Effects of imprint training procedure at birth on the reactions of foals at age six months

REASONS FOR PERFORMING STUDY: While imprint training procedures have been promoted in popular magazines, they have received limited scientific investigation. OBJECTIVES: To determine the effects of a neonatal imprint training procedure on 6-month-old foals and to determine if any one session had a greater effect than others. METHODS: Foals (n = 131) were divided into the following treatments: no imprint training, imprint training at birth, 12, 24 and 48 h after birth or imprint training only at birth, 12, 24, 48, or 72 h after birth. Foals then received minimal human handling until they were tested at 6 months. RESULTS: During training, time to complete exposure to the stimulus was significant for only 2 of 6 stimuli. Percentage change in baseline heart rate was significant for only 2 of 10 stimuli. These 4 effects were randomly spread across treatments. CONCLUSIONS: Neither the number of imprint training sessions (0, 1, or 4) nor the timing of imprint training sessions (none, birth, 12, 24, 48, or 72 h after birth) influenced the foal's behaviour at 6 months of age. POTENTIAL CLINICAL RELEVANCE: In this study, imprint training did not result in better behaved, less reactive foals.     

3周龄与6周龄断奶仔猪生产性能的比较

选9窝约长北3元杂交仔猪(116头)随机分成3组、第1、2组3周龄断奶,分别饲喂试验日粮和代乳料日粮。第3组6周龄断奶作为对照。6周龄到20公斤体重阶段饲喂同一营养水平的仔猪料,以比较3者的生产性能。试验结果表明:21—42日龄阶段,由于断奶应激,试验组日增重(ADG)明显低于对照组。42日龄以后至达20公斤体重阶段试验组的日增 重与对照组和代乳料组已无明显差异。早期断奶仔猪在度过断奶应激后,有补偿生长反应。     

Physiological responses in foals weaned by abrupt or gradual methods

Physiological responses to weaning procedures were studied in 21 foals assigned to one of five treatments: (1) abrupt, total separation of mare and foal, no preweaning creep feed (TSNC); abrupt, total separation with preweaning creep feed (TSC); partial separation of mare and foal allowing fenceline contact, no preweaning creep feed (PSNC); (4) partial separation with creep feed (PSC); and (5) control (CON) no separation of mare and foal, foals creep fed. Changes in adrenal response to exogenous ACTH, basal and peak plasma cortisol concentrations, plasma triiodothyronine (T3) and thyroxine (T4) concentrations, weight gains and feed consumption were measured. Foals on the total separation treatments had higher adrenal responses (P<.05) and pre-ACTH basal (P<.05) and post-ACTH peak plasma cortisol concentrations (P<.05) than foals on other treatments indicating they were stressed at weaning. The PSNC, PSC and CON treatments did not differ (P>.05) in any cortisol response. No treatment differences were found in thyroid hormone concentrations in this study. On partial separation treatments, creep-fed and non-creep-fed foals consumed similar amounts of feed during the first week postweaning. On total separation treatments, non-creep-fed foals consumed more feed (P<.05) than creep-fed foals. All foals without creep feed gained more weight immediately after weaning (0–2 weeks) than creep-fed foals (P<.05), reflecting higher feed intakes and possible compensatory gains. Total postweaning weight gains (0–8 weeks) of foals were not significantly affected by treatment.     

Gentamicin dosage in foals aged one month and three months

The absorption and disposition kinetics of gentamicin were compared at two dosage levels (2 and 4 mg/kg bodyweight [bwt]) in one- and three-month-old foals. Following intramuscular (im) injection of single 2 mg/kg bwt doses, the drug was absorbed rapidly and produced peak serum concentration (18.2 mu 5.3 +/- g/ml, n = 8) at 30 mins. Much wider variations were associated with the amount of drug absorbed and the serum gentamicin concentrations after administration at the higher dosage level. The half-life of gentamicin was similar in the one-month-old (3.7 +/- 1.7 h, n = 8) and three-month-old (3.3 +/- 0.8 h, n = 8) foals, and was independent of the dose. One-month-old foals did not appear to have a deficiency in renal excretion of gentamicin. The minimum inhibitory concentration of gentamicin for Corynebacterium equi and certain other equine bacterial isolates was less than 0.195 microgram/ml. It was concluded that 2 mg/kg bwt administered by im injection at 8 to 12 h intervals, depending on the severity of the infection, could be recommended as the dose rate for treatment of systemic infections caused by microorganisms that are susceptible to gentamicin.     

