Relationships of neonatal plasma oxytocin with the behavioral characteristics of cattle introduced into a novel environment

To examine the influence of postnatal oxytocin (OXT) on behavioral development, we examined individual variations in basal OXT and suckling‐induced changes in OXT, and their relationship with emotional traits during development. Blood OXT were measured in 20 Holstein heifer calves at 1 (wk1), 2 (wk2), and 6 weeks of age (wk6). The relationships of OXT variables with principal component scores in the open‐field tests at wk2 and 2 months and the number of flinch, step and kick responses during first artificial insemination and machine milking were analyzed. The basal OXT showed individual variability and significantly correlated (wk1 vs. wk2: r = 0.753, P < 0.001; wk1 vs. wk6: r = 0.499, P < 0.05; wk2 vs. wk6: r = 0.476, P < 0.05). The personality traits reflecting a response in the form of escape from novel environments in the open‐field test at wk2 were inversely correlated with basal OXT at wk1 (r_s = ?0.640, P < 0.01) and wk2 (r_s = ?0.447, P < 0.05). However, none of the behavioral variables after 2 months correlated with OXT. These findings suggest that, postnatal OXT might be related to behavioral characteristics in novel environments only during the early stages of life.     

Serum haptoglobin concentration in cattle

To obtain a basal concentration of serum Haptoglobin (Hp) in cattle in Taiwan, Hp concentrations were measured from serum samples collected from 10 healthy heifers, every week for one year. The values were also compared with those collected from 15 cows diagnosed with postpartum metritis. The heifers were successfully impregnated by artificial insemination six months after the tests. Hp concentrations were also measured in the serum collected from 11 other cows within 3 weeks after parturition. The Hp assay developed in this study gave a good correlation (r=0.893)with Western blotting. The Hp concentration of 454 serum samples from the 10 heifers had a mean value of 83.6 +/- 34.1 mg/l, and there was no significant difference among individual heifers. The basal value of Hp in heifers was calculated as less than 73.6 mg/l. No significant difference in Hp concentration was observed among the 10 heifers during cold and warm seasons (19.8 +/- 2.2 degrees C vs 27.3 +/- 1.4 degrees C), or before and after pregnancy. The mean serum Hp concentration from cows suffering from postpartum reproductive disorders was 1133.5 +/- 627.1 mg/l, which was significantly greater than the serum of healthy heifers and postpartum cows (104.6 +/- 61.0 mg/l) (P<0.05). These results demonstrate that Hp concentration may be a useful indicator for cows with postpartum reproductive disorders.     

Shade and water misting effects on behavior, physiology, performance, and carcass traits of heat-stressed feedlot cattle

One hundred twelve crossbred feedlot heifers were used in two experiments to assess the impact of heat stress and its relief by shade and(or) water misting on behavior, physiology, performance, and carcass traits. Treatments were 1) no shading or misting (CONT); 2) only misting (MIST); 3) only shading (SHADE); and 4) shading plus misting (SHMI). Head in the feed bunk, head in or above the waterer, walking, standing, and lying behaviors were observed. Rectal temperature, respiration rate, and carcass traits were measured, as well as DMI, ADG, and feed:gain. Dietary NEm and NEg concentrations were calculated from performance data. In Exp. 1, (32 heifers; average BW 288 kg) the CONT heifers spent more time lying down than all others (P < 0.01). In addition, CONT heifers spent less time (P < 0.01) standing than SHADE and MIST heifers. Misting decreased (P < 0.01) rectal temperature and MIST as well as SHADE lowered (P < 0.05) respiration rates. In Exp. 2 (80 heifers; average BW = 336 kg), lying and walking behaviors did not differ among treatments, but shade increased (P < 0.01) standing behavior in heifers. The MIST cattle performed less (P < 0.05) head-above-water behavior than unmisted cattle. Rectal temperatures did not differ among treatments, but respiration rate was lower in shaded than in unshaded heifers (P < 0.05). Shaded compared with unshaded heifers had greater DMI (9.46 vs 8.80 +/- 0.14 kg/d, P < 0.01) and ADG (1.6 vs 1.41 +/- 0.1 kg/d, P < 0.01). Heifers provided with shade reached their target BW 20 d earlier than the unshaded heifers and differed in final BW (547 vs 520 +/- 6 kg, P < 0.01). Feed:gain and calculated NEg and NEm concentrations did not differ among treatments, and carcass traits were generally similar among treatments. In conclusion, cattle without shade had a physiological and behavioral stress response to heat that negatively affected productivity. Providing shade for beef cattle was a suitable solution to decrease heat stress and to lower the negative effects of heat on performance, whereas misting was largely ineffective.     

