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1.
Holstein male calves were maintained on conventional (milk to 6 wk of age, fed grain and hay after weaning) and veal (milk replacer only) diets to 16 wk of age. Within each of these 2 physiological states (ruminating or non-ruminating), calves were fed low or high fat diets (ruminating: 3 and 10%; veal: 10 and 18%). Glucose tolerance tests were undertaken at 8 and 16 wk of age in each group. Basal concentrations (4 hr postfeeding) and areas under the response curves for plasma glucose and insulin were higher in veal calves (P < .0001). Ruminating calves fed higher fat utilized glucose more readily (smaller areas under the curves for both glucose and insulin, P < .10) than those fed lower fat. Age did not influence basal glucose concentrations (P > .10), but older calves had higher basal insulin (P < .0001) and greater areas under the curves (P < .0005) for both glucose and insulin after a glucose challenge. Rate of clearance (k) was greater in ruminating calves (P < .001). Though rate of clearance in veal calves was slower, larger plasma pool size caused veal calves on average to utilize glucose at a 15% greater rate per kg body weight than ruminating calves. Whereas fat concentration in the diets did not influence glucose metabolism in veal calves, the high lactose content (> 50% of diet dry matter) of veal diets induced severe insulin resistance in these calves.  相似文献   

2.
Metabolic adaptations to heat stress in growing cattle   总被引：1，自引：0，他引：1  
To differentiate between the effects of heat stress (HS) and decreased dry matter intake (DMI) on physiological and metabolic variables in growing beef cattle, we conducted an experiment in which a thermoneutral (TN) control group (n = 6) was pair fed (PF) to match nutrient intake with heat-stressed Holstein bull calves (n = 6). Bulls (4 to 5 mo old, 135 kg body weight [BW]) housed in climate-controlled chambers were subjected to 2 experimental periods (P): (1) TN (18 °C to 20 °C) and ad libitum intake for 9 d, and (2) HS (cyclical daily temperatures ranging from 29.4 °C to 40.0 °C) and ad libitum intake or PF (in TN conditions) for 9 d. During each period, blood was collected daily and all calves were subjected to an intravenous insulin tolerance test (ITT) on day 7 and a glucose tolerance test (GTT) on day 8. Heat stress reduced (12%) DMI and by design, PF calves had similar nutrient intake reductions. During P1, BW gain was similar between environments and averaged 1.25 kg/d, and both HS and PF reduced (P < 0.01) average daily gain (-0.09 kg/d) during P2. Compared to PF, HS decreased (P < 0.05) basal circulating glucose concentrations (7%) and tended (P < 0.07) to increase (30%) plasma insulin concentrations, but neither HS nor PF altered plasma nonesterified fatty acid concentrations. Although there were no treatment differences in P2, both HS and PF increased (P < 0.05) plasma urea nitrogen concentrations (75%) compared with P1. In contrast to P1, both HS and PF had increased (16%) glucose disposal, but compared with PF, HS calves had a greater (67%; P < 0.05) insulin response to the GTT. Neither period nor environment acutely affected insulin action, but during P2, calves in both environments tended (P = 0.11) to have a blunted overall glucose response to the ITT. Independent of reduced nutrient intake, HS alters post-absorptive carbohydrate (basal and stimulated) metabolism, characterized primarily by increased basal insulin concentrations and insulin response to a GTT. However, HS-induced reduction in feed intake appears to fully explain decreased average daily gain in Holstein bull calves.  相似文献   

