Preference for flavored wheat straw by lambs conditioned with intraruminal infusions of starch administered at different times after straw ingestion

We hypothesized that the development and extinction of preferences for flavored foods paired with infusions of starch depends on the delay between food ingestion and starch administration and on the frequency of starch administration. To test this hypothesis, we divided 24 lambs into three groups of 8 lambs/group. On even days, half of the lambs were offered chopped wheat straw flavored with a distinctive flavor, whereas the other half received straw with a different flavor. Starch (12% of the daily DE required by the lambs) was infused into the rumen immediately after lambs began to eat straw in Group 1 (150 g starch), immediately after lambs began to eat straw (75 g) and 30 min later (75 g) in Group 2, and when straw refusals were collected 1 h after lambs began to eat straw in Group 3 (150 g). On odd days, the flavors were switched and infusions of starch were replaced with water. After 8 d of conditioning, starch infusions were suspended, and lambs were offered a choice of wheat straw with the two distinctive flavors. All lambs acquired strong preferences for flavored straw paired with starch (P< .001), but the delay between straw ingestion and starch infusion affected preferences (P<.05). Lambs that received starch 1 h after beginning to eat straw (Group 3) had lower preferences than lambs that received starch immediately after beginning to eat straw (Groups 1 and 2). Lambs that received two starch infusions (Group 2) did not show higher preferences for flavored straw than lambs that received only one starch infusion immediately after beginning to eat (Group 1). Lambs in our study retained preferences for at least 17 d when eating straw was no longer reinforced with starch (P<.001). However, preferences were less persistent for lambs that received starch immediately after beginning to eat straw (Group 1) than for lambs that received starch in two pulses (Group 2) or lambs that received starch 1 h after beginning to eat straw (Group 3). Collectively, our results support the hypothesis that the delay between food ingestion and starch administration affects food preferences of lambs. These findings suggest that manipulating the chemical characteristics of foods, which affects the kinetics of forage degradation in the rumen, can increase food preferences in ruminants.     

Effects of acute asphyxia at birth on subsequent heat production capacity in newborn pigs

The effect of acute asphyxia at birth on subsequent ability to produce heat was investigated in 30 newborn pigs. A model of experimentally induced asphyxia consisting of the prevention of breathing within the first four minutes of life was used. Blood was sampled from an umbilical artery catheter within the first 75 minutes of life for blood gas, pH, glucose, lactate and catecholamine analysis. After the treatment and 24 hours later, heat production capacity, shivering intensity and rectal temperature were measured 10 degrees C below thermoneutrality. Effects on blood gas parameters were severe but transient whereas alterations in carbohydrate metabolism were maintained during the first 75 minutes (P < 0.05). Acute asphyxia at birth induced only minor alterations of thermoregulatory abilities during the first day of life: rectal temperature was lower one hour after birth (P < 0.05) and the postnatal increase in heat production capacity was less pronounced than in controls. It is suggested that the lower viability usually reported for piglets suffering from asphyxia during delivery is most likely to result from reduced vigour and colostrum intake, as well as altered carbohydrate metabolism early after birth.     

Pharmacokinetics of eprinomectin in plasma and milk following topical administration to lactating dairy cattle

The pharmacokinetics and mammary excretion of eprinomectin were determined in cattle following topical administration at a dose rate of 0.5 mg kg(-1). The kinetics of plasma and milk concentrations were analysed using a one-compartment model. The maximum plasma concentration of 43.76 ng ml(-1)occurred 2.02 days post administration, and the mean residence time was 4.16 days. Eprinomection was detected in the milk at the first sampling time and thereafter for at least 15 days. Comparison of the milk and plasma data demonstrated the parallel disposition of the drug in the milk and plasma with a milk / plasma concentration ratio of 0. 102+/-0.048. The amount of drug recovered in the milk during this period was 0.109% +/- 0.038 of the total administered dose. This very low extent of mammary excretion resulted in low concentrations of eprinomectin in milk. This supports the permitted use in lactating cattle, as the maximum level of residue in milk did not exceed the maximum acceptable limit of 30 ng ml(-1).     

