Conception of Jersey cattle in Turkey

To determine the effects of insemination season (IS; dry: May through October and rainy: November through April), lactation number (LN; heifers, primiparous or multiparous) and their interaction on non-return rate (NRR), conception rate (CR) to first-service and pregnancy loss (PL) of Jersey cattle in Turkey, over 1468 lactation records from 510 Jersey dairy cows were used. There was an interaction between LN × IS on NRR, CR to first-service (p < 0.01) and PL (p < 0.05). The NRR and CR to first-service of heifers inseminated during dry season and of primiparous inseminated during rainy season were higher (p < 0.01) than that of multiparous inseminated during both season. The NRR and CR of heifers and primiparous were higher (p < 0.05) than that of multiparous cows. The insemination of heifers during rainy season and of primiparous and multiparous during dry season increased (p < 0.01) the PL compared to the inseminations of heifers during dry season and of primiparous during rainy season. The PL was lower (p < 0.05) in primiparous than multiparous cows. The results demonstrate that the heifers have high fertility than the lactating, especially multiparous and that IS appeared to have a measurable impact on traits relating to conception of Jersey cattle in the each LN.     

Effects of a novel missense polymorphism within the SIGLEC5 gene on fertility traits in Holstein‐Friesian cattle

The aim of the study was to find functional polymorphism within two exons of the SIGLEC5 (sialic acid‐binding Ig‐like lectin‐5) gene and to examine its effects on the production and fertility traits of cows and bulls. Two hundred seventytwo Holstein‐Friesian cows and 574 bulls were included in the study. Novel missense polymorphism (A > G) within exon 3 causing substitution of amino acid arginine by glutamate in position 260 of SIGLEC5 protein (R260Q) was identified by sequencing and digestion by restriction enzyme Msp I. Basic production and fertility traits of cows and estimated breeding values (EBV) of bulls were analysed. The study demonstrated a significant association of SIGLEC5 R260Q polymorphism with days open and calving interval in cows as well as with breeding value for calving interval in bulls. An opposite effect of SIGLEC5 alleles for production and fertility traits was observed: the allele G increased the breeding value for the protein yield, while the allele A increased the breeding value for the calving interval. The current study suggests the involvement of SIGLEC5 R260Q polymorphism in biological processes related to fertility traits. This finding can be applied as a biomarker for a genetic improvement programme in Holstein‐Friesian cattle.     

Effects of supplementary concentrate level in winter, and subsequent finishing on pasture or indoors, on performance and carcass traits of Holstein–Friesian, Aberdeen Angus × Holstein–Friesian and Belgian Blue × Holstein–Friesian steers

Pure bred Holstein–Friesian (FR) and beef breed × FR male calves are used for beef production in Ireland. Beef breeds used for crossbreeding on FR cows include Aberdeen Angus (AA) and Belgian Blue (BB) which represent extremes in terms of maturity. The objective of this study was to compare spring-born steers of FR, AA and BB breed types, offered two feeding levels in their second winter, and subsequently finished on pasture or on a high concentrate diet indoors. Seventy-two steers (24 per breed type) were managed together to the end of their second grazing season. They were then blocked on weight within breed type and assigned to a 3 (FR, AA and BB breed types) × 2 (winter feeding levels) × 2 (finishing systems) factorial experiment. The two winter feeding levels were grass silage ad libitum plus mean daily concentrate levels of 0.91 (L) or 4.0 (H) kg dry matter for 113 days. The two finishing systems were pasture or concentrates ad libitum for a mean period of 94 days. Mean slaughter and carcass weights for FR, AA and BB were 634, 644 and 642 (s.e. 8.1), and 313, 326 and 340 (s.e. 4.7) kg, respectively. Other than bone proportion which was lower for AA, there were few differences in ribs joint composition or in m. longissimus chemical composition between FR and AA. BB had less fat and more muscle in the ribs joint, and more moisture and protein, and less lipid in m. longissimus than both FR and AA. Compared with L, the H winter feeding level increased slaughter weight and carcass weight by 24 and 15 kg, respectively. Indoor finished animals were 63 kg live weight and 39 kg carcass weight heavier than those finished at pasture. They also had more fat and less muscle and bone in the ribs joint and more lipid and less moisture in m. longissimus. It is concluded that except for BB finished at pasture all carcasses were commercially acceptable. Despite the excellent finishing performance on concentrates, this system is not profitable at current concentrate and beef prices.     

