High Fertility Bulls Research Articles

Effects of sperm preparation and bull fertility on in vitro penetration of zona-free bovine oocytes

The objectives of this study were to develop and validate a zona-free bovine oocyte penetration assay for detecting relative differences in bovine sperm fertility and to determine the effect of different sperm preparation methods on oocyte penetration. Oocytes were incubated with heparin-capacitated spermatozoa which either were or were not induced to acrosome-react with lysophosphatidylcholine. Heparin-capacitated spermatozoa treated with lysophosphatidyl-choline penetrated more oocytes and had more penetrations per oocyte than spermatozoa capacitated in heparin but not induced to acrosome-react with lysophosphatidylcholine. Spermatozoa stained with Hoechst 33342, fluorescein isothiocyanate or tetramethyl rhodamine isothiocyanate, alone or in combination, penetrated similar numbers and percentages of zona-free bovine oocytes as the similar to nonstained spermatozoa. When spermatozoa from the same ejaculate were stained with either fluorescein isothiocyanate or tetramethyl rhodamine isothiocyanate and competed in penetrating the same oocytes, the number of penetrations generated by the 2 differently stained spermatozoa was similar. Spermatozoa from bulls of differing in vivo fertilities were labeled with different fluorescent dyes, and their relative abilities to penetrate the same oocytes were assessed. Comparisons between spermatozoa from high and low fertility bulls demonstrated that high fertility spermatozoa had a significant oocyte penetrating advantage over low fertility spermatozoa in 13 of 16 paired competitions. We concluded that the results of the competitive penetration of zona-free bovine oocytes by fluorochrome-labeled spermatozoa from bulls of different fertilities were indicative of their relative in vivo fertility.

Effect of accessory sex gland fluid from bulls of differing fertilities on the ability of cauda epididymal sperm to penetrate zona-free bovine oocytes.

The ability of accessory sex gland fluid to affect the fertility of cauda epididymal sperm was evaluated for 10 bulls that ranged in fertility from 6.2% below to 6.0% above the average fertility of bulls at artificial breeding cooperatives. Cauda epididymal sperm collected from indwelling vasa deferentia catheters and cauda epididymal sperm exposed to accessory sex gland fluid from the same bull were compared on the basis of their rates of in vitro penetration of zona-free oocytes after heterospermic insemination. Incubation of cauda epididymal sperm with accessory sex gland fluid significantly enhanced the ability to penetrate oocytes, and bull fertility affected the magnitude of this improvement. For bulls of average and higher fertility, the positive influence of accessory sex gland fluid on penetrating ability of sperm was highly significant (p < 0.0001). Accessory sex gland fluid from bulls of below-average fertility also improved the penetrating ability of cauda epididymal sperm, although not significantly (p = 0.07). Heterospermic competitions compared the penetrating ability of cauda epididymal sperm exposed to homologous accessory sex gland fluid with a portion of the same sperm population incubated in heterologous accessory sex gland fluid from a bull of contrasting fertility. In experiments involving sperm from 12 different bulls, paired in 42 fertile/subfertile combinations, samples of cauda epididymal sperm mixed with accessory sex gland fluid from the higher-fertility bulls had greater oocyte-penetrating ability than when aliquots of that sample were mixed with accessory gland fluid from lower-fertility bulls (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Paternal Influence on S-Phase in the First Cell Cycle of the Bovine Embryo1