Polymorphisms in the bovine HSP90AB1 gene are associated with heat tolerance in Thai indigenous cattle

Heat shock proteins act as molecular chaperones that have preferentially been transcribed in response to severe perturbations of the cellular homeostasis such as heat stress. Here the traits respiration rate (RR), rectal temperature (RT), pack cell volume (PCV) and the individual heat tolerance coefficient (HTC) were recorded as physiological responses on heat stress (environmental temperatures) in Bos taurus (crossbred Holstein Friesian; HF) and B. indicus (Thai native cattle: White Lamphun; WL and Mountain cattle; MT) animals (n = 47) in Thailand. Polymorphisms of the heat shock protein 90-kDa beta gene (HSP90AB1) were evaluated by comparative sequencing. Nine single nucleotide polymorphisms (SNP) were identified, i.e. three in exons 10 and 11, five in introns 8, 9, 10 and 11, and one in the 3′UTR. The exon 11 SNP g.5082C>T led to a missense mutation (alanine to valine). During the period of extreme heat (in the afternoon) RR and RT were elevated in each of the three breeds, whereas the PCV decreased. Mountain cattle and White Lamphun heifers recorded significantly better physiologic parameters (p < 0.05) in all traits considered, including or particularly HTC than Holstein Friesian heifers. The association analysis revealed that the T allele at SNP g.4338T>C within intron 3 improved the heat tolerance (p < 0.05). Allele T was exclusively found in White Lamphun animals and to 84% in Mountain cattle. Holstein Friesian heifers revealed an allele frequency of only 18%. Polymorphisms within HSP90AB1 were not causative for the physiological responses; however, we propose that they should at least be used as genetic markers to select appropriate breeds for hot climates.     

Vaccination of cattle against brucellosis using either a reduced dose of strain 19 or one or two doses of 45/20 vaccine

SUMMARY Three groups, each of 14 mature Jersey heifers, were vaccinated. They were mated about 2 months later and those that became pregnant were challenged at about 6.5 months of pregnancy by the conjunctival application of virulent Brucella abortus. Group 1 heifers received 2 doses of B. abortus 45/20 vaccine 2 months apart. Only 5 of the 14 heifers became pregnant, and of these 5 only one resisted challenge. Group 2 heifers received only one dose of 45/20 vaccine, 5 of the 10 challenged resisted infection. Group 3 heifers received 3 × 10⁸ cfu of strain 19. Six of the 10 heifers challenged resisted infection. All of 5 non-vaccinated control cattle became infected. It appeared advantageous to give only one dose of 45/20 rather than 2 as presently recommended. A single dose of 45/20 vaccine induced resistance to virulent B. abortus approximately equal to that given by the reduced dose of strain 19. One dose of 45/20 vaccine stimulated transient serological positivity in 2 of 28 heifers whereas the reduced dose of strain 19 gave rise to persistent titres in 2 of 14 vaccinated heifers.     

