Comparison of sperm quality of Belgian Blue and Holstein Friesian bulls

Few data are currently available on sperm quality of Belgian Blue (BB) bulls. The present study compared sperm quality of BB to Holstein Friesian (HF) bulls of several age categories, by means of a classical semen evaluation. Volume and concentration, and consequently total sperm output depended largely on age. Gross, total, and progressive motility, % live and % normal spermatozoa were significantly lower in the BB breed. Primary sperm abnormalities, such as nuclear vacuoles, midpiece defects and cytoplasmic droplets which were noticed most frequently, occurred far more in the BB breed. Hence, disturbances in spermiogenesis are deemed to be the cause of the poorer BB sperm quality. Since these sperm abnormalities occur significantly more in the BB breed than in the HF breed, it seems as if the BB breed is genetically predisposed to a higher susceptibility to environmental stresses which are known to interfere with normal spermiogenesis. The small scrota typical of the inbred BB breed might in part be responsible for this, and therefore selection for larger scrota in the BB breed is advisable.     

Breeding soundness, libido and performance of beef bulls mated to estrus synchronized females

Ninety-three beef bulls and 2316 females were used to determine the relationships between breeding assessments of bulls and subsequent mating performance. Each bull was given a breeding soundness examination (BSE) and two 10-min libido/serving capacity (L/SC) tests. Breeding potential of each bull was classified as satisfactory (BSE score = 60 to 100) or questionable (BSE score = 30 to 59); libido was classified as either high (mean score = 9.0 to 10) or medium (mean score = 6.0 to 8.5). Bulls were then joined, single-sire, with groups of females which had received one of two treatments to synchronize estrus. Bull-to-female ratios ranged from 1:7 to 1:51. Continuous observations were conducted on the mating activity of each group. One bull was removed from the experiment due to a severe breeding problem. Bulls of satisfactory breeding potential (n = 80) did not differ (P > 0.10) from bulls of questionable breeding potential (n = 12) in measurements of mating activity. However, by the end of the synchronized breeding period, bulls classified as satisfactory breeders achieved approximately a 9% higher (P < 0.10) pregnancy rate than did bulls of questionable breeding status (45.6 +/- 2.1% vx 36.5 +/- 5.3%). Bulls with a high libido (n = 69) serviced more (P < 0.01) estrous females (81.3 +/- 3.1% vs 63.5 +/- 4.2%) than bulls with a medium libido (n = 23). However, pregnancy rates achieved by bulls of either libido classification did not differ significantly. Individual components of the BSE as well as mean libido score were poorly correlated with pregnancy rates (r = -0.22 to 0.18). It was concluded that classification of bulls by mean libido score can aid in identifying groups of bulls that service more estrus synchronized females, whereas classification by BSE score aids in identifying groups of bulls that impregnate more females.     

Breeding soundness evaluation of extensively managed bulls in Costa Rica

This paper describes the results of single breeding soundness evaluations (BSE) in 898 Bos indicus, Bos taurus and B. indicus x B. taurus bulls, 1 to 12 yr old, extensively reared in different climatic regions of Costa Rica and representing approximately 2% of the total breeding bull population. Thirty-three percent (n = 296) of the bulls were classified as unsound for breeding owing to clinical problems (9.1%, n = 82), low scrotal circumference (SC) being the most common finding, followed by unsatisfactory sperm morphology (23.9%, n = 214). The prevalence of bulls unsound for breeding was lowest in Bos indicus (29%, P < 0.01), intermediate in B. taurus (41%), and highest in B. indicus x B. taurus (48%). The percentages of abnormal sperm heads, acrosomes and midpieces tended to be higher in the ejaculates of bulls with softer testicular consistency (P < 0.001), a long scrotum (P < 0.01) or a low SC (P < 0.05), and such bulls were more often classified as being unsound for breeding (P < 0.05). Frequencies of sperm abnormalities were higher in bulls < 2 yr of age than in older males (P < 0.01) and were highest in B. indicus x B. taurus bulls (P < 0.001). The results confirm differences between species in their adaptability to a tropical environment and support earlier evidence of an association between SC, testicular consistency and scrotal length clinical parameters, and testicular function in bulls.     

