Performance of ad libitum fed dairy calves weaned using fixed and individual methods

The increasing availability of automated milk dispensers on dairy farms facilitates ad libitum milk supply but weaning calves from high milk allowances is challenging. This study evaluated effects of gradual weaning methods on starter intake, growth, selected blood parameters and weaning distress in ad libitum fed dairy calves during weaning and early post-weaning periods. Thirty-six male Holstein (n = 30) or crossbred (n = 6) calves were individually housed from days 2 to 14 of age and had ad libitum access to milk replacer (MR) from teat buckets. From days 15 to 84 of age, calves were grouped and had ad libitum access to MR, starter, straw and water from automated feeders. At day 35, calves were blocked (age and breed), and randomly assigned to a weaning method: (1) linear fixed (LIN), MR supply was stepped down to 6 l/day on day 36, and linearly reduced between days 36 to 63 from 6 to 2 l/day. (2) Step-down (STEP), MR supply was stepped down to 6 l/day from days 36 to 48, 4 l/day from days 49 to 56 and 2 l/day from days 57 to 63. (3) Dynamic (DYN), at day 36, MR supply was reduced for each individual calf to 75% of the average voluntary consumption between day 29 and 35, then maintained for 9 days, reduced to 50% for 10 days, and to 25% for 9 days. The DYN calves received more MR during weaning than LIN calves, whereas STEP calves had intermediate MR intake. Starter intake was not affected by weaning method. The DYN calves (1.33±0.08 kg/day) grew faster and were heavier than STEP calves (1.10±0.08 kg/day) during post-weaning period, whereas no difference was observed between LIN calves (1.23±0.08 kg/day) and others. At days 70 and 84, concentrations of β-hydroxybutyric acid were higher in LIN calves compared to STEP and DYN calves. Hair cortisol concentrations were not affected by weaning method. During the gradual weaning process CP intake seemed to recovered earlier than metabolizable energy (ME) intake in all treatments, suggesting that ME rather than CP could be the first limiting factor for growth during weaning. These results highlight the post-weaning benefits of DYN and LIN weaning methods when compared with more abrupt step-down strategies.     

The effect of age at introduction and number of milk-portions on the behaviour of group housed dairy calves fed by a computer controlled milk feeder

This study is an investigation of the effect of age at introduction (6 days versus 14 days) and number of milk-portions (four milk-portions a day versus eight milk-portions a day) on integration into a large dynamic group of calves, fed by a computer controlled milk feeder. Forty calves (Jerseys, Danish Reds and Holstein-Friesians) were allocated equally to the two age conditions (A6 and A14) and the two milk-portion conditions (M4 and M8) in a 2 × 2 factorial design, according to sex and breed, and introduced into the group in pairs (one A6 and one A14). The behaviour of each pair was video-recorded for 8 h from 8 a.m. to 4 p.m. and 1 h from 1 to 2 a.m. on days 1, 8 and 15 after introduction.

The A6 calves performed less licking and sniffing, changed posture more often and tended to spend less time standing than the A14 calves. In the course of time A14 calves lay closer to other calves than the A6 calves.

The M8 calves, which were offered the same daily milk allowance as the M4 calves stood for a longer time in the milk feeding station and the M8 calves also sucked the empty teat more frequently than the M4 calves. Finally, the M8 calves initiated more social play behaviour than the M4 calves. On the first day after introduction the M8 calves lay closer to other calves than the M4 calves.

The results suggest that calves integrate better into a group when introduced at the age of 14 days than at the age of 6 days. Distributing the milk into eight daily milk-portions, rather than four milk-portions in the first period after introduction, increased milk feeder occupancy, which may facilitate learning to use the milk feeder. Surprisingly, more milk-portions also stimulated play behaviour, which is suggested to be due to M8 calves encountering more calves in the milk feeder area.     