Behavioral sampling techniques for feedlot cattle

Continuous observations are an accurate method for behavioral measurements but are difficult to conduct on large numbers of animals because of extensive labor requirements. Thus, we sought to develop methods of behavioral data collection in feedlot cattle production systems that reasonably approximated continuous sampling. Standing, lying, feeding, drinking, and walking behaviors were examined from 224 h of continuous video from 64 heifers. Experiment 1 (n = 24 heifers) compared continuous behavioral sampling techniques (Continuous) with scan sampling using intervals of 1, 5, 10, 15, 30, and 60 min and time sampling (a technique for the periodic recording of behavior) for the first 10 min out of every 60 min. Means for each scan sampling method did not differ in estimated percentage of duration of behaviors (P > 0.05) from continuous sampling, except for scan sampling with a 60-min interval. Scan sampling with a 60-min interval differed from more frequent scan sampling intervals for all behaviors except lying. Scan sampling with short intervals (1 and 5 min) was correlated highly with Continuous for all behaviors. The longer the scan interval, the lower the correlations, especially for behaviors with short duration. Time sampling was not an accurate technique for measuring the sampled behaviors. Focal animal sampling (using continuous sampling of individuals) indicated that one heifer was representative of the entire pen of 10 animals (Continuous) for all maintenance behaviors except drinking. Scan sampling methods (1-, 5-, 10-, and 15-min intervals) were accurate methods of behavioral sampling for feedlot cattle, but scan intervals of 30 or 60 min were less accurate and less precise. Time sampling was not an accurate method because it overestimated standing and underestimated lying behaviors. Experiment 2 (n = 40 heifers) investigated the number of focal animals required to accurately represent continuous behavioral sampling for all animals. Focal animal sampling was accurate for most behaviors using as few as 1 animal out of 10 but was not an accurate method for drinking behavior unless 40% of the animals in the pen were observed. Estimates of sample sizes needed for experimental protocols are provided. Behavioral means, standard deviations, and coefficients of variation are presented along with estimates of required sample sizes. These results validate accurate, precise, and efficient methods for quantifying feedlot cattle behavior.     

Time budgets of group-housed pigs in relation to social aggression and production

Commercial producers house growing pigs by sex and weight to allow for efficient use of resources and provide pigs the welfare benefits of interacting with their conspecifics and more freedom of movement. However, the introduction of unfamiliar pigs can cause increased aggression for 24 to 48 h as pigs establish social relationships. To address this issue, a better understanding of pig behavior is needed. The objectives of this study were to quantify time budgets of pigs following introduction into a new social group and how these changed over time and to investigate how social aggression influences the overall time budgets and production parameters. A total of 257 grow-finish Yorkshire barrows across 20 pens were introduced into new social groups at 10 wk of age (~23 kg) and observed for aggression and time budgets of behavior at four periods: immediately after introduction and 3, 6, and 9 wk later. Pigs were observed for the duration of total aggression and initiated aggression (s) for 9 h after introduction and for 4 h at 3, 6, and 9 wk later. Time budgets were created by scan sampling inactive, movement, ingestion, social, and exploration behaviors every 2 min for 4 h in the afternoon and summarizing the proportion of time each behavior was performed by period. The least square means of each behavior were compared across time points. Pigs spent most of their time inactive. In general, the greatest change in pig behavior was observed between introduction and week 3 (P < 0.003), with gradual changes throughout the study period as pigs became more inactive (week 3 vs. week 6: P = 0.209; week 6 vs. week 9: P = 0.007) and spent less time on other behaviors. Pigs’ nonaggressive behavior and production parameters were compared with aggression using generalized linear mixed models. The time pigs spent on nonaggressive behaviors was negatively related to aggression (P < 0.045) with few exceptions. Initiated aggression after introduction was negatively related to loin muscle area (P = 0.003). These results show how finishing pigs spend their time in commercial facilities and indicate that behavior continues to change for up to 9 wk after introduction into a new social group. Efforts to reduce chronic levels of aggression should focus on promoting nonaggressive behaviors, such as exploration and movement, after the initial fighting that occurs immediately after introduction has waned, and should be implemented for up to 9 wk after introduction into new social groups.     