Relationship of fatty acid composition to intramuscular fat content in beef from crossbred Wagyu cattle.

The deposition of i.m. fat, or marbling, in cattle is recognized as a desirable carcass trait in North American beef grading schemes. In order to investigate the relationship between degree of marbling and fatty acid composition of whole bovine muscle, we extracted the total lipid from pars costalis diaphragmatis (PCD) (n = 23) and longissimus (n = 36) muscles from Wagyu crossbred cattle that were assigned Canadian Grading Agency marbling scores ranging from 1 to 8 on an inverse 10-point scale (i.e., a score of 1 indicated "very abundant" marbling and a score of 10 would be assigned to a carcass "devoid" of marbling). Fatty acid methyl esters (FAME) of the total lipid and triacylglycerol fractions were resolved and quantified through GLC. Marbling scores were negatively associated with total lipid from both PCD (r = -.57, P < .01) and longissimus (r = -.80, P < .001). Differences between PCD and longissimus were found for almost all FAME studied from both lipid fractions, but no differences (P > .05) were seen when the monounsaturated:saturated fatty acid (MUFA/SFA) ratios were compared. Heifers had higher (P < .05) oleic acid content and lower (P < .05) palmitic acid content in lipid extracted from both muscles, resulting in higher (P < .05) MUFA/SFA ratios than those for steers. The relative amount of myristic acid increased as the lipid content (total lipid and triacylglycerol) increased in either longissimus (r values from .48 to .55; n = 36; P < .01) or PCD muscles (r from .67 to .76; n = 23; P < .001). The relative amount of linoleic acid (cis-9, cis-12 isomer) from total lipid was negatively associated with all chemical measurements of lipid from the longissimus (r from -.52 to -.64; n = 36; P < .001) and PCD muscles (r from -.75 to -.85; n = 23; P < .001). This association was not significant (P > .1) for either muscle when linoleic acid from the triacylglycerol fraction was examined, suggesting the negative association between this fatty acid and lipid content was due to a dilution of membrane phospholipids with increasing triacylglycerol. Indices of fatty acid elongase activity, calculated from FAME data, implicated the balance between this enzyme activity and fatty acid synthase as a source of variation between animals displaying various degrees of marbling and worthy of further investigation to better understand the process of marbling fat deposition in beef cattle.     

Attaching and effacing lesions in the large intestine of an eight-month-old heifer associated with Escherichia coli O26 infection in a group of animals with dysentery

Escherichia coli O26:K60, with genetic attributes consistent with a potentially human enterohaemorrhagic E. coli was isolated from the faeces of an eight-month-old heifer with dysentery. Attaching and effacing lesions were identified in the colon of a similarly affected heifer examined postmortem, and shown to be associated with E. coli O26 by specific immunolabelling.     

Antibody response to glycoprotein E after bovine herpesvirus type 1 infection in passively immunised, glycoprotein E-negative calves

This study was conducted to determine whether young calves with maternal antibodies against bovine herpesvirus type 1 (BHV-1) but without antibodies against glycoprotein E (gE) can produce an active antibody response to gE after a BHV-1 infection. Five calves received at birth colostrum from gE-seronegative cows which had been vaccinated two or three times with an inactivated BHV-1, gE-deleted marker vaccine. After inoculation with a wild-type virulent strain of BHV-1, all the passively immunised gE-negative calves shed virus in large amounts in their nasal secretions. All the calves seroconverted to gE within two to four weeks after inoculation and then had high levels of gE antibodies for at least four months. The development of an active cell-mediated immune response was also detected by in vitro BHV-1-specific interferon-gamma assays. All the calves were latently infected, because one of them re-excreted the virus spontaneously and the other four did so after being treated with dexamethasone. The results showed that under the conditions of this work the gE-negative marker could also distinguish between passively immunised and latently infected calves.     