Weaning distress in dairy calves: Effects of alternative weaning procedures

The aims of this study were to describe the behavioural responses to weaning from milk in dairy calves, and to compare responses when calves were either weaned abruptly (removal of the milk-feeding system; n = 8 calves) or by substituting warm water for milk in the milk-feeding apparatus for the first 2 days after weaning (n = 8 calves). Calves provided water through the milk-feeding system after weaning seemed to substitute one liquid for the other; calves consumed approximately the same quantity of warm water after weaning (8 kg/day) as they had consumed milk before weaning (9 kg/day). All calves vocalized at weaning, but abruptly weaned calves vocalized at more than three times the rate of calves provided water through the milk-feeding system. On the third day after weaning, when neither treatment group had access to the milk-feeding system, the call rate was similar in the two treatment groups. The abruptly weaned calves were also more active at weaning, as indicated by an increased number of standing bouts compared to calves with continued access to the milk-feeding apparatus. The reduced response to weaning by the calves with continued access to the feeding routine may be due to the gut fill associated with the water intake or to other rewarding properties of the system (e.g. allowing calves to suck on a teat). In conclusion, dairy calves show a strong behavioural response to weaning, but providing calves continued access to the milk-feeding apparatus for 2 days after weaning reduces this response.     

The effect of the macrolide antibiotic tylosin on microbial diversity in the canine small intestine as demonstrated by massive parallel 16S rRNA gene sequencing

Background  

Recent studies have shown that the fecal microbiota is generally resilient to short-term antibiotic administration, but some bacterial taxa may remain depressed for several months. Limited information is available about the effect of antimicrobials on small intestinal microbiota, an important contributor to gastrointestinal health. The antibiotic tylosin is often successfully used for the treatment of chronic diarrhea in dogs, but its exact mode of action and its effect on the intestinal microbiota remain unknown. The aim of this study was to evaluate the effect of tylosin on canine jejunal microbiota. Tylosin was administered at 20 to 22 mg/kg q 24 hr for 14 days to five healthy dogs, each with a pre-existing jejunal fistula. Jejunal brush samples were collected through the fistula on days 0, 14, and 28 (14 days after withdrawal of tylosin). Bacterial diversity was characterized using massive parallel 16S rRNA gene pyrosequencing.     

Effects of early separation on the dairy cow and calf: 2. Separation at 1 day and 2 weeks after birth

This study investigated the effects of separating dairy calves from their mothers at 1 day (early separation) and 14 days (late separation) after birth. Behavioural observations were conducted on 24 Holstein dairy cow–calf pairs during the first 24 h after separation. Before separation, cow–calf pairs were generally inactive. After separation, cows from the late-separation treatment group showed higher rates of calling, movement and placing the head outside the pen, than cows in the early-separation group. Parity did not influence cow behaviour. During the first 2 weeks after calving, cows in the late-separation group (i.e. still with their calves) yielded less milk at milking, a difference at least partly due to the milk consumed by the calf. Milk yields from days 15–150 did not differ between the two groups. After separation, calves in the late-separation group moved and placed their heads outside the pen more often than early-separation calves. During the first 14 days after birth, late-separation calves gained weight at more than three times the rate of those separated early. When introduced to an unfamiliar calf at 6 weeks of age, calves from the late-separation group showed more intense social behaviour towards the unfamiliar calf than did those calves separated early. Thus, the response to separation by both cows and calves increased when calves were separated at 2 weeks rather than 1 day of age, but calves separated at the later age gained more weight and delayed separation appeared to influence the development of calf social behaviour.     

An ivermectin sustained release bolus in cattle: its effects on the tick Ixodes ricinus

Five calves were given an intraruminal bolus orally, designed to release ivermectin for 120 days at the rate of 8 mg/day. This is equivalent to a dose of 40 micrograms/kg/day for a calf expected to weigh 200 kg at the end of the delivery period. Five control calves were given a placebo bolus. On days 7 and 36 after treatment ten nymphs and ten adult female Ixodes ricinus (Linnaeus 1758) were placed in ear bags on the calves. The engorgement rates were monitored for 10 days and subsequent egg production and hatching percentages determined. There were no significant differences between treatment groups for female mortality. However, ivermectin treatment significantly reduced the numbers and weights of engorged females, females laying eggs, and the number of larvae produced on the treated calves was reduced to 3% of that of the control group. The effects on nymphs, although similar, were less consistent than on adults.     