3.
Thirty-six crossbred steers (288 +/- 3.7 kg initial BW) were used to determine the effect of Cr, as chromium-L-methionine, on glucose tolerance and insulin sensitivity in beef calves. Calves were fed a control diet or the diet supplemented with 400 or 800 microg Cr/kg of diet as chromium-L-methionine. Calves were kept in drylots (six calves/pen; two pens/dietary treatment). Steers were caught twice a day in locking headgates and individually fed their respective diets for a period of 22, 23, or 24 d prior to the metabolic challenges. Calves received a totally mixed diet containing 54% corn, 38% cottonseed hulls, and 5% soybean meal. On d 21, 22, and 23, four calves/dietary treatment were fitted with an indwelling jugular catheter. Approximately 24 h after catheterization, an intravenous glucose tolerance test (500 mg glucose/kg of BW), followed 5 h later by an intravenous insulin challenge test (0.1 IU insulin/kg of BW), was conducted. There was no effect (P > 0.10) of dietary treatment on ADG or ADFI. During the intravenous glucose tolerance test, serum insulin concentrations were increased by supplemental chromium-L-methionine (linear effect of Cr, P < 0.05). There was a time x treatment interaction (P < 0.05) on plasma glucose concentrations after the glucose infusion. Plasma glucose concentrations of calves fed 400 microg Cr/kg of diet were lower than those of controls and calves supplemented with 800 microg Cr/kg of diet (quadratic effect of Cr, P < 0.05) 5 and 10 min after the glucose infusion. Supplemental chromium-L-methionine increased the glucose clearance rate from 5 to 10 min after the insulin challenge test (linear effect of Cr, P < 0.05). Glucose half-life from 5 to 10 min after the insulin infusion was also decreased by supplemental chromium-L-methionine (linear effect of Cr, P < 0.10). These data indicate that supplemental Cr, as chromium-L-methionine, increased glucose clearance rate after an insulin infusion and increased the insulin response to an intravenous glucose challenge in growing calves with functioning rumens.  相似文献   

4.
This study aimed to determine the effects of feeding an increased volume of high‐fat milk during the early post‐natal life on metabolite concentrations in the blood, the expression of key genes regulating intermediary metabolism in the skeletal muscles, and the rate of growth of Japanese Black cattle. All calves were fed a high‐fat milk replacer (crude protein, 26%; crude fat, 25.5%; total dissolved nitrogen, 116%). Control calves (n = 4) were nursed with 500 g milk replacer until 3 months of age, whereas calves in the experimental group (n = 4) were nursed with 1800 g milk replacer until 3 months, and then the volume was gradually reduced until 5 months. Body weight was significantly higher in the experimental group than in the control group at 7 months. Plasma glucose concentrations were significantly lower in the experimental group. Expression of glucose‐transporter‐4 messenger RNA (mRNA) was lower, whereas that of glucose transporter 1, cluster of differentiation 36, and carnitine palmitoyltransferase‐1b mRNA was significantly higher in the Longissimus thoracis of the experimental group. Nutritional status during early post‐natal life appears to strongly influence the growth rate and glucose and lipid metabolism in Japanese Black cattle.  相似文献   

5.
Intestinal malabsorption or transferable resistance in enteric bacteria are potentially serious complications of routine oral administrations of antibiotics. On the basis of reports on antimicrobial effects of host iron sequestration and on synthetic iron chelators or competitors in vitro, 2 iron antagonists were studied for their potential as alternative antimicrobials for Escherichia coli diarrhea. Deferoxamine, a fungal iron chelator used to treat acute iron intoxication, and elemental gallium, a competitive inhibitor of iron activity in metabolic enzyme systems, were examined for their effects on enteric morphology and function in neonatal calves. Twelve male calves were allotted to 4 groups: (1) given nonpathogenic E coli (control); (2) given enterotoxigenic B44 E coli; (3) given deferoxamine (50 mg/kg, twice a day); and (4) given gallium (4 mg/kg, twice a day). Calves were studied for 8 days, including the conduct of oral glucose and lactose tolerance tests on days 1, 3, and 7. By day 7, according to oral glucose and lactose tolerance tests, peak plasma glucose concentrations in all calves of groups 2, 3, and 4 were lower than those values in controls. The frequency of diarrhea was significant in all treated calves, and disease was most severe in the deferoxamine-treated calves. Quantitative cultural examination on day 8 showed significant numerical increases of jejunal and ileal E coli and ileal lactobacilli in deferoxamine-treated calves (group 3) and of ileal streptococci in gallium-treated calves (group 4) and showed jejunal and ileal overgrowths of Saccharomyces yeast in deferoxamine-treated calves.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