Longevity of breeding sows in relation to leg weakness symptoms at six months of age

The objective of this study was to evaluate the influence of leg weakness symptoms measured early in life (at 6 months of age) on the longevity of the sows, i.e. the age at culling due to locomotory problems in a Danish pig herd. One hundred and eighty-seven gilts at 6 months of age were selected according to different leg weakness symptoms and were followed until culling and judged for leg weakness once in every gestation using a scale from 1 (normal) to 4 (severe changes). Age at culling, and the main and secondary reasons for culling were recorded. The influence of leg weakness symptoms on longevity was evaluated by survival analysis. Though only 12% of the gilts showed a stiff locomotion half of the sows had suffered from this and nearly one third had been distinctly lame at some time in their life. Buck-kneed forelegs, upright pasterns, legs turned out, standing under position and swaying hindquarters were associated with stiff locomotion or lameness, whereas weak pasterns on hind legs and splayed digits on forelegs were associated with brisk movement (freedom from locomotor problems). The following leg weakness symptoms at the gilt stage were found to have significant negative effects on longevity: buck-kneed forelegs, swaying hindquarters, and standing under position on hind legs.     

Microcytosis, hypoferremia, hypoferritemia, and hypertransferrinemia in standardbred foals from birth to 4 months of age

At birth, 24 Standardbred foals were assigned at random to 1 of 2 groups and were given a placebo supplement (group 1) or an iron supplement (248 mg of iron/treatment; group 2). Foals were given iron supplement or placebo 4 times during the second and third weeks after birth. Hematologic variables and general health were monitored until foals were 4 months old. Mean PCV in foals of both groups decreased during the first 2 weeks after birth, but values remained within adult horse reference ranges. During the first 6 weeks after birth, foal erythrocytes were smaller than adult horse erythrocytes, but foal erythrocyte glucose-6-phosphate dehydrogenase activity was greater than that in adult horses. At every measurement, indices of anisocytosis were lower in foals, compared with adult horse reference values, suggesting that foals have a homogeneous population of microcytic erythrocytes during early foalhood. In 2-week-old foals of both groups and in 4-week-old placebo-treated foals, mean serum iron concentration was lower than that in adult horses. In foals at birth and during the first 4 months, total iron-binding capacity values were above the adult reference range. In newborn foals, transferrin saturation percentage values decreased to below the reference range in foals from 2 weeks to 4 months after birth. When foals were born, serum ferritin concentration values were above the adult horse reference range, but decreased to within the reference range by the time foals were 1 day old. From 2 through 6 weeks after birth, foal ferritin concentration values were below the adult reference range.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma vasopressin concentrations in healthy foals from birth to 3 months of age

Background: Arginine vasopressin (AVP) has received increased attention in equine critical care but there is minimal information of AVP concentration in foals. The clinical usefulness of measuring AVP in ill foals depends on knowledge of age-related changes in AVP concentrations in healthy foals.
Hypothesis: Plasma AVP concentrations will be significantly different when measured from birth to 3 months of age in healthy foals.
Animals: Thirteen healthy university-owned foals.
Methods: Prospective, observational study. Blood was collected from healthy foals at birth and 3, 5, 7, 10, 14, 21, 28, 42, 56, and 84 days of age. Plasma was harvested and plasma AVP concentrations were determined by radioimmunoassay.
Results: No statistically significant differences were detected in plasma AVP concentrations over the study period. Plasma AVP concentrations over the entire study period was 6.2 ± 2.5 pg/mL.
Conclusions and Clinical Importance: There was no age-related variation in plasma AVP concentrations detected in healthy foals from birth to 3 months of age suggesting that AVP concentrations are similar across foals of these ages.     