Resting behaviour of Belgian White-Blue and Friesian fattening bulls in a tie-stall barn

Standing and lying bouts of 11 fattening bulls were recorded continuously during two 1-week trials. There were 6 Friesian bulls and 5 double-muscled bulls from the Belgian White-Blue breed. At the start of Trial 1, the Friesian and Belgian White-Blue bulls averaged respectively. Trial 2 started 84 days later when the liveweight was about 100 kg more. The bulls were tied up in a stanchion barn. Standing up and lying down were recorded by an electrical device.The mean lying times per 24 h of the Friesian bulls were 16.52 h in Trial 1 and 16.13 h in Trial 2; the corresponding values for the Belgian White-Blue bulls were 15.77 and 16.82 h. Differences between breeds and between trials were not significant. The variability between the Belgian White-Blue bulls was larger than between the Friesians. The mean number of lying bouts per 24 h ranged from 12.31 to 16.97, the highest value being observed with the double-muscled animals in Trial 2.Resting behaviour was different between the day and the night. From 18.00 to 06.00 h, the lying time ranged from 9.75 to 10.89 h according to group; from 06.00 to 18.00 h, the corresponding values were 5.56 and 6.71 h.The repartition of lying bouts according to their length was not different between trials for the Friesian bulls. The proportions of lying bouts shorter than 15 min and longer than 1 h were on average 7.6 and 59.2%. For the Belgian White-Blue bulls, the repartition was different between trials: the proportions of lying bouts shorter than 15 min were 4.6 and 7.9% in Trials 1 and 2, respectively; those longer than 1 h were 60.6 and 43.6%. The proportions of lying times of long duration (>2 h) and standing times of short duration (<15 min) were higher for the Friesian than for the Belgian White-Blue bulls.     

Energy and protein requirements of Belgian Blue double-muscled bulls

Energy and protein requirements were determined for Belgian Blue double-muscled (BB dm) bulls based on the results of two feeding trials and a trial with serial slaughtering. The results of the serial slaughter experiment allowed calculation of chemical composition and energy content of the empty body, as well as protein and energy deposition at various live weights between 350 and 650 kg. Protein requirements were calculated based on the protein requirements for maintenance, the protein mass accreted and the efficiency of protein accretion. Efficiency of protein deposition (g protein accretion/g protein intake for accretion) was derived from the feeding experiments based on marginal protein levels; it decreased from 0.53 to 0.44 with increasing live weight. Energy requirements were also derived from the same database. Net energy for maintenance was estimated, with these animals that received an optimum energy/protein ratio, by subtracting the net energy retained from the net energy intake. Requirements were then determined by summation of the energy requirements for maintenance and the energy requirements for accretion. Conclusively, energy and protein requirements were determined for BB dm bulls for live weights from 350 to 650 kg and for different growth rates. As such, surpluses of energy and protein that BB dm animals require compared to other beef breeds, were quantified.     

Breeding soundness evaluations of Senepol bulls in the US Virgin Islands

The breeding soundness evaluation (BSE) was used to evaluate Senepol (Bos taurus) bulls (n = 495) on St. Croix over a 7-year period. Young, unproven bulls (10-26 months of age) and breeding bulls (16 months to 8.5 years) were tested prior to sale or use in breeding. Inbreeding coefficients were determined for a subset of bulls (n = 290). The percentage of bulls passing the BSE increased (P < 0.0001) with age. Bulls that passed had a higher percentage (P < 0.0001) of normal and motile sperm as well as a larger (P < 0.0001) scrotal circumference than bulls that failed. No bulls failed the BSE for physical soundness traits or other health reasons. The incidence of testicular hypoplasia was 2.5 and 3.3% and the incidence of cryptorchidism was 1.4 and 0.9% in 12- and 16-month-old bulls, respectively, with no occurrence in bulls >20 months. The proportion of all bulls that failed the BSE and received an Unsatisfactory rating for scrotal circumference or sperm motility decreased (P < 0.0001) from >90 to <25% with age. The proportion of all bulls that failed the BSE and received an Unsatisfactory rating for sperm morphology decreased (P < 0.0001) from 99 to 83.3% with age. The inbreeding coefficient was higher (P < 0.03) in bulls that failed the BSE than in those that passed (2.24 +/- 0.19% versus 1.40 +/- 0.32%, respectively). There was a tendency for bulls with testicular hypoplasia or cryptorchidism to have a higher (P = 0.09) inbreeding coefficient than bulls with normal testes (2.90 +/- 0.46% versus 2.13 +/- 0.11%, respectively). In conclusion, Senepol bulls raised under tropical conditions had a low probability of passing the BSE at young ages, but the passing rate increased with age. Older Senepol bulls were more likely to fail the BSE due to abnormal sperm morphology than due to inadequate testicular size or sperm motility. To prevent unnecessary culling, a BSE should not be performed on Senepol bulls <16 months old.     