6.
《动物营养（英文）》2021,7(4):1352-1359
The objective of this experiment was to investigate the potential benefits of active dry yeast (ADY) on the growth performance, rumen fermentation, nutrient digestibility, and serum parameters of weaned beef calves. Thirty Simmental crossbred male calves (body weight = 86.47 ± 4.41 kg and 70 ± 4 d of age) were randomly divided into 2 groups: control (CON) (fed basal ration) and ADY (fed basal ration and 5 g/d ADY per calf). The dietary concentrate-to-roughage ratio was 35:65. All the calves were regularly provided rations 3 times a day at 07:00, 13:00, and 19:00 and had free access to water. The experiment lasted for 60 d. The average daily gain of ADY group was higher (P = 0.007) than that of the CON group, and the ratio of feed intake to average daily gain in the ADY group was reduced (P = 0.022) as compared to the CON group. The concentration of ruminal ammonia-N was higher (P = 0.023) in the CON group than that in the ADY group, but an opposite trend of microbial protein was found between the 2 groups. Also, the ruminal concentrations of propionate and butyrate were higher (P < 0.05) in the ADY group than those in the CON group. Calves fed ADY exhibited higher (P < 0.05) crude protein and neutral detergent fiber digestibility. Supplementation of ADY increased (P < 0.05) the contents of glucose, glutathione peroxidase, superoxide dismutase, immunoglobulin A, immunoglobulin M, and interleukin 10 in the serum of calves, but an opposite trend was observed in malondialdehyde, interleukin 1 beta, and tumor necrosis factor alpha contents between the 2 groups. In conclusion, dietary supplementation with ADY could improve the growth performance, rumen fermentation, nutrient digestibility, antioxidant ability, and immune response of weaned beef calves.  相似文献   

7.
Influence of yeast culture on feeder calves and lambs.   总被引：4，自引：0，他引：4  
Four experiments were conducted to determine the influence of yeast culture on 1) the health and performance of feeder calves, 2) the response of calves to an infectious bovine rhinotracheitis virus (IBRV) infection, and 3) nutrient utilization in lambs fasted for 3 d. In Exp. 1, 108 feeder calves were transported from Tennessee to Texas (1,600 km) and fed receiving diets containing 0 or .75% yeast culture and .35 or .69% P in a 2 x 2 factorial arrangement of treatments. In Exp. 2, 101 calves were transported 950 kg from Austin, TX to Bushland, TX and fed receiving diets containing 0, .75, 1.125, or 1.5% yeast culture. Yeast culture did not significantly affect the health or performance of calves in either experiment, although morbid calves fed yeast culture required fewer (P less than .05) days of antibiotic therapy in Exp. 2. In Exp. 3, feeder steers were fed diets containing 0 or .75% yeast culture and challenged intranasally with IBRV. Calves fed yeast culture tended to maintain heavier weights and higher DMI during IBRV infection than did steers fed the control diet. In Exp. 4, feeder lambs were fasted for 3 d and refed diets containing 0, .75, 1.125, or 1.5% yeast culture during a N and mineral balance trial. Lambs fed yeast culture had greater (P less than .08) N balance and tended to have greater Zn and Fe balance than control lambs. Results of these studies are interpreted to suggest that supplementation of morbid calves with yeast culture can have beneficial effects (fewer sick days, higher feed intakes) and that these effects may be mediated by improved N, Zn, and Fe metabolism.  相似文献   

