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Biomedical subjects

P R Greenough

Publications and source records attributed to P R Greenough.

15 recordsLinked to original sources
PubMed2003

Effects of biotin supplementation on performance and claw lesions on a commercial dairy farm.

A controlled 14-mo field trial was conducted to evaluate the effect of biotin supplementation on hoof lesions, milk production, and reproductive performance in a commercial dairy herd. One hundred seventy cows were studied and supplemented with either 0 or 20 mg/d of biotin by computer feeder. All were housed in the same free-stall facility with the same environment, base diet, and management. The feet of 99 cows were trimmed three times at 6-mo intervals, and hoof health was evaluated. Milk production and fertility data were captured monthly by the Dairy Herd Improvement Association. At the final hoof trimming, sole hemorrhages were significantly higher in control (50%) vs. biotin-supplemented animals (24%). The incidents of cows affected with double soles, hoof wall grooves, and heel horn erosion did not differ between control and biotin-supplemented animals. Biotin supplementation of trimmed cows resulted in 878 kg more milk than control cows when compared with previous lactation yield (n = 46 biotin supplemented, n = 48 control cows). At the end of the study, for both trimmed and untrimmed animals, biotin supplemented cows (n = 81) produced 481 kg more milk and 25 kg more fat than the controls (n = 81). There was no interaction between biotin supplementation and hoof trimming on milk production. There were variations in the response of fertility to biotin between age groups. First lactation heifers fed supplemental biotin had significantly fewer days from calving to conception and required fewer inseminations per pregnancy than controls of the same parity.

Animal Nutritional Physiological Phenomena↗
PubMed2001

Sand cracks, horizontal fissures, and other conditions affecting the wall of the bovine claw.

The wall of the bovine claw is created only by the dermis beneath the coronary band. Keratogenic tissues in this region are susceptible to nutritional changes or stress, which changes the characteristics of the horn produced. Horizontal grooves or fissures result that weaken the claw wall and are instrumental in generating many vertical fissures. The rate at which the claw grows can be used to calculate the date of a nutritional insult.

Animal Nutritional Physiological Phenomena↗
PubMed2000

The effects of dietary biotin supplementation on vertical fissures of the claw wall in beef cattle.

A clinical field trial was performed on a herd of Hereford beef cows in central Saskatchewan. The herd had a history of being severely affected with vertical fissures. The objective of the study was to determine the effects of supplemental dietary biotin on the prevalence of vertical fissures in beef cows. In June 1994 and June 1995, 1- and 2-year-old heifers were randomly allocated into 2 treatment groups, each composed of 79 animals. One group received a 10 mg/head/day biotin-supplemented free-choice mineral supplement, while the other groups received an identical free-choice mineral without the biotin supplementation. The claws from these animals were evaluated in June 1994, October 1994, June 1995, October 1995, and June 1996 for the presence of vertical fissures. Supplemental dietary biotin significantly increased serum levels of biotin and significantly increased claw hardness in supplemented cows. Both groups of heifers started the trial without vertical fissures. After 18 months, 15% of the cows fed supplemental dietary biotin had vertical fissures compared with 33% in the nonsupplemented group. The difference was statistically significant (P = 0.01).

Animals↗
PubMed1999

A simple formula for predicting claw volume of cattle.

The object of this study was to develop a simple method for accurately calculating the volume of bovine claws under field conditions. The digits of 30 slaughterhouse beef cattle were examined and the following four linear measurements taken from each pair of claws: (1) the length of the dorsal surface of the claw (Toe); (2) the length of the coronary band (CorBand); (3) the length of the bearing surface (Base); and (4) the height of the claw at the abaxial groove (AbaxGr). Measurements of claw volume using a simple hydrometer were highly repeatable (r(2)= 0.999) and could be calculated from linear measurements using the formula:Claw Volume (cm(3)) = (17.192 x Base) + (7.467 x AbaxGr) + 45.270 x (CorBand) - 798.5This formula was found to be accurate (r(2)= 0.88) when compared to volume data derived from a hydrometer displacement procedure. The front claws occupied 54% of the total volume compared to 46% for the hind claws.

Animals↗
PubMed1996

Hock angles of dairy heifers in two management systems.