Effects of feeding level and protein content of milk replacer on the performance of dairy herd replacements

It has been suggested that United Kingdom recommendations for feeding the neonatal calf (500 g milk replacer (MR)/day; 200-230 g CP/kg milk powder) are inadequate to sustain optimal growth rates in early life. The current study was undertaken with 153 high genetic merit, male and female Holstein-Friesian calves (PIN2000 = ￡48) born between September and March, with heifers reared and bred to calve at 24 months of age. Calves were allocated to one of four pre-weaning dietary treatments arranged in a 2 MR feeding level (5 v. 10 l/day) × 2 MR protein content (210 v. 270 g CP/kg dry matter (DM)) factorial design. MR was reconstituted at a rate of 120 g/l of water, throughout, and was offered via computerised automated milk feeders. Calves were introduced to pre-weaning diets at 5 days of age and weaned at day 56. During the first 56 days of life, calves offered 10 l MR/day had significantly higher liveweight gains (P < 0.001) than calves fed 5 l MR/day. No significant differences in liveweight gain were found between calves fed 210 g CP/kg DM MR and those fed 270 g CP/kg DM MR from birth to day 56. Differences in live weight and body size due to feeding level disappeared by day 90. Neither MR feeding level nor MR CP content affected age at first service or age at successful service, and with no milk production effects, the results indicate no post-weaning benefits of increased nutrition during the milk-feeding period in dairy heifers.     

Trypanosoma evansi: Therapeutic efficacy of diminazine aceturate in crossbred calves, Bos taurus and B. indicus

The therapeutic efficacy of diminazine aceturate (Berenil) against Trypanosoma evansi infection (surra) in calves was determined. Seven crossbred calves, 8 to 12 months old, were inoculated subcutaneously with 5 × 10⁷ parasites of a virulent strain of T. evansi. All of the calves developed clinical infection and exhibited symptoms associated with chronic surra. Forty-one to forty-four days after inoculation, five of the calves were treated with a single dose of diminazine aceturate at 10 mg/kg body weight intramuscularly. The two remaining calves were left as infected but untreated controls. The treated calves were found free of the infection on repeated blood smear examinations and diagnostic challenge tests in mice 12 hr to 16 days later. One of the five calves, which was treated at an advanced stage of the disease, died on the fifth day after treatment. Splenectomy of the treated calves, 16 to 19 days after treatment, did not result in relapse of parasitemia, indicating that diminazine aceturate at 10 mg/kg had a rapid trypanocidal effect in surra of calves. Both of the controls died of the disease on the 45th and 47th day.     

The effects of feeding high or low milk levels in early life on growth performance,fecal microbial count and metabolic and inflammatory status of Holstein female calves

Gut microbial colonization and immune response may be affected by milk feeding method. The objective of this study was to determine the effects of feeding high or low volumes of milk on fecal bacterial count, inflammatory response, blood metabolites and growth performance of Holstein female calves. Colostrum-fed calves (n = 48) were randomly assigned to either high milk (HM; n = 24) or low milk (LM; n = 24) feeding groups. Low milk-fed calves were fed pasteurized whole milk at 10% of BW until weaning. In HM group, milk was offered to calves at 20% of BW for the first 3 weeks of life. Then, milk allowance was decreased gradually to reach 10% of BW on day 26 and remained constant until weaning on day 51. Calves were allowed free access to water and starter throughout the experiment. Body weight was measured weekly, and blood samples were taken on days 14, 28 and 57. Fecal samples were collected on days 7, 14 and 21 of age for the measurement of selected microbial species. By design, HM calves consumed more nutrients from milk during the first 3 weeks and they were heavier than LM calves on days 21, 56 and 98. High milk-fed calves had greater serum glucose and triglyceride levels on day 14 with no significant difference between groups on days 28 and 57. Blood urea nitrogen was higher in LM calves on day 14, but it was lower in HM calves on day 28. Calves in LM group had significantly greater blood tumor necrosis factor-α (TNF-α) than HM calves throughout the experiment. Serum amyloid A (SAA) concentration was higher in LM calves on day 14. However, HM calves showed higher levels of SAA at the time of weaning. Feeding high volumes of milk resulted in lower serum cortisol levels on days 14 and 28 but not at the time of weaning in HM calves compared to LM counterparts. Lactobacillus count was higher in feces sample of HM calves. Conversely, the numbers of Escherichia coli was greater in the feces of LM calves. Calves in HM group showed fewer days with fever and tended to have fewer days treated compared to LM group. In conclusion, feeding higher amounts of milk during the first 3 weeks of life improved gut microbiota, inflammation and health status and growth performance of Holstein dairy calves.     