8.
AIM: To determine the welfare of calves arriving at a slaughter plant by assessing their physical state and plasma biochemical profile. METHODS: Calves (n=7,169) aged 4-10 days, were examined immediately after they were unloaded from trucks (n=20) and categorised on physical grounds as being in an 'unacceptable', 'marginal' or 'acceptable' state. 'Unacceptable' calves were lying down, unable to walk, extremely weak or seriously injured. 'Marginal' calves had a wet umbilicus, were hollow sided, apparently immature, or weak and slow and unsteady on their feet. 'Acceptable' calves were strong, walked freely, round-sided, bright and alert and had a dry umbilicus. After unloading, 27 'unacceptable', 306 'marginal' and 289 'acceptable' calves were weighed, examined clinically and a blood sample was taken from each. A second blood sample was taken from 118 of these calves, 12-15 hours later. The packed cell volume (PCV) and plasma concentrations of glucose, beta-hydroxybutyrate (BHB), total plasma proteins (TPP), gamma-glutamyl transferase (GGT), urea, creatine kinase (CK) and lactate were measured. RESULTS: Only 27 of the 7,169 calves examined (0.4%) were categorised as being in an 'unacceptable' state on arrival and these were euthanased shortly after unloading. Generally, the plasma biochemical profiles of the 'acceptable' calves were similar to those of 'marginal' animals. However the glucose concentration of 'marginal' calves was lower than that of 'acceptable' calves, suggesting that they had lower energy reserves. After 12-15 h in lairage, plasma glucose concentration decreased and the BHB concentration increased in both 'acceptable' and 'marginal' calves compared with concentrations measured on arrival. CONCLUSIONS: The percentage of calves presented for slaughter in an 'unacceptable' state was small (0.4%). However, 4% of calves were classified as 'marginal' and failed to meet all the requirements of the code of recommendations and minimum standards governing the welfare of young calves in New Zealand. The categorisation of calves by a physical assessment was supported by results of plasma biochemistry. As a result, plasma biochemical profiles are considered unnecessary for making decisions regarding the welfare status of calves arriving at a slaughter plant; an assessment of their physical state is sufficient.  相似文献   

9.
Crossbred steer calves (n = 64) were used in a 2 × 2 factorial arrangement to evaluate two levels of organic trace minerals and two levels of inorganic trace minerals. Calves were fed 28 d on the ranch in two pens of eight head per treatment before a simulated transport stress. After being loaded, hauled 129 km, unloaded with an overnight stand without feed and water, and reloaded, they were shipped to the Colorado State University (CSU) research feedyard in Fort Collins and placed in 64 individual pens. Calves fed the organic low level and inorganic high level trace minerals gained better (P<0.05) the first 28 d than did calves fed the organic high level or inorganic low level trace minerals. Overall growth performance was not influenced by trace mineral types or levels. Longissimus area was greater (P<0.05) for calves fed the low level organic trace minerals compared with that for calves fed the low level inorganic trace minerals. Eosinophils (d 28) were higher (P<0.05) for calves fed the organic high level trace minerals compared with calves fed inorganic low level trace minerals. Infectious bovine rhinotracheitis (IBR) and parainfluenza (PI3) titers were not influenced by trace minerals. Red blood cells and packed cell volume were higher (P<0.05) for calves fed low level trace minerals regardless of trace mineral type. Liver Co was increased (P<0.05) at the 28-d sampling when inorganic trace minerals were fed. Liver Co was highest (P<0.05) at the 168- d sampling for calves fed low level inorganic trace minerals followed by calves fed organic high level trace minerals. Liver Fe was lower (P<0.05) in calves at the d-168 sampling when organic trace minerals were fed. Liver Zn was elevated (P<0.05) by d 28 by feeding the inorganic low level trace minerals, and by d-168, liver Zn was higher (P<0.05) for calves fed the low levels of trace minerals. Initial growth performance was maintained by either supplementing organic trace minerals or elevating dietary inorganic trace minerals when confronted with high dietary Fe, S, or Mo.  相似文献   

10.
AIM: Using specified indices, to determine the nutritional and thermal status of calves between 1 and 4 days of age.

METHODS: After birth, calves (n=106) were collected daily, according to farm practice. Over the following 4 days a jugular blood sample and rectal temperature were taken twice daily before feeding. Plasma concentrations of glucose, beta-hydroxybutyrate and urea, and gamma-glutamyl transferase (GGT) activities were determined. The significance of differences in plasma composition and rectal temperature between calves whose birth had been assisted or unassisted, and between calves with low and high plasma GGT activities 24 h after birth, was determined using repeated measures analysis of varianc

RESULTS: There were no marked differences in plasma metabolite levels or body temperature of assisted and unassisted calves. Calves that had high plasma GGT activities 24 h after birth had higher plasma glucose concentrations over the 4 days than calves that had low plasma GGT activities (p<0.001). Overall, compared to published data on poorly-fed and hypothermic calves, calves in this study were normoglycaemic, their plasma beta-hydroxybutyrate and urea concentrations were low and their rectal temperatures were normal, indicating that they were well fed and did not become hypothermic.