Hock angles were measured in 30 Holstein heifers in one herd housed either indoors on concrete slats or out of doors on dirt. Two examinations were made, i.e. at 12-13 and 24-26 months of age. Overall, the heifers had straight limbs; the mean value of the hock angle was 167.3 degrees +/- 0.7 (SEM) (range 154.3-177.4 degrees). Hock angles decreased with age in each group, but the difference between the first and second examinations was significant only for outdoor-housed heifers (P < 0.05). At the first examination, mean hock angles were not significantly different between the two groups (169.5 degrees +/- 1.6 vs 168.1 degrees +/- 1.6), but at the second examination indoor-housed heifers had significantly greater mean hock angles than heifers housed out of doors (167.4 degrees +/- 1.0 vs 164.2 degrees 1.3) (P < 0.05). Heifers housed indoors on concrete slats appeared to retain their straight-angled hocks.

Age Factors↗
PubMed1996

Sole haemorrhages in dairy heifers managed under different underfoot and environmental conditions.

Sole haemorrhages associated with laminitis were studied in 30 Holstein heifers in one herd housed either indoors on concrete or out of doors on a dry lot. Examinations were at 4-week intervals during a 15-month period from approximately 13 months of age to 2 months after calving. At 13 months of age, sole haemorrhages were present in 77% of the heifers. Five heifers, affected by clinical laminitis shortly after calving, developed early sole ulcers. Indoor-housed heifers had a greater number of and more severe haemorrhages than heifers managed in dry lots (P < 0.001). In both groups, hind claws were more affected than front claws (P < 0.001). Lateral claws were more affected in hind limbs (P < 0.001),whereas medial claws had more sole haemorrhages in front limbs (P < 0.01). Heifers managed in dry lots had more sole haemorrhages in right claws than in left claws (P < 0.01). The number and severity of haemorrhages differed among the six zones of the sole (P < 0.001). Overall, the abaxial white zone (zone 2) had the greatest number of haemorrhages, followed by the white zone at the toe (zone 0), the bulb (zone 5) and the sole-bulb junction (zone 4), respectively. Few haemorrhages occurred in the apex of the sole (zone 1) and the axial groove (zone 3). Zone 0 was more severely affected in heifers managed in dry lots (P < 0.001), whereas zones 2, 4 and 5 had greater numbers of haemorrhages in heifers housed indoors (P < 0.01). Time had no effect on total haemorrhages scores, but the effect of management was significant for zones 0 and 5. Total haemorrhage scores for zone 0 were greater in heifers managed in dry lots (P < 0.05), whereas zone 5 was more affected in indoor-housed heifers (P < 0.01). This study shows that sole haemorrhages do occur in the claws of dairy heifers managed either indoors or in dry lots, and permanent damage to the claws of these young cattle may already have occurred before they reach maturity.

Analysis of Variance↗
PubMed1996

Claw conformation of dairy heifers in two management systems.

A computerized conformation determination system was used to evaluate objectively claw conformation of dairy heifers in two management systems, i.e., housed indoors on concrete slats or out of doors in a dry lot. Examinations were made at 4-week intervals from 12-13 months of age until calving at 24-26 months. Overall, the angle of the dorsal border did not differ between front and hind claws. Length of the dorsal border, heel height, and toe:heel ratio were greater for front claws (P < 0.001). Hind claws were longer than front claws (P < 0.001), but front claws were wider (P < 0.001). On both front and hind limbs, lateral claws were wider than medial claws (P < 0.001). Angles of the dorsal border decreased, but lengths of the dorsal border and heel heights increased over time (P < 0.05). Significant differences in claw conformation were found between the two management groups. Heifers maintained out of doors had longer toes and wider lateral claws than heifers housed indoors (P < 0.05). At time of entry into the respective management group, no significant differences in claw traits were found between the two groups. At calving, however, out-door-housed heifers had hind claws with smaller dorsal angles and longer dorsal borders (P < 0.05).

Animals↗
PubMed1991

Evaluation of subclinical laminitis in a dairy herd and observations on associated nutritional and management factors.

The hind claws of 10 heifers, 10 second-calf cows, and 10 mature cows in the University of Saskatchewan's dairy herd were examined on four consecutive occasions, four and two months before calving, at calving, and two months after calving. A high prevalence of haemorrhages was observed in the sole of the claws, and these lesions were most prevalent near calving; the haemorrhages were detected in the heifers up to four months before calving. After calving, the haemorrhages tended to disappear rapidly from the claws of the heifers, but no such recovery was evident in the second calvers and mature cows. A scoring system for sole haemorrhages was developed, and the different scores were linked with sole ulcer (pododermatitis circumscripta), toe ulcer, white zone lesions, and heel erosion. Factors associated with nutrition and management, such as rapid rearing (average daily weight gain from birth to breeding greater than 800 g), the sudden introduction into the dry group after they had been confirmed pregnant, confrontation by dominant cows, and housing on concrete in a cubicle system appeared to play a role in the occurrence of haemorrhages in the claws of heifers well before calving.

