Metabolic response of horses to a high soluble carbohydrate diet: effects of low-intensity submaximal exercise and sodium bicarbonate supplementation.

Four mares fed a low fiber, high soluble carbohydrate diet were used in a crossover design to evaluate the effects of dietary sodium bicarbonate (NaHCO3) supplementation during daily low-intensity submaximal working conditions. Mares were fed the diet at 1.7 times the maintenance energy requirement for mature horses at work. The horses tolerated the diet well and had no clinical abnormalities. Resting venous blood bicarbonate (HCO3), standard HCO3, and base excess (BE) concentrations significantly (P less than 0.05) increased with NaHCO3 supplementation, but no significant changes in resting venous blood pH or carbon dioxide tension (PCO2) were recorded. Venous blood HCO3, standard HCO3, BE, hemoglobin, and heart rate were significantly (P less than 0.05) increased and plasma lactate concentration was significantly (P less than 0.05) decreased in the control horses and in the horses given the NaHCO3 supplement during low-intensity submaximal exercise. There were no significant changes in venous blood pH, PCO2, or plasma protein concentration with exercise. Venous blood HCO3, standard HCO3, and BE concentrations were significantly (P less than 0.05) greater during submaximal exercise in horses given the NaHCO3 supplement. There were no significant differences in plasma lactate or total protein concentrations, blood pH, PCO2, or hemoglobin concentration between the 2 groups during exercise.     

Immunization against cholecystokinin decreases appetite in lambs.

The effects of immunization against cholecystokinin (CCK) on feed intake, weight gain, and carcass characteristics were studied in sheep. Nine wether lambs at 10 wk of age were immunized with a conjugate of sulphated CCK octapeptide and human serum globulin or against human globulin alone. All CCK-immunized lambs produced antibodies, and the average titer 5 wk after the primary immunization was calculated to be sufficient to bind normal circulating levels of CCK. Mean daily feed intakes and BW were similar in the CCK-immunized and the control-immunized groups at the start of treatment, but after immunization, feed intake, appetite, and BW gain were decreased in the CCK-immunized animals. There was no effect on carcass composition or organ growth relative to body growth. It is concluded that the immunization procedure used in this study may have potentiated the actions of CCK rather than neutralizing its action as an appetite regulator.     

Differences in Reproductive Performance, Embryo Development, Interferon-tau Secretion by the Conceptus and Luteal Function in Ewe Lambs Synchronized in Oestrus before or after the Spontaneous Onset of Luteal Activity Preceding Puberty

In mid-September, 1 month before the insertion of intravaginal pessaries to induce sexual activity, blood samples were collected every 4 days from 16 ewe lambs aged 7 months, in order to determine the incidence of ovulations by measurement of plasma progesterone concentrations. It has been studied whether the response to a progestagen treatment of ewe lambs apparently close to puberty could be modified by the onset of the ovarian events preceding puberty. The effect of the presence or absence of ovulations prior to progestagen treatment on the potential reproductive performance (fertility, litter size and fecundity), embryo development [embryo quality and interferon-tau (IFNτ) secretion], luteal function (progesterone secretion in vitro ) and endometrial progesterone content was studied in seven ovulating (Ov+) and nine nonovulating ewe lambs (Ov−) on day 14 after mating. The best potential reproductive results were obtained with Ov+ animals, although these differences could not be initially attributed to either different progesterone secretion in vitro or concentration of endometrial progesterone. Irrespective of the experimental groups, secretion of progesterone by luteal tissue from ewe lambs with normal embryos was significantly greater (p<0.05) than that of animals with abnormal embryos or with no embryos. Normal embryos secreted a higher amount of IFN-τ than those embryos classified as abnormal (p<0.07). In conclusion, ewe lambs which exhibit luteal activity before puberty have the highest levels of reproductive performances after a progestagen treatment. Corpora lutea from ewe lambs with normal embryos had higher rates of progesterone secretion in vitro and their embryos had a higher IFN-τ production by the embryos, indicating greater capacity for subsequent development.     