CONCLUSIONS: The nutritional and thermal status of at least 90% of the calves was compatible with good health and survival during the first 4 days after birth.  相似文献   

11.
Two trials were conducted to investigate the effects of supplemental chromium (Cr) from organic sources (Cr chelate and high Cr yeast) on antibody responses of newly arrived feeder calves following vaccination with infectious bovine rhinotracheitis (IBR), para-influenza-3 (PI3), bovine respiratory syncytial virus (BRSV), bovine viral diarrhea (BVD) and Pasteurella haemolytica and ovalbumin (OVA). Using cross bred steer calves purchased at sales in Ontario, vaccines and OVA were given on d 0 and 21 after arrival in the feedlot. Immune responses of calves were measured as serum specific antibody titres against all antigens on d 0 and 28 or d 35. The anti-OVA antibody responses (trial 2) were further investigated by measuring antibody concentrations of calves weekly until d 55 after arrival in the feedlot. Supplemental Cr (0.14 ppm) from an amino acid-chelated source had no effect on antibody responses to IBR, P13 and BRSV, but enhanced (P < 0.05) antibody titres of calves in response to the BVD vaccine on d 28 or d 35. Supplemental Cr from Cr yeast had no effect on antibody titres of calves to any vaccines. Chromium from both sources (trial 1 and 2) had no effect on antibody responses of calves following vaccination with P. haemolytica. However, supplemental Cr (0.75 ppm) from Cr yeast enhanced (P < 0.05) serum antibody responses of calves to OVA during the primary response (d 14) and secondary response (d 35) following immunization. These data confirmed our previous finding that supplemental Cr can enhance humoral immune response of market-transit stressed calves, but its enhancement on vaccine efficacy was antigen-dependent and variable.  相似文献   

12.
AIM: Using specified indices, to determine the nutritional and thermal status of calves between 1 and 4 days of age. METHODS: After birth, calves (n=106) were collected daily, according to farm practice. Over the following 4 days a jugular blood sample and rectal temperature were taken twice daily before feeding. Plasma concentrations of glucose, beta-hydroxybutyrate and urea, and gamma-glutamyl transferase (GGT) activities were determined. The significance of differences in plasma composition and rectal temperature between calves whose birth had been assisted or unassisted, and between calves with low and high plasma GGT activities 24 h after birth, was determined using repeated measures analysis of variance. RESULTS: There were no marked differences in plasma metabolite levels or body temperature of assisted and unassisted calves. Calves that had high plasma GGT activities 24 h after birth had higher plasma glucose concentrations over the 4 days than calves that had low plasma GGT activities (p<0.001). Overall, compared to published data on poorly-fed and hypothermic calves, calves in this study were normoglycaemic, their plasma beta-hydroxybutyrate and urea concentrations were low and their rectal temperatures were normal, indicating that they were well fed and did not become hypothermic. CONCLUSIONS: The nutritional and thermal status of at least 90% of the calves was compatible with good health and survival during the first 4 days after birth.  相似文献   

13.
The purpose of this study was to investigate the potential benefits of yeast cell wall (YCW) on the gastrointestinal development of weaned calves. Twenty healthy Holstein male calves (BW = 92 ± 8.29 kg and 60 ± 5 d of age) were randomly allocated into 2 groups: CON with no YCW, and YCW (accounted for 0.16% of the basal diet). The dietary concentrate-to-roughage ratio was 40:60. All the calves were fed regularly twice a day at 09:00 and 16:00 and had free access to water. The experiment lasted for 60 d. The results showed that calves fed YCW showed higher (P < 0.05) length, width, and surface area of papillae in the ventral sac of the rumen as compared to CON. For the dorsal sac of the rumen, the muscularis thickness was thicker (P < 0.05) in the YCW group when compared with CON group. The villus height of YCW calves was higher (P < 0.05) than that of CON in the ileum. Calves supplemented with YCW also showed a higher (P < 0.05) villus height-to-crypt depth ratio in the ileum. The YCW calves exhibited a greater (P < 0.05) thickness of the wall in the duodenum and jejunum. Calves supplemented with YCW improved (P < 0.05) the claudin 1 mRNA expression in the ileum and occludin mRNA expression in the jejunum and ileum. The YCW increased (P < 0.05) the contents of secretory immunoglobulin A in the jejunum and ileum of calves. In conclusion, dietary supplementation with YCW could improve the gastrointestinal development of weaned calves.  相似文献   