Age Factors↗
PubMed1985

Development of an approach to lameness examination in cattle.

In the preceding pages, the various components of an examination have been described. Each clinician will formulate his own method of utilizing these components. The following are suggested steps in a practical approach to the diagnosis of lameness. Evaluate the conditions under which restraint of the animal is possible (corral, free stall, stanchion barn). Assess the temperament, physical strength, and general amenability of the animal to be examined. If the animal is at liberty, its movements can be studied. If it is standing quietly observe it. If the animal is tied up and it seems feasible to examine the animal while it is walking, observe the animal and take its history while it is still tied up. Aggressive and wild animals should be observed, but little beneficial information will be gained from a regional approach to evaluating movement at this stage. Even if the seat of lameness seems to be in the proximal limb, it is mandatory in every case to examine the hooves and interdigital space at some stage during the evaluation. However, if the probability of proximal lameness is high, the clinician may proceed to make a complete evaluation, which would include studying the quality of movement before checking that the distal extremity is normal in every way. If the clinician decides to proceed with an examination of the digital region and is unable to locate a causative lesion in the extremity, he would then evaluate movement and manipulate and palpate the proximal limb. If no cause of the lameness becomes apparent, the nerve supply to the extremity would then be blocked.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Alternatives to amputation.

Amputation of the digit of valuable animals is an inappropriate technique for resolving the serious infective processes that involve the important structures of the distal interphalangeal region. Surgeons should be able to recognize the early clinical signs and radiographic indications of three distinct, but interrelated, phenomena--the septic joint, the retroarticular abscess, and the complication of tenovaginitis. Tenovaginitis depends on either the septic joint or retroarticular abscess for its etiology. In any of these complications, the effective treatment will be based on the removal of diseased tissue and on irrigation with drainage of the area, followed by the elimination of mechanical forces or movement in the affected region.

Abscess↗
PubMedDate not supplied

Predisposing factors of laminitis in cattle.

Laminitis is regarded as a major predisposing factor in lameness caused by claw disorders. Despite intensive study, both by experiment and by clinical observation, knowledge of the precise aetiology and pathogenesis of bovine laminitis is still incomplete. It is often hypothesized that changes in the micro-circulation of the corum (dermis) of the bovine claw contribute significantly to the development of laminitis; arteriovenous anastomoses (AVAs) playing a crucial role. Many factors have been implicated as contributing causes of laminitis in cattle; the disease has a multifactorial aetiology. The cause of laminitis should be considered as a combination of predisposing factors leading to vascular (AVAs in particular) reactivity and inhibition of normal horn synthesis. Nutrition, disease, management and behaviour appear to be closely involved in the pathogenesis of bovine laminitis. The major factors predisposing to laminitis in cattle, as reported or suggested in the literature, are reviewed, including systemic disease, nutrition (barley grain, protein, carbohydrate and fibre), management (housing, bedding and exercise), calving, season, age, growth, genetics, conformation and behaviour.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

Structural characteristics of the bovine claw: horn growth and wear, horn hardness and claw conformation.

Claw quality is the product of horn characteristics, claw shape and anatomy and physiology of the inner structure. This paper aims to review some of the different approaches that have been employed to evaluate claw quality. The various factors that may influence horn growth and wear are reviewed, including physiological, seasonal, nutritional, environmental, management and anatomical aspects. Horn hardness is similarly described. Claw conformation is discussed, commencing with a brief outline of the various methods used to determine claw shape and size, followed by an account of some of the factors that influence claw conformation. The clinical importance of claw conformation in cattle is considered with particular reference to lameness, longevity and production traits. Finally, the prospect of improving claw quality by selection of bulls based on claw measurements is reviewed.

Animals↗
PubMedDate not supplied

Lesions associated with subclinical laminitis of the claws of dairy calves in two management systems.

Claws of ten 6 to 7-month-old dairy calves in two management systems were examined for lesions associated with subclinical laminitis. Sole haemorrhages were found only in claws of calves maintained out of doors. No significant differences in number and severity of haemorrhages were found between left and right or lateral and medial claws, but haemorrhages were more frequent and more severe in hind claws than in front claws (P < 0.05). More haemorrhages of greater severity were present in the white zone at the toe than in all other areas of the weight-bearing surface combined (P < 0.05). No lesions of interdigital dermatitis and heel horn erosion were found in either indoor-housed or outdoor-housed calves. All calves kept indoors on deep bedding developed overgrown claws.

Animal Husbandry↗