Plasma hormone and metabolite concentrations involved in the somatotropic axis of Japanese Black heifers in association with growth hormone gene polymorphism

Bovine growth hormone (bGH) gene polymorphism of leucine (Leu)-threonine (Thr) (allele A), valine (Val)-Thr (allele B), and Val-methionine (Met) (allele C) at codons 127 and 172 was shown to relate with carcass trait variations in Japanese Black cattle. In this study, 10-mo-old Japanese Black heifers with growth hormone (GH) genotypes AA, AB, BB, AC, BC, and CC (N = 141) were compared for basal GH, insulin-like growth factor-1 (IGF-1), insulin, ghrelin, glucose, and nonesterified fatty acid (NEFA) concentrations. Growth hormone release was also measured as response to growth hormone–releasing hormone (GHRH) (0.4 μg/kg body weight [BW]) using 18 heifers with GH genotypes AA, BB, and CC (n = 6 for each group). The genotype AA heifers showed the greatest BW among genotypes (P < 0.05). Genotype AC, BC, and CC heifers showed greater GH concentrations than genotype AA, AB, or BB heifers, in which genotype CC heifers had the highest concentrations (P < 0.05). However, IGF-1 concentrations did not significantly differ. The genotype AA and BB heifers had a greater GH release at 60 min following GHRH injection than did the genotype CC heifers. The area under the curve (AUC; P < 0.07) and incremental area (IA; P < 0.08) of GH responses to the GHRH challenge tended to be the highest in the genotype AA heifers and the lowest in the genotype CC heifers. In conclusion, GH gene polymorphism altered GH, which may have contributed to differences in BW and carcass traits among genotypes.     

Differentiation of sexual behavior in cattle, sheep and swine

Gonadal steroid hormones influence an animal's sexual behavior through two primary means. During development they affect differentiation of the brain (primarily in males), and after puberty, circulating concentrations of steroids influence expression of sexual behaviors. In mammals, sexual behaviors of females are regarded as inherent (independent of steroids secreted by the developing ovary). Males, on the other hand, must undergo active differentiation that is brought about by actions of testicular steroids on the brain during discrete sensitive periods of early development. Sexual differentiation in mammals is referred to as processes of defeminization and masculinization. Defeminization is loss of behavioral traits inherent to females and occurs prenatally in sheep but postnatally in swine. Comparative data are lacking for cattle, but preliminary evidence indicates prenatal defeminization of sexual behaviors. Masculinization is acquisition of behavioral traits characteristic of males. Adult females of all three species show mounting behavior after prolonged treatment with testosterone, and in cattle and swine, there is, as yet, no strong evidence that males undergo masculinization of sexual behaviors. In sheep, limited observations are suggestive of two sensitive periods for masculinization; one prenatally and one postnatally. The earlier concept that differentiation of sexual behaviors in mammals occurs prenatally in species with a long gestation and postnatally in species with a short gestation must now be modified in view of recent findings in swine, in which defeminization occurs postnatally. Further studies will likely identify additional species differences with respect to differentiation of sexual behaviors.     

Changes in concentrations of plasma immunoreactive follicle-stimulating hormone, luteinizing hormone, estradiol-17beta, testosterone, progesterone, and inhibin in heifers from birth to puberty

This study was designed to clarify the characteristics of changes in plasma concentrations of reproductive hormones in heifers from birth to puberty. Weekly or daily hormonal changes were observed in 39 heifers. Daily changes in the concentration of follicle-stimulating hormone (FSH) demonstrated a consistent cycle of hormone changes over a 7- to 8-day period in heifers from approximately 10 days to 9 months old. Weekly changes in reproductive hormones showed that there were three brief periods in heifers between birth and puberty in which dramatic changes occur. The first period was the first week after birth, during which a reciprocal relationship between steroid hormones and gonadotropins was observed. At birth, the concentrations of steroid hormones were higher than those at any other age. These hormone levels rapidly decreased within the first week after birth. Gonadotropin levels, however, increased from birth to 1 week of age. The second period of major change was at approximately 4 weeks of age when there was an increase in the concentrations of luteinizing hormone (LH), estradiol-17beta, testosterone, and immunoreactive inhibin. The third period was the last 5 weeks before the first ovulation, when there was an increase in the concentrations of estradiol-17beta followed by an increase in (LH). These results suggest that regular hormone changes start from 10 days after birth and that the periods from birth to 4 weeks of age and the last 5 weeks before the first ovulation in heifers are important to the development of reproductive functions before puberty.     