14.
The current study was conducted to clarify the characteristics of glucose and urea kinetics in male Japanese Black calves, using a glucose and urea dilution method with stable isotopes, at preweaning (3 wk of age) and postweaning (13 and 26 wk of age) stages, in comparison with the kinetics of glucose and urea in male Holstein calves. Six Japanese Black and 6 Holstein calves were arranged in a 2 (breed) x 3 (stage) factorial block design. These 12 suckling calves were fed only whole milk, offered concentrate and or chardgrass hay after 3 wk of age, and weaned at 6 wk of age. Under steady-state conditions, glucose challenges (1.0 mg/kg of BW; [U-13C]d-glucose) and urea challenges (both 2.2 mg/kg of BW; [13C]urea and [15N2]urea) were performed at the 3 stages examined. There were no significant differences in plasma glucose concentrations between Japanese Black and Holstein calves at any stage, but the glucose concentrations at 3 wk of age were greater (P <0.05) than those at 13 wk of age in both breeds. The glucose pool size in Japanese Black calves was smaller (P <0.05) than that in Holstein calves at all stages. Within each breed, there were no significant differences between the glucose pool sizes at 3 and 13 wk of age, but the glucose pool size was larger (P <0.05) at 26 wk of age. Moreover, Japanese Black calves had greater glucose irreversible loss rates (P <0.01) than Holstein calves at 3 wk of age, and the glucose irreversible loss rates were less (P <0.05) on and after 13 wk of age in both breeds. Japanese Black calves had greater plasma urea N concentrations (P <0.05) than Holstein calves at all stages, and in both breeds, the urea N concentrations increased (P <0.05) with age. The urea pool size was smaller (P <0.01) in Japanese Black calves than in Holstein calves at all stages, and in both breeds, the urea pool size increased (P <0.05) with age. In comparison with Holstein calves, Japanese Black calves had greater urea irreversible loss rates (P <0.05) on and after 13 wk of age and greater urea recycling rates (P <0.05) at 26 wk of age. In addition, in both breeds, urea irreversible loss rates and urea recycling rates increased (P <0.05) with age. We conclude that Japanese Black calves have partially different glucose and urea kinetics from Holstein calves and that the kinetics of these metabolites in both Japanese Black and Holstein calves are strongly influenced by weaning.  相似文献   

15.
Samples of stomach contents from 150 calves on farms and in veal units were examined for the presence of Torulopsis glabrata yeast and ethanol. Ninety-one animals contained the yeast, and 94 ethanol. Out of 10 calves having in excess of 30 mg/100 ml ethanol and counts of more than 104/ml of yeasts in their rumens, 7 were receiving the only milk replacer demonstrably containing large amounts of carbohydrate fermentable by T. glabrata. Twelve animals also had Candida albicans in their rumens. A separate group of 14 calves, receiving one milk replacer not containing carbohydrate fermentable by T. glabrata, were similarly examined twice at a 7-day interval; 12 contained low levels of ethanol and small numbers of yeasts in their rumen contents.  相似文献   

16.
Effects of feeding pregnant dams supplemental dietary fat during the last 55 d of gestation on cold tolerance of newborn crossbred calves with (Piedmontese cross, P, n = 15) or without (Hereford cross, H, n = 16) the muscle hypertrophy allele was determined. Primiparous F1 dams gestating F2 calves of the respective breeds were assigned randomly within breed to receive gestation diets containing either 2.2 (Low Fat; LF) or 5.1% fat (High Fat; HF). Safflower (Carthamus tinctorius L.) seeds containing 37% oil with 79% linoleic acid were the supplemental fat source in diets formulated to be isocaloric-isonitrogenous. At parturition, calves were separated from their dams, fed 38 degrees C pooled dairy cow colostrum (30 mL/kg BW), muzzled to prevent suckling, and returned to their dams in a heated (22 degrees C) room for 3.5 h. At 4 h of age (birth = 0 h), a catheter was inserted into the jugular vein. At 5 h of age, calves were placed in a 0 degrees C room for 140 min, and rectal temperatures and blood samples were obtained at 10- and 20-min intervals. Blood was assayed for cortisol and glucose. Rectal temperature was affected by diet (P<.05), time, diet x time, and breed x time (P<.01 for time and the interactions). Cortisol and glucose concentrations were not affected by diet, breed, or the diet x breed interaction, but they were affected by time, breed x time (both P<.01), and diet x time (P = .06). Calves from HF dams had higher rectal temperatures than calves from LF dams, and the HF calves maintained higher rectal temperatures throughout cold exposure. Cortisol concentrations were lower (P = .06) in calves from HF dams, and these calves had more (P = .06) glucose available for metabolic heat production than calves from LF dams. Piedmontese-cross calves maintained higher (P<.01) rectal temperatures and had higher cortisol and glucose (both P<.01) concentrations than did H-cross calves. We conclude that feeding dams supplemental fat during late gestation increased heat production in newborn calves and potentially could increase calf survival; calves with muscle hypertrophy may have a different ratio of shivering vs nonshivering thermogenesis due to differences in body composition or relationships among uncoupling proteins.  相似文献   