Finishing cattle at pasture at 30 months of age or indoors at 25 months of age: Effects on selected carcass and meat quality characteristics

To examine the effect of a modification of a typically Irish dairy calf-to-beef production system, Charolais × Friesian steers were offered a finishing ration of grass silage ad libitum and 5.6 kg concentrates daily for 174 days prior to slaughter at 25 months of age or grass silage ad libitum for 174 days, followed by pasture for 167 days and slaughter at 30 months of age. Finishing at pasture increased carcass weight (376 vs. 342 kg) but did not affect intra-muscular lipid concentration (28 vs. 24 g/kg). Finishing at pasture decreased Longissimus thoracis et lumborum lightness (35.6 vs. 36.9) and increased shear force of muscle at 2 (8.54 vs 4.32) and 7 days (5.21 vs 3.64 kg) post-mortem but not at 14 days post-mortem (4.45 vs. 3.42 kg). Finishing at pasture did not affect the sensory characteristics of tenderness, juiciness, firmness or chewiness and tended (P < 0.1) to decrease texture and acceptability. It is concluded that modification of this beef production system as described, had minor effects on beef quality which are unlikely to be of commercial significance.     

Growth and plasma metabolites of lambs weaned to legume pasture at 28 days of age

Two trials evaluated the potential for weaning lambs directly onto legume pasture at 28 d of age. Ewes and their twin-reared lambs were placed in paddocks on d 19; ewes were removed on d 28. In Trial 1, 60 lambs were allocated to three treatments: unweaned controls (CON1), lambs weaned onto first-cut alfalfa either without supplementary grain (WOG) or with up to 270 g.hd-1.d-1 supplementary grain (WG). Daily gains for the CON1, WOG and WG lambs were 309, 118 and 159 g for the period from d 28 to 40 (P greater than .05) and 241, 195 and 245 g for the period from d 40 to 56 (P greater than .05), respectively. In Trial 2, 80 lambs were allocated to four treatments: weaning onto first-cut alfalfa (early alfalfa, EA), second-cut alfalfa (late alfalfa, LA) birdsfoot trefoil (BFT) and unweaned controls (CON2, pastured on second-cut alfalfa). Daily gains for CON2 lambs were greater (P less than .05) than gains of EA and LA lambs (327 vs 136 and 136 g, respectively) for d 28 to 40, but not different (P greater than .05) for d 40 to 56 (245, 227 and 195 g, respectively). Gains for BFT lambs were lower (P less than .05) than for CON2 lambs for both periods (122 and 136 g, respectively), and BFT lambs appeared to be unthrifty after weaning. By d 32, weaning caused plasma glucose to decline 16.0 mg/dl and plasma nonesterified fatty acids to increase 365 mu eq/liter from preweaning levels. Hematocrit values ranged from 31 to 35% (Trial 1) and 25 to 29% (Trial 2), suggesting that the weaned lambs did not suffer from dehydration. Crossbred lambs can be weaned at 28 d of age directly onto first-cut or second-cut alfalfa.     

Hormonal profiles, behavioral responses, and short-term growth performance after castration of pigs at three, six, nine, or twelve days of age

The objective of this study was to determine the effects of castration on short-term growth performance, hormone profiles, and behavior in pigs at 3, 6, 9, or 12 d of age. Ninety intact male pigs were assigned randomly to a treatment age by litter [3, 6, 9, or 12 d of age; n = 9 to 13 pigs per treatment (age) group]. Pigs within a single litter were then assigned to noncastrated (NC) or castrated (CAS) treatment groups according to BW. Pigs were nonsurgically fitted with jugular catheters, and blood samples were drawn immediately before castration (0 h) and at 0.5, 1, 1.5, 2, 24, and 48 h after castration. Body weights were obtained when pigs were catheterized and again at 24 and 48 h after castration. Serum samples were analyzed for cortisol, porcine corticosteroid-binding globulin, and dehydroepiandrosterone sulfate (DHEA-S). No differences were detected in initial BW of pigs, and there was no overall treatment effect on growth performance of pigs at 24 or 48 h posttreatment. A time x treatment interaction was detected (P < 0.01) for serum cortisol concentrations, such that cortisol was greater in CAS pigs than in NC pigs. No overall effect of age at castration was observed on cortisol concentrations. At 24 h after castration, serum cortisol concentrations returned to baseline in all treatment groups; however, at 48 h after castration, overall cortisol concentrations were elevated (P < 0.01) in the 6-, 9-, and 12-d-old pigs in both the CAS and NC groups compared with baseline concentrations. Total cortisol and porcine corticosteroid-binding globulin were used to calculate the free cortisol index (FCI). A time x treatment interaction was observed (P < 0.01) for FCI, such that FCI was greater in CAS males than in NC males. The FCI was also affected by age (P < 0.01). There was a time x treatment x age interaction (P < 0.01) for serum DHEA-S, such that DHEA-S concentrations decreased in CAS animals but increased in NC animals, and DHEA-S concentrations increased with age. During the first 2 h after castration, there was an overall age effect (P = 0.01) on the time that pigs spent standing, such that 3-d-old pigs stood more than 6-, 9-, or 12-d-old pigs. Treatment did not influence the time that pigs spent nursing, lying, standing, or sitting, although there was a trend (P = 0.08) for CAS pigs to be less active than NC pigs. These data indicate that castration is stressful regardless of age; however, the stress associated with handling seems to increase as pigs age.     