Breeding soundness examination of Chianina, Marchigiana, and Romagnola yearling bulls in performance tests over a 10-year period

The objectives of the present study were (i) to establish the mean value of scrotal circumference (SC), sperm motility, concentration and morphology at 13+/-1 months of age for Chianina, Marchigiana, and Romagnola breeds and (ii) to assign Italian beef bulls at the end of a growth performance test to a potential breeder category by applying the guidelines of the Society for Theriogenology in 1993 (SFT93). Of 1,315 bulls, 869 were not given the breeding soundness examination for the following reasons: not passing the growth performance test (n=445), no training for semen collection (n=404), and presence of genital abnormalities (n=20). Testicular length and diameter and SC exhibited a logarithmic trend over time, with an R(2) value of 0.963, 0.979, and 0.978 (P<0.001), respectively. The SC of Romagnola (33.82+/-2.47 cm) was higher than those of Chianina (33.28+/-2.65 cm, P<0.001) and Marchigiana (33.05+/-2.20 cm, P<0.001). Sperm concentration in Romagnola (875.89+/-416.13x10(6)cells/mL) was higher than those in Chianina (751.63+/-444.45 x 10(6)cells/mL, P<0.05) and Marchigiana (862.57+/-421.87 x 10(6) cells/mL). Progressive sperm motility was 61.30+/-11.24%, 62.18+/-11.17%, and 58.48+/-14.40% in Romagnola, Marchigiana, and Chianina, respectively. Total spermatozoal abnormalities were higher in Chianina (23.35+/-15.41%). Sperm concentration was positively related to testicular length (P<0.01), diameter (P<0.001), and SC (P<0.001). Satisfactory breeders presented high sperm motility compared with deferred and unsatisfactory ones, whereas unsatisfactory breeders had a higher number of abnormal spermatozoa. By applying the SFT93 guidelines, we showed that 74.72%, 78.01%, and 80.16% of Chianina, Marchigiana, and Romagnola bulls, respectively, have been classified as satisfactory potential breeders.     

Breeding soundness and sex drive by breed and age in beef bulls used for natural mating

A total of 92 range beef bulls (Hereford = 60; Angus = 32) were given a breeding soundness examination (BSE) and two assessments for sex drive prior to their use in 23 breeding trials employing estrous synchronized females. Bulls were in three age groups: yearlings (n=29), two year olds (n=36), and three year olds and older (n=27). All yearling bulls were virgins, but the majority of the older bulls had previous mating experience. Angus bulls were superior (P<0.01) to Herefords in spermatozoal morphology and BSE score. Scrotal circumference increased with age beyond two years in Angus bulls but not in Herefords. Spermatozoal abnormalities generally decreased with age. BSE scores did not differ significantly among age groups. Apart from number of mounts, measures of sex drive did not differ with age or breed of bulls. This represents qualified justification for the current practice of using the same sex-drive assessment procedures for Bos taurus bulls of various ages and breeds.     

Rumen escape of methionine and lysine administered intraruminally to growing double-muscled Belgian Blue bulls

In many dietary conditions, methionine (Met) and lysine (Lys) are the most limiting amino acids (AA) for ruminants. The AA protected from ruminal fermentation are not commercially available, with the exception of Met which is not always economical, especially for meat production. This study measured ruminal escape of free Met and Lys supplemented intraruminally to fast growing bulls. Six double-muscled Belgian Blue bulls, fed a high concentrate diet and fitted with a rumen cannula, received free Met (40 g x d(-1)) and free Lys (60 g x d(-1)), individually or simultaneously, in a duplicated Latin square design. The mean ruminal escape of Met and Lys reached 37 and 45% respectively, and did not differ if administered separately or together. Plasma Lys and Met concentrations were increased by 504 and 126%, respectively. Substantial proportions of free AA escaped ruminal fermentation and were available for absorption from the small intestine when they were administered at physiologically high levels.     