17.
This study was completed to determine the prevalence and distribution of Toxocara vitulorum infection in cattle and buffalo calves and investigate its clinical impact in northern Lao PDR (Peoples Democratic Republic). The results aim to assist decisions on disease control measures that can contribute to increasing cattle and buffalo productivity within smallholder farming systems in tropical areas. A prevalence survey for T. vitulorum in buffalo and cattle calves aged <3 months was conducted between September 2009 and June 2010 in five provinces of northern Lao PDR using a two-stage sampling technique to select 69 villages and 899 calves, with faecal samples collected and examined for T. vitulorum eggs at a local laboratory. At the time of sampling, data on calf morbidity and anthelmintic treatment was also collected. Factors potentially associated with infection and severity of infection were analyzed at univariable and multivariable levels, using T. vitulorum status (positive/negative) and on the positive calves only, faecal egg count levels as outcome variables. The estimated prevalence of T. vitulorum in northern Lao was 22.6 % (95 % confidence interval [CI], 0.17–0.28), and 76.8 % of villages had at least one positive calf. Province was the only significant (p?<?0.05) variable investigated associated with calf infection status. Species (buffalo) was the only variable significantly (p?<?0.05) associated with higher egg per gram of faeces levels among infected calves. Prevalence in calves aged 1–21 days, the reported prepatent period, was 17.5 % (CI 0.11–0.24). Treatment levels were very low (8.2 %) and if treatment occurred it was mostly unsuccessful. The high and wide spread infection of T. vitulorum in cattle and buffalo calves identified in this survey is likely to result in suboptimal cattle and buffalo productivity. Improved management of T. vitulorum infection in cattle and buffalo calves in northern Lao PDR is indicated to reduce potential negative production impacts and enable more efficient development of large ruminant livestock industry as a pathway from rural poverty for smallholder farmers in northern Lao PDR. In addition to quantifying this disease problem in calves, the conduct of this applied participatory research study provided an important opportunity to improve animal health services by increasing the parasite, large ruminant handling and research knowledge and capacity of government animal health staff and farmers.  相似文献   

18.
Although substantial fecal shedding is expected to start years after initial infection with Mycobacterium avium subspecies paratuberculosis (MAP), the potential for shedding by calves and therefore calf-to-calf transmission is underestimated in current Johne’s disease (JD) control programs. Shedding patterns were determined in this study in experimentally infected calves. Fifty calves were challenged at 2 weeks or at 3, 6, 9 or 12 months of age (6 calves served as a control group). In each age group, 5 calves were inoculated with a low and 5 with a high dose of MAP. Fecal culture was performed monthly until necropsy at 17 months of age. Overall, 61% of inoculated calves, representing all age and dose groups, shed MAP in their feces at least once during the follow-up period. Although most calves shed sporadically, 4 calves in the 2-week and 3-month high dose groups shed at every sampling. In general, shedding peaked 2 months after inoculation. Calves inoculated at 2 weeks or 3 months with a high dose of MAP shed more frequently than those inoculated with a low dose. Calves shedding frequently had more culture-positive tissue locations and more severe gross and histological lesions at necropsy. In conclusion, calves inoculated up to 1 year of age shed MAP in their feces shortly after inoculation. Consequently, there is potential for MAP transfer between calves (especially if they are group housed) and therefore, JD control programs should consider young calves as a source of infection.  相似文献   