The objective of this study was to determine whether the initiation and length of the zygotic S-phase differs for embryos sired by bulls demonstrating high versus low fertility in vivo. Bovine oocytes were matured in vitro for 24-27 h and fertilized with frozen-thawed bovine semen. Six bulls that differed in fertility level were used in the study. The bulls were classified into two groups: those demonstrating high fertility in vivo (in vivo high-fertility bulls; n = 3), with a group mean +/- SEM lifetime nonreturn rate of 78 +/- 2%, and those demonstrating low fertility in vivo (low-fertility bulls; n = 3), with a group mean +/- SEM nonreturn rate of 69 +/- 1%. The S-phase in zygotes was identified by means of an immunocytochemical technique after pronuclear-stage zygotes were labeled with 5'bromo-2'deoxyuridine (BrdU). To visualize all pronuclei, presumptive zygotes were also stained with propidium iodide. In the first experiment, zygotes were labeled with BrdU at 2-h intervals from 8 to 20 h after sperm addition. There were no differences between bull fertility groups in the time course of pronuclear formation (p > 0.05). The beginning of S-phase was earlier in zygotes sired by high- compared to low-fertility bulls (p < 0.05). The end of S-phase was not affected by sire fertility group (p > 0.05). In the second experiment, zygotes were labeled with BrdU continuously from 8 to 20 h after sperm addition.(ABSTRACT TRUNCATED AT 250 WORDS)

Fertility-Associated Proteins in Holstein Bull Seminal Plasma1

This study was undertaken to determine whether bovine seminal plasma contained protein markers associated with bull fertility, and whether these markers were of value in predicting bull fertility. Seminal plasma was obtained from 35 Holstein bulls of known fertility. Two-dimensional PAGE of seminal plasma samples indicated that two proteins (26 kDa, pI 6.2; 55 kDa, pI 4.5) predominated in higher-fertility bulls, and two proteins (16 kDa, pI 4.1; 16 kDa, pI 6.7) predominated in lower-fertility bulls. Densitometry data for these proteins in individual samples were combined for bulls grouped by fertility level. Average density of the 26-kDa protein was significantly greater in seminal plasma of high-fertility bulls, and high-fertility seminal plasma also contained more of the 55-kDa protein than that of average- and below average-fertility bulls. Below average- and low-fertility bull seminal plasma had significantly more of both 16-kDa proteins than that of average- and high-fertility bulls. A regression model was developed to predict bull fertility using the four fertility-associated protein densities. A plot of actual bull fertility versus that calculated by this model was linear and positively correlated (r = 0.89). These findings indicate that bull seminal plasma contains fertility-associated proteins that are predictive of bull fertility.

The Effect of Whole Ejaculate Filtration on the Morphology and the Fertility of Bovine Semen

A Sephadex G-15 filtration method was developed to remove abnormal and nonmotile bull sperm from an entire ejaculate. The efficiency of filtration was determined by adding freeze-killed sperm to the ejaculate or using ejaculates with elevated numbers of abnormal cells induced by scrotal insulation. A fertility trial, using split ejaculates, compared fertility of filtered and unfiltered semen.After filtration, samples with 0, 25, and 50% killed cells added contained 77 to 81% motile cells. Addition of 75% killed sperm resulted in significant decrease (52%) of motile cells following filtration. Morphologic examination of semen with elevated numbers of abnormal cells revealed higher percentages of sperm with normal shaped heads and normal or swollen acrosomes after filtration than in unfiltered samples. Percentage of pear-shaped heads, lifted acrosomes, and bent tails decreased after filtration. Six high fertility and six low fertility bulls were used to evaluate fertility of filtered semen. Filtering increased motile sperm from 51 to 57% and from 36 to 50% for the high and low fertility bulls, respectively. The 60- to 90-d nonreturn rates for high fertility bulls were not increased by filtering (73 vs. 72%). However, filtering significantly improved the nonreturn rates for the low fertility bulls (61 vs. 67%).

Transport and Fate of Spermatozoa After Insemination of Cattle

Sperm capable of fertilizing ova reach the isthmus of cows about 8h after mating and remain in the caudal 2cm of the isthmus until ovulation. Then small numbers of sperm move to the site of fertilization at the junction of the isthmus and ampulla.Within a few hours after deposition of semen in the uterine body, most sperm have drained to the exterior in cervical mucus. By 12 to 24h after insemination, only a few percent of the sperm remain in the reproductive tract, and most of these are in the vagina.Contractions of the reproductive tract appear to be the primary mechanism of sperm transport. Flagellation of sperm is probably required for sperm to enter the folds of the cervix, and flagellation may be helpful or essential for sperm to pass through the uterotubal junction, move from the isthmus to the ampulla, and penetrate ova. High proportions of sperm undergo the acrosome reaction only in the ampulla on the side of ovulation and only after ovulation.The fertilization rate in cattle can be improved by use of semen from high fertility bulls and perhaps by timing insemination with semen from lower fertility bulls after the end of estrus.