Economic weights of production and functional traits for Holstein‐Friesian cattle in Hungary

A bio‐economic model was used to estimate economic values of 15 milk production, functional, growth and carcass traits for Hungarian Holstein‐Friesian cattle. The calculations were carried out for the situation in Hungary from 2000 to 2007, assuming no production quotas. The marginal economic values were defined as partial derivatives of the profit function with respect to each trait in a production system with dairy cow herds and with sales of surplus male calves. The economic weights for maternal and direct components of traits were calculated multiplying the marginal economic values by the number of discounted expression summed over a 25‐year investment period for 2‐year‐old bulls (candidates for selection). The standardized economic weight (economic weight × genetic standard deviation) of the trait or trait component expressed as percentage of the sum of the standardized economic weights for all traits and trait components represented the relative economic importance of this trait or trait component. The highest relative economic importance was obtained for milk yield (25%), followed by productive lifetime of cows (23%), protein yield and the direct component of a cow’s total conception rate (9% each), the maternal effect of the total conception rate of cows and the somatic cell score (approximately 7% each), fat yield (5%) and mature weight of cows and daily gain in rearing of calves (approximately 4% each). Other functional traits (clinical mastitis incidence, calving difficulty score, total conception rate of heifers and calf mortality) reached a relative economic importance between 0.5% and 2%. Birth weight and dressing percentage were least important (<0.5%). Based on these results, the inclusion of productive lifetime and cow fertility in the breeding programme for Holstein‐Friesian cattle in Hungary is advisable.     

Effect of strain of Holstein–Friesian and feed system on calving performance, blood parameters and overall survival

The objective of the present study was to quantify the effect of strain of Holstein–Friesian and pasture-based feeding system on calving performance, blood parameters and overall survival within a seasonal calving milk production system. The three strains of Holstein–Friesian compared were high production North American (HP), selected entirely for milk production, high durability North American (HD), selected based on milk production, fertility and muscularity traits, and New Zealand (NZ) selected from a seasonal calving pasture-based system. The three feed systems compared were a high grass allowance feed system typical of spring calving herds in Ireland (MP; control); an increased stocking rate system (HS) and an increased concentrate supplementation system (HC). Data comprised up to 585 lactations on 240 cows. Data were analysed using linear mixed models, generalised estimating equations and survival analysis. Strain of Holstein–Friesian had no significant effect on calving difficulty or rate of stillbirths while the effect of feed system on calving difficulty and rate of stillbirths approached significance. Strain of Holstein–Friesian had no significant effect on plasma metabolite or hormone concentrations around parturition, with the exception of urea concentration. At the beginning of the breeding season the NZ strain had lower plasma concentrations of NEFA (0.20 mmol/l) and higher IGF-I (86.8 ng/ml) than the HD (0.24 mmol/l and 66.9 ng/ml, respectively) and HP (0.26 mmol/l and 64.0 ng/ml, respectively) strains. The higher IGF-I concentration of the NZ strain was maintained during the breeding season. The NZ and HD strains survived longer than the HP strain with median survival days post-first calving of 1372, 1367 and 1033 respectively, while feed system had no significant effect on overall survival rate over the study period.     

Effect of wheat processing on rumen characteristics and rumen parameters in Holstein‐Friesian calves

In this experiment, effect of wheat processing on rumen conditions and development were investigated. Fifty‐six neonatal Holstein‐Friesian calves (22 male and 34 female) were fed calf starters and post‐weaning diets containing 35 (pre‐weaning) and 21.90% (post‐weaning) popped wheat (PW), steam‐flaked wheat (SFW), dry‐rolled wheat (DRW) or ground wheat (GW) till 12 weeks of age. Calves were weaned at the end of 9th week, and a post‐weaning‐specific starter diets were fed for 1 month. Rumen liquor was analysed in days 30, 60 and 90 of the experiment to determine volatile fatty acids (VFA), pH and ammonia nitrogen concentrations. Twelve male calves (three calves/treatment) were slaughtered, and digestive tract was emptied. Forestomach empty weight and rumen parameters were assessed. Results indicated that calves received PW had the highest total VFA, acetate, propionate, butyrate, ammonia nitrogen, rumen wall thickness, papilla width and density. Calves fed DRW experienced the lowest rumen pH throughout the experiment probably because high proportion of fine particles in GW. Calves consuming PW apparently had more functional rumen in comparison with other groups.     