Comparison of contractile characteristics of muscle from Holstein and double-muscled Belgian Blue foetuses.

The aim of the present study was to precise the origin of the particular muscle characteristics of double-muscled cattle by comparing muscle properties of Holstein and double-muscled Belgian Blue (BB) foetuses. Ten 100-day-old foetuses of each genotype were studied. The weight and length of foetuses and the length, weight and area of the Semitendinosus (ST) muscle were analysed. Contractile differentiation of the different fibre types was studied by immunohistochemistry using several monoclonal antibodies raised against different myosin heavy chain isoforms (MHC slow, fast, foetal) and by electrophoresis. Proliferation phase of myoblasts from each genotype was analysed in primary culture. On 100 days of foetal life, the foetuses of both genotypes did not show any significant differences in their weight and length. However, BB cattle already present muscle hypertrophy, which seems to originate from a higher myoblast proliferation observed in primary culture. The use of anti-MHC antibodies shows that ST muscle of BB contained a smaller proportion of primary fibres and a higher proportion of secondary fibres which will give principally fast fibres in adult muscle. Electrophoresis analysis confirms a lower proportion of slow MHC in ST of BB.     

Influence of season on characteristics of the ejaculate from bulls in an artificial insemination centre in Nigeria

The influence of season on the ejaculate characteristics of Zebu, Friesian and their crossbred bulls in an A.I. programme in Nigeria was investigated over a 2-year period.Ejaculate volume, sperm concentration, percent morphologically normal spermatozoa and percent live spermatozoa were significantly higher in the rainy season than in the dry season. Total spermatozoa per ejaculate averaged 3.32 × 10⁹ and 10.10 × 10⁹ for the dry and rainy seasons respectively. Corresponding proportions of total morphologically defective spermatozoa per ejaculate were 14.05% and 6.46%. Percent live spermatozoa were 82.34% and 84.61% while the corresponding sperm concentrations were 0.97 × 10⁹ rmand 1.74 × 10⁹ for the dry and rainy seasons respectively. All differences were statistically significant (P < 0.05).Ejaculate quality was better during the rainy season. Consequently semen collected and frozen during the rainy season may produce higher fertility rates in an A.I. programme.     

Relationship of seminal vesicle size and measures of libido in yearling beef bulls

Ninety-five yearling beef bulls were given routine Breeding Soundness Examinations, two libido tests and palpated rectally for internal genital disease and measurement of seminal vesicle size. Finger tips were premeasured, and then used as "glandometers". The bulls were examined at the end of a 140-day performance test. Sixteen lines of breeding were examined including 13 Hereford, 2 Angus and 1 Red Angus. Average age was 384 days and average weight was 961 lbs. Line and breed differences (P<.05) were observed for scrotal circumference, scrotal circumference score and second libido test. Similar differences were observed for SV length (P<.01), depth and volume both (P<.05). There were no significant correlations between seminal vesicle (SV) size and libido scores. There were, however, significant correlations between SV size and scrotal circumference (P<.05), BSE score (P<.01), body weight (P<.01), and semen morphology score (P<.05). Proximal droplets and midpiece abnormalities, respectively, were the most common spermatozoal abnormalities observed in semen from this group of bulls.     

Effects of using vasectomized bulls in artificial insemination practice on the reproductive efficiency of Italian buffalo cows