Dilauroylphosphatidylcholine liposome effects on the acrosome reaction and in vitro penetration of zona-free hamster eggs by bull sperm: II. A fertility assay for frozen-thawed semen.

Frozen-thawed sperm from five bulls with fertility rates ranging from 48% to 77% were treated with seven concentrations of dilauroylphosphatidylcholine (PC12) liposomes to induce an acrosome reaction (AR) that enabled sperm to penetrate eggs. Treated sperm were incubated with liposomes for 7 min prior to insemination of zona-free hamster eggs in vitro. Sperm and eggs were incubated 3 hr at 39 degrees C prior to fixation, staining, and examination for sperm penetration and nuclear decondensation. The percentage of motile sperm immediately after thawing as well as after treatment with liposomes had a low correlation with sire fertility (r = .39 and less than or equal to .63, respectively). The percentage of sperm exhibiting an AR was more highly correlated with fertility (r less than or equal to -.85). Similar correlations were found between fertility and the penetration rates of zona-free hamster eggs or the total number of penetrating sperm. When data for two high and for two lower fertility bulls were each grouped to increase information per data point the correlation between the PC12 concentration giving the maximum proportion of eggs penetrated and fertility was r = .92 (P less than .05). The correlation between the PC12 concentration producing the most total sperm penetrating the eggs and fertility r = .97 (P less than .05). It was concluded that PC12 liposomes induced an AR in bull sperm frozen-thawed in egg yolk extender. Frozen-thawed sperm from low fertility bulls require less PC12 to induce the AR and to penetrate zona-free hamster eggs than do sperm from higher fertility bulls. These differences in lipid requirements may help to provide a quick, direct laboratory assay method to estimate the fertility of frozen bull semen.

Dilauroylphosphatidylcholine liposome effects on the acrosome reaction and in vitro penetration of zona-free hamster eggs by bull sperm: I. A fertility assay for fresh semen.

Fresh sperm from five bulls having nonreturn rates ranging from 48% to 77% were treated with 15.7, 21.0, 26.2, 31.5, 36.7, and 42.0 microM dilauroylphosphatidylcholine (PC12) to induce the sperm acrosome reaction (AR). Treated sperm were incubated 3 hr with zona-free hamster eggs at 39 degrees C prior to fixation. The eggs were then stained and examined for sperm penetration. Differences in the percentages of motile sperm and of sperm exhibiting an AR among bulls were small when compared on a within-liposome-concentration basis. Increasing the PC12 concentration from 15.7 microM to 42.0 microM increased the percentage of sperm exhibiting an AR for all bulls. At the lowest lipid concentration (15.7 microM), the percentage of eggs penetrated by sperm from the five bulls was 6% to 36%, with 0% in controls. When sperm were incubated with increasing lipid concentrations, the egg penetration rate increased to over 80%, and the total number of sperm increased to over 100 per 36 eggs in each treatment for every bull. These penetration rates decreased at the highest lipid concentration. A correlation between the PC12 concentration maximizing egg penetration and the nonreturn rate of -.63 was found. The correlation between the PC12 concentration maximizing the total number of penetrated sperm per treatment and the bull nonreturn rate was -.96. It was concluded that PC12 liposomes induce the AR in bull spermatozoa, which enables them to penetrate zona-free hamster eggs. High fertility bulls required less lipid to induce the AR than did lower fertility bulls. Consequently, this assay of fresh semen could provide a laboratory method to estimate the fertility of a bull.