Leather quality of beefalo‐Nellore cattle in different production systems

The aim was to compare the effects of two production systems on performance, carcass traits and physical‐mechanical characteristics of leather from Beefalo‐Nellore steers and heifers and to determine if the response to the production system was similar for both genders. A total of 40 Beefalo‐Nellore cattle, 20 steers and 20 heifers, were evaluated. Animals were divided into two production systems: slaughtered at 15 (intensive system) or 26 (extensive system) months of age. In the intensive system, all animals received a ration containing 600 g/kg corn silage and 400 g/kg concentrate. In the extensive system, animals were kept on a pasture predominantly based on Brachiaria sp. and supplemented with 2 kg/day concentrate. In the intensive system, there was no difference in slaughter weight (470 kg body weight) between steers and heifers but steers in the extensive system had greater slaughter weight than heifers (463 and 428 kg body weight, respectively). Leather weight was higher for animals in the intensive than extensive system but there was no difference in leather weight once excess fat was removed. Leather quality from Beefalo‐Nellore cattle slaughtered at 15 or 26 months of age is similar although carcass yield is higher for cattle slaughtered at a younger age.     

Seasonal and sex differences in area preference and behavior of young cattle just after long distance transport

To determine seasonal and sex differences in behavioral motivation of cattle just after long transport, 54 Japanese Black × Holstein cattle were observed at 5 min intervals for 2 h just after 25‐h transport by road and ferry. The stocking pen (12.0 × 9.5 m) consisted of an eating area (near a feeding alley), a drinking area (near water bowls) and a resting area (all areas except for other two areas). First, the effect of season was determined with heifers in summer (n = 12: 7.9 ± 0.6 months of age; 292.0 ± 18.5 kg) and autumn (n = 19: 8.2 ± 0.6 months of age; 295.8 ± 15.5 kg). The mean temperature on the observation day was 28.5 (max: 34.5, min: 24.5)°C in summer and 20.3 (max: 26.5, min: 16.4)°C in autumn. Percentage of cattle staying in each area was different by season (χ² = 22.0; P < 0.01). In summer, the percentage of cattle staying in the drinking area (26.7%) was greater than the expected percentage (16.7%). Percentage of cattle staying in the eating area was greater in both seasons (31.3% in summer and 53.6% in autumn) than the expected percentage (16.7%). However, the mean percentage of cattle performing each behavior was not significantly different by season. Secondly, the effect of sex was determined with steers (n = 23: 7.6 ± 0.6 months of age; 301.9 ± 20.7 kg) and heifers (n = 19: same as above) in autumn. Although the percentage of cattle staying in each area was different by sex (χ² = 20.2; P < 0.01), the percentages of steers (25.5%) and heifers (53.6%) staying in the eating area were both greater than the expected percentage (16.7%). However, percentage of animals performing each behavior was not different by sex. These results recommend to stockpersons that they should install additional troughs for hay and water into a pen just after long distance transport, since the number of cattle that can eat and drink at the same time was limited.     