Haematological and blood biochemical characteristics of Dutch warmblood foals managed under three different rearing conditions from birth to 5 months of age

Reference values for haematological and blood biochemical variables may vary per breed and are influenced by age and, to a certain extent, by rearing conditions. To investigate the influence of age and rearing conditions, these variables were measured in Dutch Warmblood foals from birth to 5 months of age. The foals were divided into three groups with different exercise regimens: 14 foals got boxrest with no exercise; 14 foals were kept in comparable boxes, but received daily exercise; and 15 foals were maintained on pasture with free exercise. Blood samples were collected each month and 36 haematological and biochemical variables were measured. The influence of age and rearing conditions was statistically evaluated. Significant age effects were found for all variables with the exception of band-shaped leucocytes, eosinophilic leucocytes, basophilic leucocytes, monocytes, platelets, pCO2, and sodium, potassium, calcium, magnesium, creatinine and creatine phosphokinase levels. Rearing conditions appeared to influence the haemoglobin, packed cell volume, pH, base excess, bicarbonate, chloride, urea, and alkaline phosphatase values. Most age-related differences can be explained by growth and differentiation-related processes that are specific for young animals. Differences due to the different rearing conditions can partly be explained by the higher metabolism and greater maturation of tissues in foals maintained on pasture with free exercise. Some other differences were minor and were probably of no clinical relevance. The conclusion is that haematological and blood biochemical variables in the Dutch Warmblood foal mainly depend on age, thus warranting the use of specific age-related reference values for foals of this breed.     

Occurrence of coccidiosis in calves at one to six months of age, which are housed in a large capacity barn]

One- to six-month-old calves, housed in the large-capacity calf house of the Nová Bystrice state farm in the district of Jindrich?v Hradec were studied for the occurrence of coccidia in the period from January 1974 to April 1975. The coccidia found in these animals included nine species of the genus Eimeria: E. zuernii, E. bovis, E. ellipsoidalis, E. subspherica, E. auburnensis. The species E. alabamensis, E. cylindrica, E. wyomingensis and E. bukidnonensis occurred just sporadically. Further, the findings included oocysts of Isopora spp. The oocysts of the coccidia E. wyomingensis and Isopora spp. were found for the first time in Czechoslovakia. The overall extensity of invasion (EI) and intensity of invasion (II) grow with age as follows: (chart: see text) The results suggest that even modern large-capacity calf houses are not free from invasion by coccidia; the calves in the house under study were invaded by ten species. Transition to vegetable feeding is accompanied by a marked rise of the EI of all the species of coccidia found in the animals.     

Botulism in foals less than 6 months of age: 30 cases (1989-2002)

Botulism has been recognized as a clinical entity in foals since the 1960s. Also known as "Shaker foal" disease, the toxicoinfectious form of botulism affects foals, with the highest incidence in the United States seen in Kentucky and the mid-Atlantic region. The disease is characterized by progressive muscular weakness caused by the action of botulism neurotoxin at cholinergic neuromuscular junctions. Increased number of episodes and duration of recumbency, muscular trembling, and dysphagia are seen in affected foals. Left untreated, the disease can be rapidly fatal, with death occuring secondary to respiratory muscle paralysis within 24 to 72 hours of the onset of clinical signs. Very mildly affected foals can survive with minimal treatment Despite advances made in treatment of these foals, including administration of botulism antitoxin early in the course of the disease, there is still an impression that the disease carries a high mortality rate. The purpose of this study was to evaluate outcome in 30 foals <6 months of age diagnosed with botulism between 1989 and 2002 at the George D. Widener Large Animal Hospital, New Bolton Center. Two foals were euthanized for economic reasons early in the disease course, and I died while being treated. Survival of treated cases was greater than 96%. Approximately 50% of the cases required oxygen therapy, whereas 30% required mechanical ventilation. All foals, excepting 1 mildly affected foal, received botulism antitoxin. Mean duration of hospitalization was 14 days. With appropriate treatment, foals with botulism have a high survival rate.     