Resistance to gentamicin and amikacin of gram-negative organisms isolated from horses

Resistance of gram-negative bacteria to gentamicin has become an increasingly common problem among clinical isolates from human beings. Susceptibility of isolates from horses to gentamicin and amikacin was evaluated for the period from July, 1983 to June, 1985. All isolates of Escherichia coli, and species of Enterobacter, Klebsiella, Proteus, and Pseudomonas examined were susceptible to amikacin, except 2 of the 46 Pseudomonas isolates. In contrast, 13 to 50% of isolates were resistant to gentamicin. Escherichia coli, and Klebsiella, Proteus, and Enterobacter species isolates were highly significantly more susceptible to amikacin (P less than 0.01) than to gentamicin. Pseudomonas spp (P = 0.13) were not significantly different in susceptibility to the 2 drugs. There was significant variation among genera in their susceptibility to gentamicin (P = 0.002), primarily because of the frequency of resistance in isolates of Klebsiella spp and Proteus spp, compared with the other 3 organisms (E coli, Enterobacter spp, and Pseudomonas spp). There was no significant difference of susceptibility to amikacin among the genera studied (P = 0.06).     

Caecal intussusceptions in horses: a New Zealand perspective

Objective To establish the prevalence of intussusceptions involving the caecum in a population of horses admitted to a university hospital for colic. Design Retrospective clinical study Methods Medical records of all horses admitted to the Massey University Veterinary Teaching Hospital between 1991 and 2004 were examined for information of those horses diagnosed with an intussusception involving the caecum. Results A total of 135 horses were admitted for colic surgery during the study period and 61 horses had a diagnosis of ileocaecal (37), caecocaecal (5) or caecocolic intussusception (19) made either at surgery or necropsy. Of the horses with ileocaecal intussusception, 32 had an incomplete hand-sewn ileocaecostomy without reduction and 29 survived to discharge. All the horses with caecocaecal intussusceptions were diagnosed preoperatively via rectal examination and/or transabdominal ultrasound: 2 were euthanased at surgery and 3 survived to discharge. In the 19 horses with caecocolic intussusceptions, manually reduction at surgery was performed in 6 and 5 of them survived to discharge. A typhlectomy was performed via a colotomy in 6 horses, 3 of which survived to discharge. Conclusions The high prevalence of intussusceptions involving the caecum seen at this referral centre may indicate a higher prevalence in New Zealand than is reported elsewhere in the world. Clinical relevance Intussusceptions involving the caecum should be considered as a differential diagnosis in horses presenting with chronic low-grade colic. Transabdominal ultrasound is useful for identifying caecocaecal and caecocolic intussusceptions. Hand-sewn side-to-side incomplete ileocaecostomy is a quick, effective and safe method of surgical treatment of ileocaecal intussusceptions.     

New techniques for the assessment and optimal management of growth and standing crop variation in the cultured freshwater prawn, Macrobrachium rosenbergii

The current ‘traditional’ prawn pond management system really does not ‘manage’, but rather accommodates prawn production characteristics and was instituted with a minimum knowledge of prawn biology and husbandry. As such, the traditional system is not optimal because it does not rely on a strong empirical knowledge base. Prawn culture has succeeded up until now because Macrobrachium rosenbergii is easily cultured and will give 500–1000 kg ha⁻¹ year⁻¹ without much effort. This is sufficient in many areas of the world but not in others where economic conditions have break-even production requirements of nearly 1 tonne greater than this. The traditional system relying on selective harvesting with large seine nets is seriously inefficient which not only leads to lost revenue but under-manages pond growth since unculled large animals suppress the growth of unculled smaller ones. The degree to which this occurs was not known to the designers of the traditional system who had no way of knowing (as we do now from our research results) the extremely large compensatory growth capability of small prawns in the absence of large ones. The traditional system also does not manage sexual dimorphic growth because no technology exists which can be used to create monosex broods or manipulate the sex ratio in ponds. Accurate production models are not available because traditional ponds are rarely sampled and/or rarely drained. This, along with inefficient harvests, results in a co-mingling of cohort stocking classes. It is impossible to get accurate survival and growth data because of this and because it is so time consuming to sample commercial ponds and process the data on a regular basis. This paper describes four new engineering and ‘bioengineering’ techniques which are under development and can overcome all the drawbacks of the traditional system: (1) surgical sex reversal to create monosex broods; (2) genetic tagging of stocking and resident cohorts to assess survival and growth; (3) size grading and 100% efficient harvesting using pond draining and a machine grader-harvester; and (4) a semi-automated computer assisted prawn sample data management system which uses sonic digitization of prawn sample data.