EVALUATION OF A HARDJO-POMONA VACCINE TO PREVENT LEPTOSPIRURIA IN CATTLE EXPOSED TO A NATURAL CHALLENGE WITH LEPTOSPIRA INTERROGANS SEROVAR HARDJO

SUMMARY The efficacy of a vaccine against Leptospira interrogans serovar pomona and Leptospira interrogans serovar hardjo was evaluated in a group of dairy heifers that were serologically negative at the time of vaccination and later subjected to natural challenge with L. interogans serovar hardjo. Thirty-nine heifers were vaccinated twice, at a one-month interval, with a commercially prepared bivalent vaccine, while 43 unvaccinated heifers were used as controls. After vaccination, microscopic agglutination (MA) titres of serums to L. interrogans serovar hardjo ranged from 32 to 512, and those to L. interrogans serovar pomona ranged from 32 to 2048. Titres resulting from vaccination were short-lived and after the first vaccination the serums of 95% of vaccinated heifers did not react in the MA test by 24 weeks. The first indication of infection in the heifers was noted at week 6, and by week 16, elevated MA titres (≥128) to L. interrogans serovar hardjo had occurred in 62% of unvaccinated heifers and had increased to 85% by week 24. At week 18, 18% of the vaccinated heifers and 56% of the unvaccinated heifers had leptospiruria (p<0.01); after 22 weeks, 13% of the vaccinated heifers and 58% of the unvaccinated heifers showed evidence of leptospiruria (p<0.01).     

Intake,digestibility, performance,and carcass traits of beef cattle of different gender

The performance, intake, feed efficiency, and carcass traits of beef cattle from different gender profile were assessed. Fifteen animals (five steers, five spayed heifers, and five intact heifers) with ±250 kg of initial body weight were randomly assigned in individual pens and fed the same diet for 106 days. At the end of the trial, all the animals were slaughtered and the pH, temperature, and weight of the carcass were recorded. The right side of each carcass was then separated into chuck, shoulder, flank sirloin, and round for evaluation of commercial cuts yield. The left carcass sides were ribbed between the 12th and 13th ribs where the rib eye area and fat thickness measurements were taken. The 9th–11th rib section was removed from the left half carcass and then dissected into muscle, fat, and bones in order to estimate carcass composition. Gender had no effect (P > 0.05) on performance, intake, digestibility of dry matter and all the nutrients evaluated, feed efficiency, and carcass characteristics. It can be concluded that steers and heifers (spayed or not) have the same potential to produce beef. From a productive and welfare standpoint, there is no reason to spay heifers.     

Thyroid activity in relation to feed intake, growth rate and feed conversion in growing heifers

Phenotypic and genetic parameters for thyroid activity (T4 serum level, T4 apparent distribution volume, T4 fractional turnover rate and T4 degradation), and for certain production traits (roughage dry matter intake, daily weight gain and roughage dry matter/kg weight gain), were investigated in cattle. In the experiment, 480 growing heifers were studied, daughters of 20 AI sires previously tested for thyroid activity. Repeatabilities for thyroid traits 2-3 months apart varied, with an average 0.3-0.6 for the different traits. Heritability estimates based on sire components were 0.1-0.4 for the thyroid traits, 0.16 +/- .10 for roughage intake and 0.18 +/- .11 for daily gain. The sire component for feed efficiency (roughage dry matter/kg weight gain) was 0, and genetic correlations between thyroid traits and the production traits in growing heifers were low with large standard errors.     

Effect of selection for growth traits on age and weight at puberty in bovine females

This 20-yr study, using 584 beef heifers born in the spring of 1984 or 1985, was conducted to determine whether selection for growth traits affected age and weight at puberty. Heifers were from three Hereford lines selected for weaning weight, final weight, and final weight plus muscling score, a control line and a line of Angus cattle. In addition, heifers from reciprocal crosses among the selection lines, control and Angus groups were evaluated. Intact bulls and androgenized heifers fitted with marking harnesses were used to aid in detection of estrus for heifers born in 1984 and 1985, respectively. The time of puberty was identified by the first behavioral estrus. During both years, heifers were weighed at 56-d intervals; these weights were used to calculate weight at puberty. Mean age at puberty was determined using survival analysis; percentages of heifers that were pubertal by the end of the study were transformed to logits for analysis. Heifers born in 1985 were heavier (P less than .05) at puberty than those born in 1984. Heifers in lines selected for growth traits were younger at puberty (P less than .05; 20 d) than were heifers in the control line because of combined direct and maternal genetic effects. Heifers from the final weight, control (P less than .05) and weaning weight lines (P less than .10) weighed less at puberty than Angus heifers; selection line x Angus crossbred heifers were heavier at puberty (P less than .05) than their respective pureline or purebred contemporaries due to heterotic effects. Selection for weaning weight, final weight or final weight plus muscling score did not have a detrimental effect on age at puberty in heifers.     