Cooling and feeding strategies to reduce heat load of grain-fed beef cattle in intensive housing

Six Murray Grey × Hereford yearling steers were used to determine the effect of two cooling treatments (ENV) (day cooled (0600–1400) or night cooled (1400–2200), and two dietary treatments (DIET) – control (CON) no added fat or added fat (FAT) – on rectal temperature, respiration rate and dry matter intake (DMI). Cattle were exposed to 2 d of thermoneutral conditions followed by four hot days in a controlled climate facility. This was replicated 6 times. Steers were given a 10 d rest in outside pens between each replication. Sprinklers (2.84 L min^− 1; 5 min on, 20 min off) and fans (continuous; 2 m s^− 1) were used when ambient temperature (T_A) ≥ 28 °C. Rectal temperature (5 min intervals) and respiration rate (hourly) were measured for 12 × 24 h periods on hot days (2 per replication). Individual DMI over two time periods (PER) (period 1; 0600–1500, and period 2; 1500–0600) and daily metabolisable energy (ME) intakes were also recorded. Steers fed FAT had greater (P < 0.05) DMI then the CON steers during day cooling. However, there were no DIET or PER differences for DMI during night cooling. DMI of FAT and CON fed steers during night cooling was similar to the DMI of the FAT fed steers during day cooling. Overall DMI was greater during night cooling (DMI from both diets pooled). There were PER differences for DMI, with more (P < 0.05) feed consumed during period 2 irrespective of ENV or DIET. ME intake was 22.9% greater (P < 0.05) for the FAT fed steers during day cooling then for the CON fed steers. There were no DIET effects on ME intake during night cooling. DIET had no effect (P > 0.05) on respiration rate however differences were seen for rectal temperature. Mean rectal temperature for the FAT steers was lower (P < 0.05) than the mean of the CON steers, however there were no within ENV differences. Day cooled cattle had a higher (P < 0.05) respiration rates (71.8 breaths/min; bpm) than the night cooled steers (65.3 bpm). There were no differences for rectal temperature. However, day cooled steers had lower (P < 0.05) rectal temperature and respiration rate than the night cooled steers during the day — which corresponded with the day cooling period. Night cooling appears to be beneficial in lowering mean rectal temperature and respiration rate, and in maintaining DMI. There is no suggestion that feeding fat will replace the need for supplementary measures to alleviate heat exposure of confined cattle. However feeding fat may be worthwhile in maintenance DMI when combined with strategies involving day cooling.     

Influence of environmental temperature on the physiological, endocrine, and immune responses in livestock exposed to a provocative immune challenge

Although livestock experience many stressors throughout their life, one of the most commonly experienced, and most difficult to control, is stress caused by fluctuations in environmental temperatures that extend beyond the thermoneutral (TN) zone for an animal. In swine, cold stress has long been recognized as a main cause of neonatal morbidity and mortality. A possible explanation for this increased morbidity and mortality may be related to their inability to generate a febrile response. Previously, we reported that the acute phase immune response, including the generation of fever, after exposure to lipopolysaccharide (LPS; Escherichia coli O111: B4; Sigma-Aldrich, St Louis, MO, USA) is substantially altered in neonatal pigs maintained in a cold environment (ie, 18°C). Neonatal pigs that were maintained in a cold environment and administered LPS experienced a period of hypothermia coupled with altered endocrine and proinflammatory cytokine responses that could prove detrimental. In cattle, we previously reported differences in the acute phase immune response of two diverse breeds of Bos taurus cattle (Angus and Romosinuano) when maintained under TN conditions and exposed to LPS. More recently we have reported that differences in the stress and immune responses of Angus and Romosinuano heifers varies, depending on whether the cattle were housed at either TN or heat stress air temperatures. Our data clearly show that even intermittent periods of heat stress similar to that experienced in production environments can have significant effects on the stress and innate immune responses of cattle. Understanding the effect of thermal stress on livestock is critical to developing and implementing alternative management practices to improve their overall health and well-being.     