Performance of Holstein calves receiving equal quantities of milk at fixed or variable amounts per day during milk-feeding period

Two experiments were conducted to determine the effects of feeding equal quantities of milk during the pre-weaning period through different milk-feeding regimes on calf growth, starter intake and selected blood metabolites. In experiment 1, 44 female Holstein calves (3 days of age and 39.2±4.3 kg of BW) were distributed randomly to one of two milk-feeding programs (1 calf per pen; 22 pens per treatment group): (1) consistent (CONS; 6 l/day of milk from days 3 to 60 and 3 l/day from days 61 to 65 of age) or (2) step-up/step-down (SUSD; 5 l/day of milk from days 3 to 15, 8 l/day from days 16 to 40, 6 l/day from days 41 to 50, 3 l/day from days 51 to 60 and then 2 l/day from days 61 to 65 of age). No difference between treatments was observed in starter consumption, feed efficiency, hip width and heart girth. However, pre-weaning average daily gain (ADG) tended to be greater in CONS than in SUSD calves (0.78 v. 0.70 kg/day; P=0.07). Blood β-hydroxybutyrate at day 45 (pre-weaning) was lower in SUSD than in CONS calves (0.14 v. 0.21±0.013 mmol/l). In experiment 2, 26 male Holstein calves (3 days of age and 39.4±4.1 kg of BW) were assigned at random to one of two milk-feeding protocols (1 calf per pen; 13 pens per treatment group): (1) consistent (CONS; (7 l/day of milk from days 3 to 40 and 2 l/day from days 41 to 45 of age) or (2) step-down (STD; 8 l/day of milk from days 3 to 30, 4 l/day from days 31 to 40 and 2 l/day from days 41 to 45 of age). The milk-feeding program had no effect on the performance measurements, with the exception that ADG (days 15 to 30), starter intake (days 30 to 45) and heart girth (day 45) were greater in STD than in CONS calves. In conclusion, it appears that if the total amount of milk intake is held constant over the course of milk-feeding period, the method of milk feeding would have negligible effects on calf performance.     

Analysis of pre-weaning feeding policies and other risk factors influencing growth rates in calves on 11 commercial dairy farms

Growth rates in pre-weaned calves influence their health, age at first calving and lifetime productivity. Many farms restrict milk rations to encourage solid feed intake and facilitate early weaning, but this can compromise growth. This study determined the milk feeding policies and associated growth rates on 11 commercial dairy farms in South East England, each following their normal management regime. Between 26 and 54 heifers were recruited per farm, providing a final cohort of 492, of which 71% were pure Holstein. Information on calf rearing practices (feeding, weaning, housing) and health was collected via questionnaires and weekly observations. Estimates of actual milk fed (kg solids) between 1 and 63 days were calculated for individual calves. Morphometric data (weight, height, length) were taken at weeks 1, 5 and 9 and at a median age of 7.5 months and growth rates were calculated. Most calves were fed milk replacer via automated feeders (four farms), teat feeder (one) or buckets (four) whereas two farms provided drums of acidified waste milk. Farms fed between 4 and 6 l/day of milk at mixing rates of 10% to 15%, providing 400 to 900 g/day of milk solids. Both skeletal growth rates and average daily weight gain (ADG) increased in the second month of life compared with the first: height growth from 0.17±0.14 to 0.25±0.16 cm/day and ADG from 0.48±0.25 to 0.71±0.28 kg/day. Post-weaning heifers up to 7.5 months had height increases of 0.16±0.035 cm/day and ADG of 0.83±0.16 kg/day. From 1 to 63 days 70% of calves had growth rates <0.7 kg/day and of these 19.6% gained <0.5 kg/day. Mean ADG before 9 weeks varied between farms from 0.52±0.30 to 0.75±0.20 kg/day. This was related to the amount of milk fed at both a farm and individual calf level. Increasing the total milk solids fed between 1 and 63 days from 20.4 to 46.3 kg (the 10^th to 90^th percentile observed) was associated with an increase of 0.11 kg/day ADG. All farms had a wide variation in growth rates despite single feeding policies. Higher circulating immunoglobulin G and IGF1 concentrations were associated with better growth, whereas low temperatures in month of birth, high scores for diarrhoea, respiratory and umbilical disease and large birth size reduced growth. Many commercially grown dairy heifers therefore experienced growth restriction in the pre-weaned period, potentially reducing their health, welfare and productivity.     