Beef heifer production as affected by indoor feed intensity and slaughter age when grazing semi-natural grasslands in summer

Only limited knowledge exists on how to produce high-quality beef carcasses when the cattle also are grazing semi-natural grasslands for nature conservation purposes. The objectives of the two factorially-designed trials were to determine the effects of indoor feed intensity (low vs. high) and slaughter age (18 vs. 22 months) on performance and carcass quality of beef heifers, raised from weaning until slaughter and grazing semi-natural grasslands during growing seasons. In the first trial, 56 Charolais heifers were used of which 28 were fed only grass-clover silage ad libitum (low; CL), and another 28 heifers were fed 2.0 kg of grain daily in addition to the silage (high; CH). In the second trial, 28 Angus heifers were fed grass-clover silage at 80% ad libitum (low; AL), whereas another 28 heifers were fed silage ad libitum (high; AH). According to a national nature conservation score, the grazing pressure on the semi-natural grassland was classified as having been satisfactory to maintain the floristic diversity as no litter had been accumulated onto the sward. From weaning until slaughter, no difference in average daily gains (ADG) was found between the CH and the CL, whereas the AH had higher ADG than the AL (693 vs. 573 g, P < 0.001). Heifers in both trials had higher carcass weights and more fat, Charolais heifers also had better conformation and Angus heifers had higher dressing percentage at 22 months than at 18 months of slaughter age (P < 0.05). In conclusion, carcass traits in both trials were more affected by slaughter age than by feed intensity and desirable grazing effects were achieved on the pasture.     

Association analysis of novel polymorphisms in 2′, 5′‐oligoadenylate synthetase gene with reproductive traits in indigenous and cross‐bred cattle of Indian Origin

2′, 5′‐Oligoadenylate synthetases (OAS) are important components of an interferon‐mediated antiviral pathway. No polymorphisms in exonic regions of bovine OAS1 gene have been identified and associated with reproduction traits. The objective of the study was to detect and evaluate the effects of mutations in exonic region of bovine OAS1 gene with reproduction traits in cattle. DNA samples collected from 250 individual cows of two Indian dairy breeds (Sahiwal and Frieswal) of cattle were used in the study. The genetic variants of the OAS1 gene were identified with polymerase chain reaction–single‐strand conformation polymorphism (PCR‐SSCP) and sequence analysis using seven set of primer pairs. The PCR‐SSCP analysis revealed polymorphism in the fragments comprising of exon 2, exon 5 and first fragment of exon 6 while the fragments of exons 1, 3, 4 and second fragment of exon 6 were monomorphic in Sahiwal and Frieswal cattle. The mutations in the amplified region comprising of exon 2 were found to have significant association with age at first breeding and calving, service period, dry period and pregnancy rate. Significant associations were found between SNPs in the exon 5 and service and dry periods of the animal, whereas the genetic variants in the first fragment of the exon 6 showed significant association with age at first breeding and calving. To our knowledge, this study demonstrated for the first time that the polymorphisms in OAS1 gene were associated with reproductive traits and it can be chosen as a candidate gene for improvement of reproductive performance of cattle.     