Comparison of heritabilities of dairy traits in Australian Holstein‐Friesian cattle from genomic and pedigree data and implications for genomic evaluations

The reliability of genomic evaluations depends on the proportion of genetic variation explained by the DNA markers. In this study, we have estimated the proportion of variance in daughter trait deviations (DTDs) of dairy bulls explained by 45 993 genome wide single‐nucleotide poly‐ morphism (SNP) markers for 29 traits in Australian Holstein‐Friesian dairy cattle. We compare these proportions to the proportion of variance in DTDs explained by the additive relationship matrix derived from the pedigree, as well as the sum of variance explained by both pedigree and marker information when these were fitted simultaneously. The propor‐ tion of genetic variance in DTDs relative to the total genetic variance (the total genetic variance explained by the genomic relationships and pedigree relationships when both were fitted simultaneously) varied from 32% for fertility to approximately 80% for milk yield traits. When fitting genomic and pedigree relationships simultaneously, the variance unexplained (i.e. the residual variance) in DTDs of the total variance for most traits was reduced compared to fitting either individually, suggesting that there is not complete overlap between the effects. The proportion of genetic variance accounted by the genomic relationships can be used to modify the blending equations used to calculate genomic estimated breeding value (GEBV) from direct genomic breeding value (DGV) and parent average. Our results, from a validation population of young dairy bulls with DTD, suggest that this modification can improve the reliability of GEBV by up to 5%.     

Effect of health status on fattening performance in young crossbred polish Holstein‐Friesian × Limousin Bulls and steers

The aim of this study was to determine the effect of disease incidence on selected parameters of cattle fattening performance and carcass quality, and the fatty acid profile of beef. The experimental materials comprised 16 bulls and 16 steers, Polish Holstein‐Friesian × Limousin crossbreeds (including 10 healthy and six treated animals of each category). At 5 weeks of age, bloodless castration was carried out using a rubber elastrator. The calves were fed milk replacer provided in automatic feeding stations. Until 540 days of age, the animals were fattened in an Animal Research Laboratory equipped with the Roughage Intake Control (RIC) system (Insentec, the Netherlands). In comparison with healthy (untreated) bulls and steers, sick (treated) animals had lower average body weight at 180 days of age, by 37 kg (P ≤ 0.05) and lower average final body weight at 540 days of age, by 56 kg (P ≤ 0.05). Sick animals were characterized by lower feed intake and worse feed efficiency (not statistically significant differences). Hot carcass weight reached 318 kg in healthy animals and 258 kg in treated bulls (P ≤ 0.05). In treated steers, the percentage of lean meat and bones in the three‐rib section was higher and the percentage of fat was lower, compared with their healthy counterparts (P ≤ 0.01). There was a category × health status interaction for carcass tissue composition. There were no significant influences of type of sickness on analyzed traits. In comparison with healthy steers, intramuscular fat of Musculus longissimus dorsi (MLD) from treated steers had significantly (P ≤ 0.05) higher concentrations of polyunsaturated fatty acids (n‐6 and n‐3) and a lower content of conjugated linoleic acid.     