The effects of the presence or absence of vasectomized male buffaloes on the reproductive efficiency of buffalo cows (n = 396) undergoing artificial insemination (AI) was studied on six farms owned and operated by a single consortium. Lactating animals were separated into two groups of various sizes on each farm and kept under semi-range conditions. Vasectomized bulls were present in one group at a bull/empty-cow ratio of 1:30. No bulls were present in the other group. Reproductive efficiency between the two groups over a period of 3.5 months was compared and evaluated on the basis of: 1) the number of spontaneous overt estruses associated with either feeble or intense signs of estrous behaviour; 2) the number of functional estrous cycles, i.e. estrous cycles with luteal phases defined as normal, based on specified progesterone concentrations in milk or blood plasma 8–10 days after estrus; 3) the number of consecutive functional estrous cycles in cases of induced estrus; and 4) pregnancy rate.Groups with bulls present demonstrated a significantly higher reproductive efficiency than groups without them. There was a higher incidence of spontaneous estrus (92 versus 69%; P < 0.01); spontaneous estrus of high intensity (62.2 versus 31.1%; P < 0.01); and higher incidence of functional estrous cycles following both spontaneous (65.8 versus 57.1%) and induced (77.0 versus 59.5%; P < 0.05) estrus. Exposure to vasectomised bulls also increased the incidence of consecutive functional estrous cycles (90.5 versus 68.1%; P < 0.01), and the pregnancy rate in cows inseminated at spontaneous (42.5 versus 18.9%; P < 0.01) or induced (51.1 versus 33.3%; P < 0.05) estrus. Overall pregnancy rate did not differ significantly between cows inseminated at induced or spontaneous estrus, although in the absence of bulls, pregnancy rate per AI was higher in cows inseminated at induced than at spontaneous estrus (33.3 versus 18.9%).     

Scrotal insulation and its relationship to abnormal morphology, chromatin protamination and nuclear shape of spermatozoa in Holstein-Friesian and Belgian Blue bulls

The objectives of this study were to identify the stages of spermatogenesis susceptible to elevated testicular temperature in terms of sperm motility, viability, morphology, chromatin protamination and nuclear shape. The latter two valuable parameters are not included in routine semen analysis. Scrotal insulation (SI) was applied for 48 h in 2 Holstein-Friesian (HF) and 2 Belgian Blue (BB) bulls and semen was collected at 7 d intervals along with semen collection of a non-insulated bull of each breed. Semen samples were frozen and assigned to 4 groups: period 1 (preinsulation) = −7 d and 0 d, where 0 d = initiation of SI after semen collection; period 2 = 7 d (sperm presumed in the epididymis during SI); period 3 = 14 d to 42 d (cells presumed at spermiogenesis and meiosis stages during SI); period 4 = 49 d to 63 d (cells presumed at spermatocytogenesis stage during SI). The percentages of progressively motile and viable spermatozoa as assessed by computer-assisted sperm analysis (CASA) and fluorescence microscopy, respectively were decreased whereas abnormal sperm heads, nuclear vacuoles and tail defects were increased at period 3 (P < 0.05) compared to period 1, 2 or 4 in SI bulls of both HF and BB breeds. Protamine deficient spermatozoa as observed by chromomycin A₃ (CMA₃) staining were more present (P < 0.05) at period 2 and 3 in both breeds compared to period 1 or 4. Sperm nuclear shape as determined by Fourier harmonic amplitude (FHA) was most affected by heat stress during period 3 (P < 0.01) and a higher response was observed in BB bulls than HF bulls. In conclusion, sperm cells at the spermiogenic and meiotic stages of development are more susceptible to heat stress. The lack of chromatin protamination is the most pertinent result of heat stress, together with subtle changes in sperm head shape, which can be detected by FHA but not by conventional semen analysis.     

The relationship between breeding soundness evaluation and fertility of beef bulls under group mating at pasture

The relationships between natural service fertility of beef bulls and the components of breeding soundness evaluation, age, preweaning average daily gain, yearling weight and scores of two libido tests were studied in two seedstock herds. In one of the herds (YBH), 15 yearling bulls were rotated during six-week breeding season so that each group of five bulls served the cows for a period of one week and rested for two weeks before the next exposure. Five older bulls (one 3-year old and four 2-year old) were assigned to the other herd (MBH) during the entire breeding season (six weeks). The progeny of each bull were identified by blood typing.Calf crop was 6.4% higher (P=0.14) in the MBH compared with that in the YBH. There were large differences in fertility between the bulls in the MBH. The 3-year old bull sired 40.9% of the calves, presumably due to his high social dominance order. The third group of yearling bulls, which served the herd during the third and sixth weeks of breeding, sired the highest number of calves (49.4%) compared with the other two groups (28.4% and 22.2%). In each of the groups one and two of the yearling bulls, one bull did not produce any progeny, while another one sired 44% of the calves. The correlation coefficients between fertility of the bulls and the traits used to predict their fertilizing capacity were generally small and inconsistent in different groups, when the effect of age in the mixed age group was removed. The correlation coefficients of bull fertility with scrotal circumference and reproductive system score were higher and more consistent in different groups as compared with the other traits studied.     