Rhinopneumonia or mycotoxin intoxication? Neurologic phenomena in horses from a riding school

In the course of several days most of the 40 riding-school horses turned out in paddocks developed ataxia of variable severity. Five of these horses showed severe ataxia and tremors, became paralyzed and were euthanized. Eleven privately-owned horses which were stabled on the same premises showed no clinical signs. The most likely diagnosis seemed to be the 'neurological form of EHV1', although the signs were not entirely typical. A few weeks later a second outbreak occurred among the riding-school horses and one of the privately-owned horses also showed signs of ataxia. In the meantime it had been shown that EHV1 titers in paired serum samples had not increased and that the cerebrospinal fluid of one of the severely affected horses was normal. Toxicological examination of hay, delivered just before the first outbreak and stored for the winter, showed a significantly increased concentration of lolitrem B mycotoxin (5-6 mg/kg). The hay appeared to have been made of ryegrass used for lawns and playing fields. Retrospectively it became probable that this hay occasionally been fed to the horses just before the onset of clinical problems. It is concluded that the horses showed the 'ryegrass-stagger syndrome'.     

Anaesthesia of a Sumatran tiger on eight occasions with ketamine, medetomidine and isoflurane

CASE: An 18-month-old male Sumatran tiger was referred for endoscopy and dilatation of an oesophageal stricture. Anaesthesia and bouginage was undertaken on eight occasions 2-3 weeks apart to dilate the oesophageal stricture. CLINICAL FINDINGS: On the first occasion, sedation was induced with a combination of medetomidine (30 microg/kg) and ketamine (2.35 mg/kg) given intramuscularly. Cardiopulmonary depression (characterised by bradycardia, ventricular arrhythmias, hypoventilation and cyanosis) was severe and in subsequent anaesthesias the medetomidine dose was decreased to about 18 microg/kg and the ketamine dose increased to about 3 microg/kg given intramuscularly. Immobilisation was adequate and the severity of the cardiopulmonary depression was reduced at the revised drug dosages. Atipamezole was effective in reversing both the cardiopulmonary and central nervous system depression. CONCLUSION: The dosage of medetomidine and ketamine recommended in the literature for immobilising tigers produced severe cardiopulmonary depression in this animal. A reduced dosage of medetomidine and higher dosage of ketamine provided adequate restraint with decreased cardiopulmonary depression.     

Productive,Physiological and Biochemical Changes in Imported and Locally Born Friesian and Holstein Lactating Cows under Hot Summer Conditions of Egypt

Twenty each of healthy lactating Friesian and Holstein cows were studied. They were of similar age and body weight, nonpregnant in their third lactation and 80–100 days post partum. The investigation was carried out for 8 weeks on two farms at the same time during the hot summer season in Egypt. The first farm was in Demietta (North east of the Nile Delta, 31° 40 N) on 20 Friesian cows and the second was in Fakous (East of the Nile Delta, 30° 40 N) on 20 Holstein cows. On each of the two farms, 10 cows were newly imported and 10 were born in Egypt.The average daily milk yield and total milk production in the third lactation of the newly imported cows were significantly higher than those of the locally born cows for both Friesians and Holsteins. At the same time, the T₄, T₃, urea-N, haematological values and AST enzyme activity in the newly imported cows were significantly lower than those in the locally born ones in both breeds, while the locally born cows showed significantly lower values for rectal temperature and respiration rate, as well as for AST and Alk-P enzyme activities, than the newly imported cows of either breed.Holstein cows surpassed the Friesians in milk production, as well as thyroid hormone secretion and cholesterol, haemoglobin, packed cell volume and erythrocyte count values. The opposite was found for serum total protein, urea-N and creatinine concentrations, leukocyte count and AST, ALT and Alk-P enzyme activities.