宁夏银川地区哺乳期犊牛舍环境因子监测

为研究犊牛舍环境的季节性变化,选取宁夏银川地区有代表性建筑类型的犊牛舍,对四季舍内的环境温度、相对湿度、风速以及二氧化碳、氨气的浓度进行测定。结果显示,犊牛舍内温度范围为-25.6～42.3℃,舍内平均湿度为7.1%～90.3%,舍内风速范围为0～6.77 m/s,氨气浓度范围为0～1.9 mg/m3,二氧化碳浓度范围为182～942 mg/m3;12个月中犊牛出现中度热应激累计34 d,轻度热应激累计55 d;7月20日犊牛舍24 h均处于热应激状态,其中9 h处于中度热应激状态,15 h处于轻度热应激状态;12个月中犊牛舍二氧化碳超标天数为18 d;冬季平均温度为-12℃,犊牛处于不利于生长的冷应激状态。研究表明,宁夏银川地区哺乳期犊牛夏季热应激强度大,冬季冷应激较为普遍,舍内风速过大,二氧化碳浓度超标。建议牛场考虑夏季增加防暑减温措施,冬季增加保暖措施,加强舍内通风换气,以减少有害气体产生,合理调配日粮配方,提高犊牛生产性能。     

Mortality and commercial off-take rates in adult traditional cattle of Zambia

A cohort study was conducted in the livestock-wildlife interface areas of Zambia to determine cattle mortality and commercial off-take rates among adult cattle as well as factors influencing them. A total of 416 animals from 43 herds were followed up for one year and animals were individually identified and their fate was indicated as sold, slaughtered, dead or present as appropriate. The overall mortality incidence risk was estimated at 7.5%. Cattle in Kazungula were at a greater risk of dying compared to those in Blue Lagoon and Lochnivar. Annual off-take was estimated at 13.7% (8.1–19.3%), unadjusted values, and 16.4% (8.1–24.5%) after adjusting for sampling fraction in primary sampling units (herds) and area stratification. Area variations were observed with Kazungula recording the highest in both instances, which was attributed to a contagious bovine pleural pneumonia (CBPP) outbreak. Herd size and gender were observed to influence cattle mortality rates. Cattle in the middle-sized herds (50–150 cattle) recorded high mortality rates (OR = 3.91) compared to smaller herds (10–50) and so were females compared to males (OR = 4.16). The logistic regression model showed that cattle death was influenced by managerial factors and that off-take rates tend to increase in the face of disease outbreaks.     

Association Between ETFA Genotype and Activity of Superoxide Dismutase,Catalase and Glutathione Peroxidase in Cryopreserved Sperm of Holstein–Friesian Bulls

The aim of this study was to determine whether C/T missense mutation within the ETFA gene is associated with sperm antioxidant enzymatic activity. One hundred and twenty Holstein–Friesian bulls were genotyped by the PCR‐RFLP technique (MwoI). Commercial straws of frozen‐thawed semen were used to evaluate the activity of three antioxidant enzymes: superoxide dismutase, catalase and glutathione peroxidase. Among all bulls investigated, genotype CT was the most frequent (44.2%), in comparison with CC (42.5%) and TT (13.3%). Significant differences in glutathione peroxidase activity were observed between homozygous individuals (CC vs TT) with heterozygous CT having intermediate values. Dismutase activity was significantly associated with ETFA genotype, although only bulls with the CT genotype were significantly different from bulls carrying the CC genotype. The activity of catalase showed a similar trend (but was not statistically significant). In conclusion, we found that bulls with the ETFA TT genotype produce sperm with the highest glutathione peroxidase activity and can therefore be more efficiently protected from reactive oxygen. The mechanism of this interaction needs to be elucidated in future research.     

Hydatidosis of slaughtered cattle in Wolaita Sodo Abattoir,southern Ethiopia

The study was carried out from July 2007 to June 2008 in Wolaita Sodo Abattoir to assess the status of hydatidosis in cattle. Routine meat inspection, hydatid cyst count and characterization were conducted. Out of 400 cattle slaughtered in Wolaita Sodo Abattoir 64 (16%) animals were found harboring hydatid cysts. Thorough meat inspection in the abattoir revealed that 74 visceral organ were found harboring one or more hydatid cysts. The infection of the lung, liver, spleen and kidney were found to be 45.94% 45.94%, 6.75% and 1.35% respectively. From the total of 283 hydatid cysts counted 153(54.06%), 17(6.00%), 5(1.76%), 108(38.16%) were found to be small, medium, large and calcified cysts respectively and 170(60.28%), 5(1.76%) and 108(38.16%) were sterile, fertile and calcified cysts respectively. The rate of cyst calcification was higher in the liver than in the lung while fertility rate was higher among the cysts of the lung. Hydatid cyst viability rate of 40% was observed.     