The effect of continuous light on prolactin secretion in prepubertal Holstein bulls

Effects of 16 (16 light:8 dark) and 8 (8L:16D) h of daily light were compared with continuous light (24L:0D) exposure on prolactin (PRL) concentrations in serum of prepubertal bulls. Concentrations of PRL in serum were 2 to 3 fold greater in bulls exposed to 24L:0D or 16L:8D as compared with 8L:16D. However, PRL concentrations attained a maximum approximately 3 weeks later in calves exposed to 24L:0D than in calves given 16L:8D. Continuous low intensity (11 to 16 lux) lighting supplemented with 16 or 8 h of high intensity (449 to 618 lux) light per day increased PRL concentrations in serum of prepubertal bulls 1.5 to 2.5 fold relative to 8L:16D (470 lux). We found that relative to 8L:16D, 1) photoperiods of 16 or 24 h of light per day increased serum concentrations of PRL in prepubertal bulls; however, the time required to achieve maximum PRL concentrations was longer in animals exposed to 24L:0D, 2) continuous low intensity lighting supplemented with 16 or 8 h of high intensity daily light also increased concentrations of PRL in serum.     

Effect of diets rich in N-3 polyunsatured fatty acids on muscle lipids and fatty acids in Belgian Blue double-muscled young bulls

The present study was aimed at investigating the effect of duration and time of feeding n-3 fatty acids on the fatty acid composition of intramuscular fat and adipose tissue of bulls at slaughter. Four groups of bulls were given during three periods different diets, mainly differing in the presence of linseed as the predominant n-3 fatty acid source in the concentrate either or not in combination with grass (silage) as the roughage. The results show that the fatty acid composition of the feed during the earlier periods of life of the animal were important and influenced the final intramuscular fatty acid composition. Feeding n-3 PUFA during the phases before the finishing diet increased the long chain n-3 PUFA (C20:5n-3, C22:5n-3 and C22:6n-3) compared to animals which were fed only a C 18:3n-3 rich concentrate in the finishing period. The cis-9,trans-11CLA content was increased by feeding linseed in the fattening period and was mainly deposited in the triacylglycerol fraction of the intramuscular fat.     

The effect of timing of the induction of ovulation on embryo production in superstimulated lactating Holstein cows undergoing fixed-time artificial insemination

Two experiments evaluated the effects of timing of the induction of ovulation in superstimulated lactating Holstein donor cows that were fixed-time artificially inseminated. Secondary objectives were to evaluate the effects of the timing of progesterone (P4) device removal (Experiment 1) or the addition of a second norgestomet implant (Experiment 2) during superstimulation. In Experiment 1, 12 cows were allocated to one of four treatment groups with the timing of P4 device removal (24 or 36 h) and pLH treatment (48 or 60 h), after the first PGF as main factors, in a Latin Square (cross-over) design. There was an interaction (P = 0.03) between time of P4 device removal and time of pLH treatment. Mean (± SEM) numbers of transferable embryos were higher when the P4 device was removed at 36 h and pLH was administered at 60 h after the first PGF (P36LH60 =6.3 ± 1.4) compared to other treatments (P24LH60 =3.7 ± 1.1; P24LH48 =2.4 ± 0.8; or P36LH48 =2.2 ± 0.7). In Experiment 2, 40 cows were randomly allocated into one of four treatments with the number of norgestomet implants (one or two) and the time of induction of ovulation with GnRH relative to the first PGF (48 vs. 60 h) as main effects. The mean number of transferable embryos was higher (P = 0.02) when GnRH was administered at 60 h (4.2 ± 1.3) compared to at 48 h (2.7 ± 0.8), and the number of freezable embryos was increased (P = 0.01) in cows receiving two (3.0 ± 1.0) rather than one norgestomet implant (1.5 ± 0.5). In summary, embryo production in lactating Holstein cows was increased when the ovulatory stimulus (pLH or GnRH) was given 60 h after the first PGF, particularly when the P4 device was removed 36 h after the first PGF and when two norgestomet ear implants were used during the superstimulation protocol.