was 25.2%. Data of 667 inseminations were analyzed with a generalized linear mixed model including semen type (P = 0.016), parity (P = 0.014), backfat thickness (P = 0.006), estrus induction (P = 0.010), ovulation (P = 0.265) and the interaction term 'semen type by ovulation' (P = 0.094). Overall, a higher pregnancy per AI (P/AI) of LS (45.4%) than P/AI of FS (33.7%) was found. In cases of delayed ovulations, use of LS resulted in higher P/AI (46.8%) compared with FS (27.7%; P = 0.017). We concluded that the fertilizing capacity of LS in prolonged intervals from AI to ovulation might be greater when compared with FS and could be an efficient tool to improve fertility of lactating dairy cows with delayed ovulations.

Inter- and intra-individual variability of total antioxidant capacity of bovine seminal plasma and relationships with sperm quality before and after cryopreservation.

The aim of the present study was to investigate inter- and intra-individual variability of total antioxidant capacity (TAC) in seminal plasma of bulls. In addition, relationships between TAC and glutathione peroxidase (GPx), superoxide dismutase activities (SOD), and parameters of sperm quality, respectively, were examined. Eight consecutive ejaculates were collected from nine Holstein-Friesian bulls. The percentage of plasma membrane and acrosome intact (PMAI) sperm was measured by using the FITC-PNA/PI assay, the amount of membrane lipid peroxidation (LPO) without and with stimulation(s) of LPO was quantified by using the BODIPY assay before cryopreservation and immediately (0 h) as well as 3h after thawing. The percentage of sperm with a greater DNA fragmentation index was measured by the sperm chromatin structure assay. The amount of TAC differed (P < 0.0001) between bulls but not (P > 0.05) between ejaculates within bulls. The amounts of TAC were not related (P > 0.05) to amounts of SOD and GPx, but were negatively associated with LPO 0 h (r = -0.85; P ≤ 0.01). The amounts of SOD showed positive relationships with LPO 0 h (r = 0.71; P ≤ 0.05) and LPO 3h (r = 0.80; P ≤ 0.05). In conclusion, total antioxidant activity varied among bulls, but not between ejaculates within bulls. While the amounts of antioxidative enzyme GPx was not related to sperm quality and SOD was positively related with lipid peroxidation after thawing of sperm, whereas total antioxidative capacity was negatively correlated with lipid peroxidation of cryopreserved sperm.

Effects of feeding omega-3-fatty acids on fatty acid composition and quality of bovine sperm and on antioxidative capacity of bovine seminal plasma.

The aim of the present study was to examine the effects of feeding alpha-linolenic (ALA) acid on fatty acid composition and quality of bovine sperm and on antioxidative capacity of seminal plasma. Nine bulls (ALA bulls) were fed with 800 g rumen-resistant linseed oil with a content of 50% linolenic acid and eight bulls with 400 g palmitic acid (PA bulls). Sperm quality was evaluated for plasma membrane and acrosome intact sperm (PMAI), the amount of membrane lipid peroxidation (LPO), and the percentage of sperm with a high DNA fragmentation index (DFI). Fatty acid content of sperm was determined using gas chromatography. Total antioxidant capacity, glutathione peroxidase, and superoxide dismutase activity were determined in seminal plasma. Feeding ALA increased (P < 0.05) the docosahexaenoic acid (DHA) content in bulls whereas in PA bulls did not change. PMAI increased after cryopreservation in ALA bulls as well as in PA bulls during the experiment period (P < 0.005). LPO of sperm directly after thawing did not change during the study period in ALA group, but decreased in PA group (P < 0.006). After 3h of incubation LPO increased in the ALA group (P < 0.02), while LPO did not differ between phases within groups. In conclusion, feeding of neither saturated nor polyunsaturated fatty acids affect the antioxidant levels in seminal plasma. Both saturated as well as polyunsaturated fatty acids had positive effects on quality of cryopreserved bovine sperm, although the content of docosahexaenoic acid in sperm membranes increased only in ALA bulls.