Effect of cereal-based concentrates on productivity of Holstein–Friesian cows grazing short-rotation ryegrass (Lolium multiflorum) or kikuyu (Pennesitum clandestinum) pastures

In this study, the effect of increasing the proportion of concentrate in the diet, on efficiency of feed utilisation, was determined when Holstein–Friesian cows grazed short-rotation ryegrass (Lolium multiflorum) or kikuyu (Pennisetum clandestinum) pastures. The concentrates were energy-dense dairy pellets fed twice-a-day at milking and the roughage component was lucerne hay and the pasture.When cows grazed ryegrass, there was no effect on animal performance as the proportion of concentrate in the diet increased from 0.23 to 0.35 (4.75 to 7.50 kg concentrate/cow/day). The substitution rate of concentrates for pasture for the first 1.57 kg concentrate/cow/day fed was 0.58 but rose to 1.18 for the next 1.28 kg concentrate/cow/day.When cows grazed kikuyu, there was also no effect of increasing the proportion of concentrate in the diet on total dry matter intake (DMI) or milk production. However, there was a substantial increase in the in vivo digestibility of whole diet, pasture and acid detergent fibre (ADF) was observed when the proportion of concentrate in the diet increased from 0.08 to 0.25. However, there was a marked decline in pasture digestibility (72% to 64%), and more so in ADF digestibility (61.3% to 48.4%), as the proportion of concentrate in the diet increased further to 0.29 (5.52 kg/cow/day). The intake of kikuyu, when determined by difference between pre- and post-grazing pasture mass, was substantially underestimated compared to the use of the n-alkane technique, and this discrepancy increased as the pasture on offer increased.On both pasture types, the neutral detergent fibre intake, as a % of bodyweight varying from 1.6% to 2.2% for kikuyu and 1.5% to 1.6% for ryegrass was far above the values claimed of 1.2% to restrict intake.The results of this study highlight the limits to the amount of concentrate that can be fed on a typical Australian dairy farm where concentrates can only be fed twice-a-day at milking. The results also provide a more appropriate benchmark for fibre limitation in the ration when cows graze pasture, particularly poorer quality tropical grasses, and this value is well above that found in more intense feeding situations.     

Effect of Orally Administered Cisapride,Bethanechol, and Erythromycin on the Apparent Efficiency of Colostral IgG Absorption in Neonatal Holstein‐Friesian Calves

Objective

To evaluate the effect of orally administered cisapride, bethanechol, and erythromycin on the absorption of colostral IgG in dairy calves.

Animals

Twenty‐four healthy neonatal Holstein‐Friesian calves.

Procedures

Calves were randomly assigned to one of the following treatments: 0.9% NaCl solution (2 mL, PO; negative control); erythromycin lactobionate (20 mg/kg BW, PO; anticipated to be a positive control); cisapride (0.5 mg/kg BW, PO); bethanechol chloride (0.5 mg/kg BW, PO). Calves were fed 3 L of pooled bovine colostrum containing acetaminophen (50 mg/kg) by suckling and oroesophageal intubation 30 minutes after each treatment was administered. Jugular venous blood samples were obtained periodically after the start of feeding and plasma total IgG, protein, acetaminophen, and glucose concentrations determined. Abomasal emptying rate was assessed by the time to maximal plasma acetaminophen concentration.

Results

Oral administration of cisapride facilitated the absorption of colostral IgG and protein. The effect of cisapride on abomasal emptying rate could not be evaluated because cisapride appeared to interfere with acetaminophen metabolism. Based on the total IgG and total protein concentration‐time relationships, the beneficial effects of cisapride appeared to occur early after oral administration and were transient.

Conclusions and Clinical Importance

Additional studies appear indicated to characterize the effect of cisapride dose on the magnitude and duration of its effect on facilitating the absorption of colostral IgG and protein. Identification of a nonantimicrobial method for increasing abomasal emptying rate, such as cisapride, will potentially provide a practical and effective method for facilitating transfer of passive immunity in colostrum‐fed dairy calves.     

