Milk Yield of Holstein Cows Induced into Lactation Twice Consecutively and Lactation Curve Models Fitted to Artiifcial Lactations

Nineteen multiparous barren Holstein cows were subjected to an induction of lactation protocol for 21 d administering estradiol cypionate （2 mg kg-1 of body weight （BW） d-1, on day 1 to 14）, progesterone （0.10 mg kg-1 of BW, on day 1 to 7）, lfumethasone （0.03 mg kg-1 of BW, on day 18 to 20） and recombinant bovine somatotropin （rbST;500 mg per cow, on day 1, 6, 16 and 21）. At the end of lactation and with a minimum of a 2-mon dry period, the same cows were again hormonally induced into lactation. Cows in both lactations were not artiifcially inseminated, they were milked 3 times daily and received rbST throughout lactation. Mean accumulated milk yield at 305 d in milk （DIM） did not differ between the ifrst and second induced lactations （（9 710 ＆#177;1 728） vs. （9 309＆#177;2 150） kg;mean＆#177;SD）. Total milk yield （（12 707＆#177;3 406） vs. （12 306＆#177;4 218） kg;mean＆#177;SD） and lactation length （（405＆#177;100） vs. （410＆#177;91） d;mean＆#177;SD） were not different between the ifrst and second induced lactations. In a second study, 15 empirical models including exponential, power law, yield-density, sigmoidal and miscellaneous models were compared for their suitability by modeling 12-mon （n=334）, 18-mon （n=164） and 29-mon （n=22） lactation cycles of Holsteins cows induced into lactation and treated with rbST throughout the lactation. Hoerl （Y=ab1/xxc）, Wood （Y=axb exp（cx）） and Dhanoa （Y=ax（bc）exp（cx）） models were equally suitable to describe 12-mon lactations. An exponential model with ifve parameters （Y=exp（a＋bx＋cd2＋e/x）） showed the best ift for milk yield for 18-mon lactations. The rational model （Y=a＋bx/1＋cx＋dx2） was found to produce the closest ift for 29-mon lactations. It was concluded that, with the protocol used in the present study, multiparous cows respond favorably to a second cycle of induced lactation, with milk yield similar to that experienced during the ifrst cycle. Thus, dairy producers might be able to lengthen the productive life of infertile high producing cows with a renewal of artiifcial lactation, which would imply an overall reduction in voluntary culling of cows. Also, various equations used to describe the lactation curves demonstrated the potential for iftting monthly milk records of Holstein cows with prolonged lactations and induced hormonally into lactation.     

Treatment of rupture of suspensory ligament and superficial flexor tendon in a bull

Rupture of the suspensory ligament at the insertions on the proximal sesamoid bones, and of the superficial flexor tendon of the left fore limb, occurred in an adult Angus bull as a result of fighting. There was severe hyperextension of the metacarpophalangeal (MCP) joint with the dewclaws almost touching the ground. Radiographs revealed severe hyper-extension of the MCP joint with the sesamoid bones aligned directly distal to the metacarpus. Initially, a full length fiberglass cast was applied with the limb partially flexed within the cast and the heels elevated. The cast was replaced twice. The cast was removed after 136 days and the bull was bearing full weight on the limb. Prolonged immobilisation of the limb produced new bone in the area (a normal response in cattle) to cause ankylosis of the traumatized MCP joint and partial ankylosis of the carpus. The bull was being used for pasture breeding one year after the injury.     

Vascular Response of the Equine Radius to Cerclage Devices

The arterial blood supply to the diaphysis of the radius, and the vascular reaction when three cerclage devices (cerclage wire, Parham-Martin band, and a partially contacting band) were applied 2 cm apart, were studied in six adult ponies. The opposite radial diaphysis served as the control. Ponies were euthanatized at weeks 4 and 8. A centrifugal blood flow pattern was demonstrated by microangiography. Larger numbers of medullary arteries exist in equine than in canine and human long bones. Changes in centrifugal blood supply were not identified beneath any of the cerclage devices.     