Tylosin production by Streptomyces fradiae using raw cornmeal in airlift bioreactor

Using a 50-l airlift bioreactor, for the effective production of tylosin from Streptomyces fradiae TM-224 using raw cornmeal as the energy source, various environmental factors were studied in flask cultures. The maximum tylosin concentration was obtained at 32 degrees C and pH between 7.0 and 7.5. When seed was inoculated after 24 h of culture, the maximum tylosin concentration, 5.7 g/l, was obtained after 4 days of culture. Various concentrations of raw cornmeal were tested to investigate the optimum initial concentration for the tylosin production. An initial raw cornmeal concentration of 80 g/l gave the highest tylosin concentration, 5.8 g/l, after 5 days of culture. Of the various nitrogen sources, soybean meal and fish meal were found to be the most effective for the production of tylosin. In particular, with the optimal mixing ratio, 12 g/l of soybean meal to 14 g/l of fish meal, 7.2 g/l of tylosin was obtained after 5 days of culture. To compare raw cornmeal and glucose for the production oftylosin in the 50-1 airlift bioreactor for 10 days, fed-batch cultures were carried out under the optimum culture conditions. When raw corn meal was used as the energy source, the tylosin production increased with increasing culture time. The maximum tylosin concentration after 10 days of culture was 13.5 g/l, with a product yield from raw cornmeal of 0.123 g/g of consumed carbon source, which was about 7.2 times higher than that obtained when glucose was used as the carbon source.     

Liquid supplementation of grazing cows and calves

One hundred and one Angus cows (average weight 614 kg) and their bull calves (average weight 213 kg) grazing improved summer pastures were used to determine cow and calf intake of liquid supplement, and its effect on forage intake and performance. Forty-seven pairs had access to a 410 g CP/kg DM molasses-based liquid supplement in an open feeder and 54 pairs were not supplemented. The study was conducted in southwestern Montana from July 28 to October 3, 1997. Cows consumed significantly more supplement (0.3 kg/day) than calves (0.1 kg/day) but both consumed 0.5 g/kg bodyweight per day. Supplemented cows gained 0.12 kg/day more (p<0.05) than unsupplemented cows; however, there was no difference (p>0.10) in body condition score change. Average daily gain by supplemented calves was 30% greater (p<0.01) than average daily gain by unsupplemented calves. Forage intake (g/kg body weight) by both supplemented cows and calves was 64% greater (p<0.01) than forage intake by unsupplemented cows and calves. There was no difference (p>0.10) in milk intake between supplemented and unsupplemented calves. There was no difference (p>0.10) in time spent at the supplement feeder between cows and calves, averaging 5.0 min/day. Time at the feeder was lowest for 7-year-old cows, intermediate for 6- and 8-year-old cows, and highest for 9-year-old cows (p<0.10). There was no difference (p>0.10) in supplement feeding bouts/day between age groups of cows. Calf liquid supplement intake (g/kg body weight) and time spent at the supplement feeder were similar to intake and time spent at the feeder by cows. Liquid supplementation increased forage intake and average daily gain by cows and calves grazing improved forages in late summer. The cost for additional weight gained by the supplemented calves was US$ 0.33/kg and October cattle prices in Montana were US$ 1.64/kg. Liquid supplementation was cost effective under the conditions of this study.     

Gastrointestinal development of dairy calves fed low- or high-starch concentrate at two milk allowances

The objective was to study the effect of type of concentrate with varying starch and fibre content on growth and gastrointestinal development in preweaned dairy calves. Thirty-two newborn Danish Holstein male calves were allocated to four treatment groups in eight blocks of four calves. An experimental low-starch, high-molasses, high-fibre (EXP) concentrate or a traditional high-starch (TRA) concentrate were fed either at a high (HIGH; 2 × 3.2 kg/day) or a low (LOW; 2 × 1.6 kg/day) whole milk allowance in a 2 × 2 factorial design. TRA contained 350 and EXP 107 g starch/kg dry matter (DM), whereas the NDF content was 136 and 296 g/kg DM, respectively. Metabolizable energy (ME) was 11.2 and 12.2 MJ ME/kg DM in EXP and TRA, respectively. All calves had free access to artificially dried grass hay (9.8 MJ ME/kg DM). Four calves were culled during the experiment. The calves were euthanized either at 38 (12 calves) or 56 days (16 calves) of age. Evaluated across both slaughter ages, there was no difference between TRA and EXP in concentrate and hay intake, rumen weight and papillation. EXP resulted in increased villi number in duodenum and jejunum compared with TRA. Concentrate intake and reticulo-rumen weight was higher for LOW compared with HIGH milk allowance, whereas live weight gain was 20% lower. The results show that a low-starch, high-molasses, high-fibre concentrate with 8% lower ME content tended to reduce daily gain compared with a traditional calf starter concentrate, but resulted in similar ruminal development in preweaned calves both on a high and a low milk allowance fed along with grass hay. Furthermore, the results suggest that the experimental concentrate stimulated intestinal villi growth over that of the traditional concentrate.     