Relationship of Nonreturn Rates of Dairy Bulls to Binding Affinity of Heparin to Sperm

The binding of the glycosaminoglycan [3H] heparin to bull spermatozoa was compared with nonreturn rates of dairy bulls. Semen samples from five bulls above and five bulls below an average 71% nonreturn rate were used. Samples consisted of first and second ejaculates on a single day collected 1 d/wk for up to 5 consecutive wk. Saturation binding assays using [3H] heparin were performed to quantitate the binding characteristics of each sample. Scatchard plot analyses indicated a significant difference in the binding affinity for [3H] heparin between bulls of high and low fertility. Dissociation constants were 69.0 and 119.3pmol for bulls of high and low fertility, respectively. In contrast, the number of binding sites for [3H] heparin did not differ significantly among bulls. Differences in binding affinity of [3H] heparin to bull sperm might be used to predict relative fertility of dairy bulls.

Metabolism of Bull Semen. I. Inorganic and Total Phosphorus Relationships

Summary Inorganic and total phosphorus determinations on 506 semen samples collected over a 7-month period from 36 bulls of high fertility showed a marked relationship between sperm concentration and total phosphorus (r=0.88). Inorganic phosphorus content of semen before and after incubation for 1hour at 37° C. was most closely correlated with sperm concentration (r=0.23) and showed unimportant relationships with initial motility, fructose, and fructose utilization. Inorganic phosphorus increased 1.4mg. % or 8.2% (P

Diluters for Bovine Semen. V. A Comparison of Heated Milk and Egg Yolk-Citrate as Diluters for Semen from Bulls of High and Low Fertility

Diluters for Bovine Semen. V. A Comparison of Heated Milk and Egg Yolk-Citrate as Diluters for Semen from Bulls of High and Low Fertility

Service Sire Influences on Fertility Rates of Repeat Breedings

Summary Data from 6,232 inseminations with semen of 39 bulls by one man in one area of Washington from August 1949 through October 1951 were used for this study. No important breed differences with respect to 180-day nonreturn rates or average repeat service intervals were present. High fertility bulls showed a 180-day nonreturn first service rate of 70 per cent compared with 63 and 59 per cent, respectively, for medium and low fertility bulls. The fertility level of the bull had a marked effect on the fertility of repeat services with semen from other bulls. Low fertility bulls were 17 per cent below their first service average when bred to repeats of low fertility bulls but only 4–5 per cent lower when following medium and high fertility bulls. The fertility of repeat services by high fertility bulls was −1, −4, and −7 per cent lower, respectively, when they followed bulls of high, medium and low fertility. These results are in agreement with those of Christian and Casida (1), and it is concluded that the low fertility bull lowers the fertility of repeat service cows, even though repeat services are with semen from high fertility bulls.

The Fertility of Bovine Semen in Extenders Containing Sulfanilamide, Penicillin, Streptomycin and Polymyxin

Summary By use of the split sample technique the fertility of bovine semen extended in 3.6 per cent citrate-yolk containing no antibacterial agent, sulfanilamide, penicillin, streptomycin, polymyxin or a combination of these four antibacterial agents was studied. Semen was used from bulls with histories of low fertility, as well as from bulls with histories of high fertility. The per cent 60- to 90-day non-returns to first and second service cows for the treatments, no antibacterial agent, sulfanilamide, penicillin, streptomycin, polymyxin, and sulfanilamide plus penicillin plus streptomycin plus polymyxin were, respectively, for the high fertility bulls, 63, 64, 70, 69, 68, and 67; for the low fertility bulls, 58, 60, 67, 66, 59, and 69 and for both the high fertility and the low fertility bulls combined, 61, 62, 68, 68, 64, and 68. On the bases of these results and those reported by other workers, it is concluded that the addition of penicillin, streptomycin or a combination of these plus polymyxin and sulfanilamide to present day extenders may be expected to increase the over-all fertility level of bovine semen used for artificial breeding.