Oral transmission of transmissible gastroenteritis virus by muscle and lymph node from slaughtered pigs

A study was conducted in the USA to determine whether transmissible gastroenteritis (TGE) virus could be transmitted from carcases of slaughtered pigs. Transmissible gastroenteritis virus was transmitted to 6-day-old piglets by dosing with homogenates of muscle and lymph node collected from 500 clinically normal pigs at the time of slaughter. All piglets in 2 separately housed litters showed clinical signs of TGE with 5 piglets dying within 10 d of oral dosing with homogenates. Transmissible gastroenteritis virus was isolated from 2 of these piglets and all piglets developed TGE antibody. Transmissible gastroenteritis virus was not isolated in tissue culture from muscle and lymph node homogenates, but was isolated from 4 (0.8%) of 500 tonsil samples collected from the same pigs. A survey of 250 serum samples provided an estimate of the prevalence of slaughtered pigs with TGE antibody of 34.8% in the sample population. The results indicate that carcases of some pigs from TGE endemic areas contain viable TGE virus, and that there would be a substantial risk of introducing TGE virus into Australia by the importation of uncooked pig meat from these areas.     

A longitudinal study of lymphocyte subsets in a cohort of cats naturally-infected with feline immunodeficiency virus

Despite the potential of feline immunodeficiency virus (FIV) as an animal model for human immunodeficiency virus (HIV) studies, the long term effects of naturally-occurring infection have not been determined. HIV infection causes an ongoing deterioration in immune function which directly correlates with disease, in particular acquired immunodefciency syndrome (AIDS). However, it is not known whether FIV-induced immunosuppression is progressive or related to the clinical condition. This study examined changes in lymphocyte subset numbers of serial samples, taken from cohorts of FIV-positive and FIV-negative cats over an 18-month period. FIV-positive cats were clinically staged as asymptomatic carriers (AC) or cats with AIDS-related complex (ARC), and FIV-negative cats matched and staged on the basis of similar diseases. During the course of the study, 4 FIV-positive cats developed AIDS, classed as the terminal stage of infection. There were no significant differences in the mean absolute numbers of any lymphocyte subset between the onset (to) and the completion (t18) of the study. Similarly there were no significant changes in subset numbers during the 18 months preceding the development of AIDS. While the study period was brief and the sample sizes small, it is postulated that FIV infection in Australia may not necessarily cause progressive immunodeficiency and that FIV-induced immunosuppression (as measured by subset analysis) may not be well correlated with the clinical status of the infected cat.     

Determination of Safe Depth of Pin Penetration for Repair of Distal Femoral Physeal Fractures in Immature Dogs: A Comparison of Normograde and Retrograde Pin Placement

Objective —The purpose of this study was to determine the depth that implants may be safely placed into the distal femoral epiphysis (DFE) for the repair of distal femoral physeal fractures.
Study Design —The depth of the DFE was related to the radiographic thickness of the patella in this experimental study.
Animals or Sample Population —Twenty immature canine cadavers.
Methods —Patella thicknesses were measured from lateral radiographs. Actual DFE depths were determined for pins driven in normograde fashion and for pins driven retrograde from the central depression between the metaphyseal pegs and from the cranial pegs. The association of DFE depth and patella thickness was evaluated using linear regression analysis. Using 95% confidence intervals, rules for estimating the safe depth of implant placement into the DFE were determined.
Results —DFE depth had significant correlation with patella thickness for pins placed in retrograde fashion from the central depression between the metaphyseal pegs (r²= .83) and from the cranial pegs (r²= .82) and for pins placed in normograde fashion (r²= .65).
Conclusions —Based on 95% confidence intervals, pins placed in retrograde fashion from the central depression between the metaphyseal pegs may be safely driven into the DFE a distance equal to 140% of patella thickness. Pins placed from the cranial metaphyseal pegs may be driven to a depth equal to 80% of patella thickness, and pins placed in normograde fashion may be driven to a depth equal to 30% of patella thickness.
Clinical Relevance —Measurement of patella thickness assists the surgeon in determining the approximate depth that pins may be driven into the DFE without penetrating the articular surface of the stifle joint.     

Conservative management of minimally displaced radial fractures in three horses

Minimally displaced, spiral, radial fractures were diagnosed in three adult horses. Two horses had open fractures and in one horse the fracture was closed. A diagnosis was made on radiographs taken 24 h, 5, and 9 days after the fracture. There was minimal displacement of the fracture fragments despite the considerable time which had elapsed between fracture and diagnosis and an unfavourable prognosis with internal fixation, so conservative therapy was the preferred method of treatment. One horse developed a sequestrum and draining sinus, which was treated surgically under general anaesthesia 3 months after diagnosis of the fracture. Other complications were minimal and transient. Two horses were being used for pleasure riding 12 months after fracture and one horse was pasture sound at 8 months.