Rupture of the gastrocnemius muscle in six foals

Rupture of the gastrocnemius muscle and subsequent disruption of the reciprocal mechanism of the hind limb was diagnosed in 6 foals examined at 7 hours to 3 weeks of age. In 2 foals, the musculoskeletal injury was detected as an ancillary finding to clinical signs of neurologic dysfunction ascribed to hypoxic ischemic insult during delivery, whereas in the other 4 foals, musculoskeletal injury, manifested as inability to rise or stand unsupported, was the chief complaint at admission. Five foals had a history of dystocia and assisted delivery. Common clinical signs were inability to rise, disruption of the reciprocal mechanism, swelling in the caudal aspect of the thigh, instability of the stifle joint, and stifle joint effusion. For mild gastrocnemius injury, exercise restriction via forced recumbency, with minimal or no bandaging, may be sufficient treatment. For more severe disruption of the muscle, limb stabilization via splinting and intensive nursing and monitoring are necessary. Four foals had important concurrent problems, including musculoskeletal deformations (joint contractures), hypoxic ischemic disease, and failure of passive transfer and associated problems (ie, sepsis, polyarthritis, and pneumonia). Moderate to severe gastrocnemius muscle injury is difficult to treat successfully, and the long-term prognosis for athletic function should be regarded as guarded.     

Effect of age on the concentrations of amino acids in the plasma of healthy foals

The concentrations of 23 amino acids in the plasma of 13 healthy foals were determined before suckling, when foals were 1 to 2 days old, 5 to 7 days old, 12 to 14 days old, and 26 to 28 days old. The ratio of the branched chain amino acids to the aromatic amino acids was also calculated at the 5 time points. Analysis of the concentrations at the 5 ages revealed a significant temporal relationship for each amino acid ranging from a polynomial order of 1 to 4 inclusively. There were significant differences between several concentrations of amino acids in plasma at specific sample times; however, no consistent patterns were revealed. The concentrations of amino acids in healthy foals were markedly different from previously determined values in adult horses. The significant differences in the concentrations of amino acids in plasma of healthy foals at the 5 ages may represent developmental aspects of amino acid metabolism or nutrition.     

6月龄和成年牦牛卵巢及卵泡发育状况研究

为了研究6月龄牦牛和成年牦牛卵巢及表面卵泡发育状况,试验比较了6月龄和成年牦牛卵巢长度、宽度、厚度、重量、卵泡数量以及卵母细胞体外成熟培养效果。结果表明:成年牦牛卵巢长度(2.29±0.43)cm、宽度(1.91±1.31)cm和厚度(1.60±1.90)cm均显著大于6月龄牦牛[(1.65±0.30)cm、(1.14±0.25)cm、(0.79±0.26)cm](P<0.05),成年牦牛卵巢体积(6.92±7.00)cm3和重量(3.19±1.58)g极显著大于6月龄牦牛体积(1.63±0.93)cm3和重量(0.87±0.44)g(P<0.01)。6月龄牦牛Ⅰ级卵泡数(14.47±8.74)枚和平均总卵泡数(15.17±8.87)枚极显著高于成年牦牛Ⅰ级卵泡数(7.97±3.72)枚和平均总卵泡数(8.98±3.87)枚(P<0.01),Ⅱ级卵泡数差异不显著(P>0.05),成年牦牛平均每头含(0.02±0.15)枚Ⅲ级卵泡,而6月龄牦牛无Ⅲ级卵泡。成年牦牛有黄体卵巢重量显著大于无黄体卵巢重量(P<0.05),有黄体卵巢含(0.06±0.24)枚Ⅲ级卵泡,而无黄体卵巢不含Ⅲ级卵泡。6月龄和成年牦牛A、B级卵母细胞体外培养成熟率分别为(81.39±3.53)%、(80.44±4.50)%,差异不显著(P>0.05),而6月龄牦牛卵巢的平均卵母细胞数和平均A、B级卵母细胞数均显著高于成年牦牛(P<0.05)。