Dacarbazine induces genotoxic and cytotoxic germ cell damage with concomitant decrease in testosterone and increase in lactate dehydrogenase concentration in the testis

Treatment of cancers with cytotoxic agents such as alkylating drugs often, but not always results in transient to permanent testicular dysfunction. The present study was planned to investigate the effects of dacarbazine [5-(3,3-dimethyltriazeno) imidazole-4-carboxamide] on testicular function in mice. Swiss albino mice (9-12 weeks old) were treated with 0, 5, 25, 50, or 100mg/kg body weight/day dacarbazine (i.p.) for 5 days at intervals of 24h between treatments. Mice were sacrificed on days 7, 14, 21, 28, 35, 49, and 70 after the last treatment (6 mice/dose/sample time), and the epididymal sperm count, sperm motility, sperm morphology, testicular histopathology (qualitative histopathology, seminiferous tubular diameter and epithelial height), and intra-testicular levels of testosterone and lactate dehydrogenase were assessed. Dacarbazine decreased the body weight only on day 28 at 25mg/kg dose-level, but increased the paired testes weights at 50mg/kg on day 7, at 25-100mg/kg on day 14, and at 25 and 50mg/kg on day 21 (P<0.05-0.01; one-way ANOVA and Bonferroni's post hoc test). The sperm count was decreased on all sampling days except at 5 and 25mg/kg dose-levels on day 70, but with severe oligospermia on days 28 and 35 (P<0.05-0.001). The sperm motility was decreased at 100mg/kg on days 14 and 21, at 5, 25, and 100mg/kg on day 28, and at all dose-levels on day 35 (P<0.05-0.001). Dacarbazine induced both head and tail abnormalities and some sperms with cytoplasmic droplets, but significant increase was seen in all dose groups on days 14 and 21, and at 100mg/kg dose-level on day 35. Drug-induced epithelial sloughing was seen on days 14-35 and other histopathological changes observed were vacuoles and abnormal cells. The STD was increased at 25-100mg/kg on day 7, at all dose-levels on day 14, at 50-100mg/kg on days 21 and 28, but without any effects on days 35-70 (P<0.05-0.001), and the tubular lumen was found dilated. The SE was increased on days 7, 21 and 28 at 100mg/kg and on day 14 at 50-100mg/kg. Dacarbazine reduced the intra-testicular testosterone level at 100mg/kg on day 7, at 5, 50 and 100mg/kg on day 14, at all dose-levels on days 21, 28, and 35, and at 50mg/kg on day 49 (P<0.05-0.001). The intra-testicular lactate dehydrogenase concentration increased at all dose-levels up to day 35, but without any effect on days 49 and 70 (P<0.05-0.001). There was no particular dose-response of dacarbazine on any parameters tested. The sperm count (except on day 7-positive correlation; Pearson product moment correlation) or sperm motility did not have any relation but increase in abnormal sperms showed negative correlation with decrease in testosterone level on days 7, 21 and 28. Decrease in sperm count was in negative correlation on days 14 and 35, and increase in abnormal sperms showed positive correlation on day 35 with increase in LDH level. Finally, the decrease in sperm motility had no correlation with increase in abnormal sperm shapes. We conclude that dacarbazine is genotoxic and cytotoxic to the mouse testis in a transient fashion, and these effects are exerted along with decrease in testosterone and increase in lactate dehydrogenase levels in the testis.     