不同时期断奶对牦母牛繁殖性能的影响

对178头牦母牛分别在8月26日(Ⅰ组)和10月6日(Ⅱ)进行犊牛断奶。Ⅰ组发情率为99%,繁殖率89%;Ⅱ组发情率28%,繁殖率33%。Ⅰ组比Ⅱ组的发情率和产犊率分别提高了66%和64%。群体受胎率提高了9.34%。对断奶后的母牛和犊牛进行人工补饲,母牛的膘情和犊牛的生长发育都良好。     

Relationship between haemoglobin types and productivity of Thai indigenous and Simmental × Brahman crossbred cattle

The relationship between the haemoglobin (Hb) type and reproduction and body weight was estimated in two different cattle breeds including 59 Thai indigenous and 51 Simmental × Brahman crossbred cows. Haemoglobin type was measured using cellulose acetate electrophoresis. Five haemoglobin types were present in indigenous cattle: HbAA (35.59%), HbAB (28.81%), HbAC (20.34%), HbBB (11.6%) and HbBC (3.39%). In the Simmental × Brahman crossbred cattle, three haemoglobin types, 50.98% HbAA, 45.10% HbAB and 3.92% HbBB, were present. The results revealed that Thai indigenous cows with HbAB type were heavier at birth, however, the best growth performance was recorded in HbAC animals. In contrast, calves carrying HbBB type were the lightest animals at birth and were the youngest group at first calving. This group of Thai indigenous cows was more than 4 months younger at first calving than the heifers with HbAA type. Simmental × Brahman crossbred cows with HbAA type were significantly (P < 0.05) heavier than the animals with HbAB type at birth as well as on days 200, 400 and 600 of age. Whereas, the animals with HbAB type gave birth to their first calf at a significantly (P < 0.05) younger age than those with HbAA type.     

三种抗牛运输应激技术的效果比较

本研究比较了3种抗应激处理措施防控肉牛运输应激的效果。74头试验牛分4组,分别在运输前用牛支原体弱毒疫苗滴鼻、肌内注射泰乐菌素或饲料中添加泰妙菌素,并设不做任何抗应激处理的对照。分别对试验牛起运前及运达后体温、血细胞数目、血清中酶含量、牛支原体抗体水平、生长速度、发病率、死亡率及治疗成本进行比较。结果显示,起运前及运达后试验牛体温、血细胞数及牛支原体抗体水平未见明显差异;泰乐菌素肌注组试验牛发病率、死亡率显著低于对照组（P〈0．01）;对照组试验牛治疗成本为抗应激处理组治疗成本的15．9倍。结果表明,运输前进行抗应激处理有利于降低肉牛运输应激,起运前肌注泰乐菌素抗运输应激效果最好。     

Effect of narrow sperm head shape on fertility in cattle

Seven experiments were done in feedlot heifers to determine the importance of various degrees of narrowness of the sperm head on fertility in feedlot heifers. Frozen semen used in these experiments was selected to be normal in all respects except for very high numbers of a single specific type of sperm head aberration. Semen with the sperm aberration in question and control semen were selected to be as similar as possible in dose and postthaw viability so that differences in fertility would be attributable to the morphological variant under study. Fertilization rates were determined by collecting embryos from the reproductive tracts of superovulated heifers which had been slaughtered seven days after insemination. Pregnancy rates and rates of embryonic loss were studied in estrus-synchronized heifers by repeated transrectal ultrasound examinations from day 22 to day 55 after insemination. Reproductive tracts were collected and examined after slaughter at 60 days postinsemination.

The combined results of these experiments show that a moderate degree of sperm head narrowness, in the absence of other seminal signs of a disturbance of spermatogenesis, is not detrimental to fertility. However, extreme narrowness of the postacrosomal region of the sperm head of most spermatozoa, as was found in two bulls without other seminal signs of a disturbance of spermatogenesis, resulted in significantly reduced fertility. The data suggest that, although a decision between normal and abnormal sperm morphology may contain a degree of subjectivity, of the defects studied only sperm with extreme narrowness of the post-acrosomal region are likely to reduce fertility.