19.
Glucagon-like peptide-1 (7-36) amide (GLP-1), secreted by the small intestine, has insulinotropic and glucose-lowering action. Basal plasma GLP-1 concentrations were measured in calves around the weaning period, the effect of short-chain fatty acids (SCFA) on plasma GLP-1 concentrations was examined, and the effects of GLP-1 administration on plasma insulin, glucagon, and glucose concentrations were measured. Thirteen Holstein bull calves were fed whole milk and solid feed and weaned at 7 wk of age. Preprandial plasma samples were obtained from 5 calves once a week from week 0 to 13 to measure basal concentrations of plasma GLP-1 and insulin (experiment 1). Four calves were intravenously administered with a mixed solution of SCFA (2.4 mmol/kg body weight [BW]) in week 2 and 11 to measure plasma GLP-1 concentrations (experiment 2). Another 4 calves were intravenously injected with GLP-1 (1.0 μg/kg BW) to elucidate the response of plasma insulin, glucagon, and glucose concentrations in week 1, 2, 4, 6, 7, 9, 11, and 13 (experiment 3). In experiment 1, age and weaning did not affect preprandial basal concentrations of plasma GLP-1 throughout the experimental period. Preprandial insulin concentrations increased after weaning (P < 0.05), and GLP-1 and insulin were more strongly correlated postweaning than preweaning. In experiment 2, intravenous treatment with SCFA increased plasma GLP-1 concentrations in both week 2 and 11 (P < 0.05.) In experiment 3, intravenous GLP-1 treatment decreased plasma glucose concentrations throughout the experiment (P < 0.05), but increased plasma insulin concentrations only after weaning (P < 0.05). Treatment with GLP-1 did not affect plasma glucagon concentrations, regardless of age. These results indicate that preprandial basal concentrations of plasma GLP-1 in calves are not changed by weaning, but SCFA stimulate GLP-1 secretion. The insulinotropic action of GLP-1 is detected only after weaning, but the glucose-lowering action of GLP-1 is not affected by weaning.  相似文献   

20.
We investigated the effect of increasing nutrient intake on the responsiveness of the GH/IGF-I system in calves fed a high-protein milk replacer. Fifty-four Holstein bull calves were fed one of three levels (low, medium, and high; n = 18 per treatment) of a 30% crude protein, 20% fat milk replacer to achieve target rates of gain of 0.50, 0.95, or 1.40 kg/d, respectively, for low, medium, and high. Six calves per treatment were slaughtered at approximately 65, 85, and 105 kg BW. Additionally, six calves were slaughtered at 1 d of age to provide baseline data. Plasma aliquots from blood samples collected weekly were analyzed for IGF-I, insulin, glucose, NEFA, and plasma urea nitrogen (PUN). Plasma IGF-I and insulin, measured weekly, increased (P < 0.001) with greater nutrient intake from wk 2 of life to slaughter. Plasma glucose and NEFA also increased (P < 0.05) with nutrient intake. In addition, each calf underwent a GH challenge beginning 4 d before the scheduled slaughter. Plasma from blood collected before the first GH injection and 14 and 24 h after the third injection was analyzed for IGF-I and PUN. Response to challenge, calculated as the absolute difference between the prechallenge and 14-h postchallenge plasma IGF-I concentrations, was significant in calves on all three treatments. Plasma urea nitrogen was not different among treatments as measured weekly but decreased (P < 0.001) following GH challenge in all calves. Results of ribonuclease protection assays showed increased expression of hepatic mRNA for GH receptor 1A and IGF-I with increased intake. The amounts of GH receptor and IGF-I mRNA in muscle and adipose, however, were not affected by intake. In summary, plasma IGF-I was elevated in calves with increased nutrient intake, and the elevations in plasma IGF-I following short-term administration of GH were significant in all calves by 65 kg BW. Data demonstrate that in well-managed milk-fed calves the somatotropic (GH/IGF-I) axis is functionally coordinated and sensitive to nutrient intake and GH.  相似文献   

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