Use of a Taqman PCR to determine the response of Mycoplasma haemofelis infection to antibiotic treatment

A quantitative Taqman polymerase chain reaction (PCR) assay was used to evaluate the response of Mycoplasma haemofelis experimentally infected cats to three antibiotic treatment regimes. Sixteen cats were intravenously inoculated with M. haemofelis from a chronically infected donor. The cats were randomly assigned to one of four treatment groups each containing four cats: oral doxycycline at 10 mg/kg/day for 14 days, oral enrofloxacin at 5 mg/kg/day for 14 days, oral enrofloxacin at 10 mg/kg/day for 14 days, and an untreated control group. DNA, extracted from blood samples collected on days 0, 7, 14, 21, 25, 28, 32, 35, 42 and 54 post-inoculation (PI), was subjected to quantitative Taqman PCR. The M. haemofelis copy number was significantly lower in the doxycycline group (P=0.008), the 5 mg/kg/day enrofloxacin group (P=0.006) and the 10 mg/kg/day enrofloxacin group (P=0.005) compared to the untreated control group. No significant differences were found between any of the three antibiotic treated treatment groups. All three antibiotic treatment regimes evaluated in this study were effective at reducing M. haemofelis copy number.     

Effect of age at weaning on the physiological stress response and temperament of two beef cattle breeds

The study was conducted to evaluate the effect of age at weaning and breed on the stress response of calves to weaning and their temperament. At calving, 14 Parda de Montaña calves and 14 Pirenaica calves were randomly assigned to either early weaning (at 90 days) or traditional weaning (at 150 days) treatment. During nursing, calves were allowed to suckle their dams twice a day for 30 min. After weaning, calves were placed in an adjacent barn without access to their dams, where they remained for 7 days. On day 8 after weaning, they were transported to a feedlot where they received an intensive diet. Blood samples were taken 168 h before weaning (baseline) and 6, 24, 48 and 168 h after weaning for cortisol, fibrinogen and haematology analyses, and temperament was measured 90 and 180 days after weaning with the flight speed test. Cortisol concentration increased after weaning, irrespective of age at weaning. Early-weaned calves had a lower fibrinogen baseline and a greater increase in fibrinogen concentrations 48 h after weaning than traditionally weaned calves. Moreover, fibrinogen concentration returned to baseline values 168 h after weaning in traditionally weaned calves, whereas it remained high in early-weaned calves. Concerning breed effects, Pirenaica calves had higher cortisol concentration and fibrinogen increments after weaning than Parda de Montaña calves. Slight alterations occurred after weaning in haematology, but all parameters returned to baseline values 168 h after weaning, with no significant effects of age at weaning or breed. Despite the absence of clinical signs, early-weaned calves of both breeds suffered marginal anaemia, according to haemoglobin values. Regardless of age at weaning, Pirenaica calves had greater reactivity to human presence than Parda de Montaña calves, according to their higher flight speed values measured. Finally, early-weaned calves were lighter than traditionally weaned calves at weaning, but had similar weight gains in the feedlot. Consequently, they needed an additional 40 days to reach the target weight, irrespective of breed. Therefore, age at weaning had no major effects on the stress response to weaning or temperament, but early weaning increased the length of the feedlot period. On the other hand, Pirenaica calves were more reactive than Parda de Montaña calves to the stress of weaning and human presence.     

Short communication: Manipulation of neonatal leptin profile via exogenous glucocorticoids in beef calves

The link between circulating glucocorticoids and leptin in beef calves has not been explored but has been noted in several studies. The aim of this study is to determine the effects of exogenous glucocorticoids given at birth and 1 day of age on serum leptin concentrations in beef calves. Ruminant animals secrete leptin, which is thought to be important for the programming of the hypothalamic appetite centers. Angus crossbred cows (n = 31) bred via natural service were utilized for this experiment. At parturition (day 0), calf BW was recorded and each calf was infused intravenously with either a hydrocortisol sodium succinate solution (HC, 8 males and 8 females) at a dosage of 3.5 μg/kg of BW or a similar volume of saline solution (CONT, 7 males and 8 females). Each calf was given a second infusion of its respective treatment 24 h postpartum at 1.5 μg/kg of BW for HC treatment. Calf treatment was blocked by sex, dam body condition score (BCS), and dam age. Blood samples were taken via jugular venipuncture before infusion, daily from days 0 to 5, then every other day up to day 17. Serum leptin and cortisol concentrations were analyzed via radioimmunoassay. Dam age, dam BCS, calf BW, and serum leptin and cortisol concentrations were analyzed using MIXED procedure of SAS. Dam age was not different (P = 0.81) among HC and CONT calves (4.9±0.5 and 4.7±0.5, respectively). Dam BCS was not different between treatments (5.7±0.2 and 5.6±0.2 HC and CONT, respectively; P = 0.66). There was no difference in calf birth BW between treatments (P = 0.87) and averaged 38.3±1.4 kg. Cortisol concentrations were not different between both treatments (P = 0.23) from birth to day 4 of age. Calves that received the HC treatment showed significantly reduced (P = 0.03) leptin concentrations on days 1 to 13. Calf BW from 60 to 150 days of age was not different between CONT and HC treated calves (P = 0.65). These data indicate that exogenous glucocorticoids can be used to suppress neonatal leptin levels in calves. This could lead to changes in voluntary feed intake of treated calves.     