Body weights at weaning and 18 months of Zebu, Brown Swiss, Charolais and crossbred heifers in south-east Mexico

The objective of this study was to evaluate the body weights up to 18 months of age of 12 breed groups of Zebu (Z), Brown Swiss (BS) and Charolais heifers (CH), and their crosses under tropical conditions. A total of 1434 data on weaning weights adjusted to 240 days (WW8), average daily gain to 240 days (ADG8) and 1025 body weights adjusted to 550 days (BW18) and average postweaning daily gain (ADG18) of heifers born from 1981 to 1995 were used. Cows and calves remained together from birth to weaning and grazed on Guinea grass (Panicum maximum). Years of birth were grouped in three periods, because of the small numbers of observations per year (1981–85, 1986–90 and 1991–95). Similarly, months of birth were grouped in three seasons: dry (February to May), rainy (June to September) and windy and rainy (October to January). Ages of dams were classified in six groups (≤3, 4, 5, 6, 7 and ≥8 years). Breed groups were animals with 12.5%, 25.0%, 50.0%, 62.5%, 75.0% and 100% BS genes and 25.0%, 50.0%, 75.0% and 100% CH genes and also Z and undefined crossbred animals. Data were analysed using a fixed model that included effects of period, and season of birth, age of dam and breed group of heifer. Analyses of variance showed significant (p < 0.05) effects of period, season and breed group for all traits. However, parity was significant (p < 0.05) only for WW8 and ADG8. Interactions among main factors were not significant (p > 0.05). Z heifers gained the least weight to weaning but were similar to BS at 18 months of age. CH were heavier at 18 months of age than BS heifers, but not at weaning. Body weights at 18 months of age of 1/8 and 1/4 BS crossbred heifers were similar (p > 0.05) and lower than F₁ (BS × Z) (p < 0.05); however, the later and higher grades of BS had the highest body weights at 18 months of age and were similar to CH and 1/4 CH × 3/4 Z heifers. Undefined crossbred heifers had better performance than the Z breed group. Environmental factors were important sources of variation for pre‐ and postweaning traits. Under the conditions of this study, crossbred heifers generally performed better than Z heifers up to 18 months of age.     

Shade effects on performance,carcass traits,physiology, and behavior of heat-stressed feedlot heifers

To determine whether shade influences performance, carcass traits, immunology, respiration rate, and behavior of cattle under conditions similar to those in commercial feedlots, we used 168 heifers in 12 soil-surfaced pens. Six pens were shaded with a galvanized steel-roofed shade (approximately 4 m high), allowing for 2.12 m2 of shade/heifer, and six pens served as the unshaded control. Heifers were fed a 90% concentrate diet during the 121-d trial that began in mid-June, performance variables (DMI, BW, ADG, gain:feed) were measured, and dietary concentrations of NEm and NEg calculated from performance data. A blood sample was collected to assess immune measures. Respiration rates and behaviors (feeding, drinking, walking, standing, lying, agonistic, and bulling) also were measured during the study. Carcass data (yield grade, kidney, pelvic, and heart fat, longissimus muscle area, hot carcass weight, quality grade, liver abscess rate, and incidence of dark-cutting beef) were collected at slaughter. Shaded heifers had higher (P < 0.05) DMI, ADG, and final BW than unshaded heifers. The gain:feed ratio and calculated dietary NEm and NEg concentrations did not differ (P > 0.26) between treatments. Most carcass traits did not differ between treatments, but more (P < 0.02) carcasses ofheifers in shaded pens graded USDA Choice than those in unshaded pens, which resulted primarily from the incidence of dark cutters being decreased (P < 0.04) by approximately half in carcasses from shaded compared with unshaded heifers. Respiration rate and percentage of circulating neutrophils were decreased (P < 0.01) for shaded compared with unshaded heifers. The treatment x time of day effect was significant (P < 0.05) for all behavioral measurements. Shaded heifers spent more time laying down (0800, 1200, and 1500, P < 0.05) and less time standing (1200 and 1500, P < 0.05) than unshaded heifers. Agonistic behavior was less (P < 0.05) for shaded than for unshaded heifers at 1900 and 2000, and bulling was less (P < 0.05) for-shaded than unshaded heifers at 2100. Results suggest that shade improved performance and altered behavior by feedlot heifers during the summertime in West Texas.