Attempted Passive Immunization of Young Calves Against Eimeria bovis

SYNOPSIS. Two experiments attempted to produce passive immunity against Eimeria bovis coccidiosis in Holstein-Friesian calves. Immune serum concentrated by a freezing technique, or serum globulin obtained by a precipitating technique from immune calves, was injected intravenously or intraperitoneally into young calves. Four calves received concentrated immune serum injected intravenously on the day of oral inoculation with sporulated oocysts and again 7 and 14 days later. Four calves were given intravenous injections with some of the same serum on the 7th and 14th days after inoculation and 4 others were given a single similar injection with the same serum 14 days after inoculation.
Three calves in a second experiment received intraperitoneal injections of serum globulins in increasing amounts every 3 days for 2 weeks. The calves were then orally inoculated with sporulated oocysts one week after the last globulin injection. Some calves receiving immune serum had an anaphylactoid reaction characterized by increased respiration rate, dyspnea, coughing, and salivation; however, all affected calves recovered spontaneously within 2 hours. Calves receiving serum globulin had no reactions.
Coccidiosis developed in all of the calves in spite of the injection of immune serum or globulin presumed to carry the immune factor. There was no detectable difference in the rate of oocyst discharge or in clinical symptoms between treated and control calves; therefore, no evidence of passive immunity was observed.     

Influence of level of nutrition during late pregnancy on reproductive productivity of red deer I. Adult and primiparous hinds gestating red deer calves

The present study aimed to relate feed intake of red deer hinds during late pregnancy to dam body condition, foetal development and calf growth. Across 3 years, multiparous (n=33) or primiparous (n=18) hinds with known conception dates were housed in individual pens from days 150-220 of pregnancy, during which time they were each offered one of three daily allowances of pelletised rations (11 MJME/kg DM; 16% CP): high (H; ad libitum), medium (M; approximately 30% less; multiparous hinds only) and low (L; approximately 50% less). Restricted intake levels were retrospectively calculated from the mean intake of H hinds in the previous week. Hinds were returned to pasture at day 220 and calving was closely monitored. Liveweights, body condition score (BCS), and lactation score (LS) of hinds were recorded weekly from day 130 of pregnancy until calves were weaned at 12 weeks of age. Calves were tagged and weighed at birth, and subsequently weighed at 7 and 12 weeks of age. Additionally, hinds in the first year of study underwent CT scans on days 150 and 215 of pregnancy to assess compositional changes of the dam and conceptus. Mean daily ad libitum intakes of H hinds increased from 1.8 to 2.0 kg DM (0.6-0.7 MJME/kg0.75) at around day 150 to 2.8-3.2 kg DM (0.8-0.9 MJME/kg0.75) by day 220. Those of M and L hinds peaked at 1.8 and 1.6 kg DM, respectively, by day 220. This was reflected in significant treatment effects on liveweight gain and change in BCS and LS by the time of calving. CT scans indicated a significant treatment effect by day 215 on the mass of hind tissues (fat and lean) and a non-significant trend on conceptus/foetal weights. Despite apparent differences in foetal growth trajectories, there were no discernable treatment effects on sex-adjusted birth weights. However, there was an unexpectedly wide spread in calving dates that reflected considerable variation in gestation length. Furthermore, gestation length was negatively correlated with change in hind liveweight (but not BCS) between days 150 and 220 of pregnancy for all groups of hinds (P<0.05). Of three neonatal calf mortalities, none were related to overweight (dystocia) or underweight (non-viability) calves. Subsequent growth rates (g/day) of surviving calves did not reflect prior treatment of their dams, although variation in birth date influenced weights on specific dates. It is concluded from this study that while variation in nutrition to hinds during the last trimester may strongly influence foetal development, under conditions of modest feed imbalance, variation in gestation length compensates to ensure optimisation of birth weight.