Evaluation of the digital cushion and weight-bearing surfac - PowerPoint Presentation

Slide1

Evaluation of the digital cushion and weight-bearing surface of the bovine foot in response to modifications in housing and rearing practices of calves

Mentor:

Julie Gard BS, DVM, PhD,

DACT

and Dr. Ray

Wilhite

Merial

Summer Scholar: Amy SandersSlide2

Lameness

One of the two most costly

diseases of the dairy industry (

1).

Prevalence in dairy herds is 20-50% of animals depending on age.

Establishment of husbandry systems to rear replacement heifers that are adept to withstand the rigors of the industry are badly needed.

What kind of changes can be made that can be utilized by today’s dairy farmers that will reduce the prevalence of lameness ?Slide3

Focus

Investigate a simple modification to the “industry standard” for replacement heifer husbandry that may help:

Decrease cull rates of dairy cows

Increase the size of the digital

c

ushion

Prevent lameness

Increase reproduction and milk productionSlide4

Hypothesis

Heifer claws will remodel in response to environmental conditions/stressors

Specifically, the digital cushions will become larger in response to the stimulation of increased exercise and housing on variable terrain

Life-long impact on animal health, welfare & productivity by decreasing the likelihood of lameness that is frequently seen during adulthood. Slide5

Preliminary Data – Study I

Performed with eight bull calves

Control group reared in accordance with industry standard practices

Treated group were allowed free access to a half mile long lane where they walked for a total of at least two miles a day on rocky terrain for 4 months time.

CT with 3-D analysis of P2 and P3 of the right rear foot from each calve was performed with

Mimics® medical image processing software.

Statistical

analysis by ANOVA showed that the surface areas of the bones of the digit were significantly (

P



0.05) larger in the treated calves vs. the control calves.

This data indicates

that bovine feet undergo structural adaptation in response to mechanical usage.Slide6

Preliminary Data – Study II

Performed with 20 bull calves

Control group (n=10) reared in accordance with industry standard practices

Treated group (n=10) were allowed free access to a half mile long lane where they walked for a total of at least two miles a day on variable terrain (grass, rocks, & dirt) for 4 months time.

MRI & 3-D analysis of the digital cushion of the right front and rear feet from each calve was performed with

Mimics® medical image processing software.

It was

found

that the treated group had a positive percent difference

in the volume and the surface area of the digital cushion,

37.10% and 18.25

%, respectively,

in comparison to the control

group, when corrected for weight.

This data also indicates

that bovine feet undergo structural adaptation in response to mechanical usage.Slide7

Significance/Literature Support

L

ameness has been described

as one of the two most costly diseases in the dairy industry due to the significant negative effects on the well-being and economic productivity of beef and dairy

cattle [1]

“...lameness is the most significant challenge for the dairy industry to overcome given obvious disruption of animal welfare and severe economic losses” [2,3,4]

Problems with lameness have the potential to lead to other production problems such as decreased milk production, reproduction, & mastitis

Cows detected with clinical lameness in the first 70 days in milk were 25% less likely to become pregnant compared to non-lame cows [3]. Slide8

Significance

Lameness can result

in earlier culling (removal from the herd by selling) of animals as well as lower carcass weight, conformation class, and fat cover class and hence a lower carcass economic value

.

Each episode of lameness is reported to cost between $302 and $446 with cost increasing with the severity of the lameness

[5,6]Slide9

Protection from the Digital Cushion

H

ousing has been shown to make

a significant impact on the strength/laxity, laminar morphology, connective tissue, and biochemistry of the sole

[9].

The digital cushion functions as a shock absorber and is protective to the structures underneath [2, 7

].

D

ecreases

in the thickness of the digital cushion in cattle are related to contusions with the claw horn capsule and such contusions are a consequence of the lesser capacity of the digital cushion to dampen the pressure exerted by the third phalanx on the soft tissue beneath [2,

8]. Slide10

Importance of the Digital Cushion

In a study by

Bicalho

, the prevalence of sole ulcers and white line disease was significantly associated with the thickness of the digital cushion; with cows in the upper quartile of digital cushion thickness had an adjusted prevalence  of lameness 15 percentage points lower than the lower quartile [2].

Digital Cushion: - 3 parts – middle,

abaxial

& axial

Raber

et al., 2004

http://www.sciencedirect.com/science/article/pii/S1090023303000534Slide11

Measurement of the Digital Cushion

The use of ultrasonography to measure the digital cushion was based off of

Bicalho’s

study in which the

thickness of the digital cushion was measured

ultrasonographically

from the junction of the heel and sole where a typical sole ulcer is located. [2]

Also

in previous studies, the measurement of the digital cushion was based upon age and lactation status while finding a correlation with the fatty acid content.

[10].

Our

proposal is basing the measurements of the deep digital flexor compared to the digital cushion off of the environment that the heifer is raised in after weaning. Slide12

Method

Control Group

6 months: 299

lbs

6 months: 339

lbs

5 months: 374

lbs

8 months: 452

lbs

8 months: 558

lbs

9 months: 604

lbs

8 months: 608

lbs

Treated Group

7 months: 344

lbs

6 months: 348

lbs

6 months: 354

lbs

8 months: 421

lbs

8 months: 458

lbs

9 months: 458

lbs

9 months: 518 lbs

14 Holstein heifers with random assignment of seven in each groupSlide13

Experimental Design

All calves were reared in accordance with the current accepted practices of the dairy industry.

At the randomized ages from 6-9 months

Control group was raised according to industry standards of the dairy husbandry at E.V. Smith Extension Unit

Treated group was maintained on a half mile long lane containing variable terrain at the North Auburn Beef Experiment Station.

Pedometers were placed on each group for the length of one week to determine steps/miles walked. Slide14

Treated Group

Encouraged to walk at least two miles per day by placement of food and water on opposite ends of the lane.

Goal study period is 13-18 months depending on the age of the heifers on day zero of study.

Slide15

Variable TerrainSlide16

Method

Calipers were used to measure the width and length of the medial and lateral claws of the left fore, & left rear legs of both groups

The digital cushions and deep digital flexor tendons of both groups were measured by ultrasound examination using a 6 MHz transducer at monthly intervals.

The Calf Number, Age, Body Condition Score, and Weight were all recorded as well along with the data. Slide17

Placement of ultrasound probe was the heal bulb at the level of the coronary band.

The heel bulb was cleaned with alcohol prior to ultrasound examinationSlide18

Ultrasound Utilization

The 6 MHz transducer

probe

was placed

on the bulb of the heel of each

claw

at the level of the coronary band (Figure 1)

Measurements were recorded of the deep digital flexor and the digital cushion. (Figure 2)

All calves were examined by ultrasound at day 0 & at monthly intervals. Slide19

DAY ZERO:Control GroupSlide20

Day Zero: Treatment GroupSlide21

DAY 30:Control GroupSlide22

DAY 30:Treatment GroupSlide23

Results

Control

TreatmentSlide24

Results

Currently, there is only a small difference between control and treated groups which may be attributed to normal variation among animals and from growth

Additional time is necessary to allow enough time for remodeling of tissues so recheck at monthly intervals.

The ultrasound method employed seems to be a viable tool for monitoring of the digital cushion of cattle

There was difference, however, in the health of the feet of the calves.

The control group had cases of

epiphysitis

, and dermatitis due to wet pasture

We believe the rocky terrain pasture didn’t have problems because it was drier and the movement of the calves helped keep them from standing in wet areas. Slide25

Results of Pedometers

Pedometers clipped onto cow leg straps were placed on four heifers from each group over a period of one week.

Only one pedometer from each group had results.

Control group= 5.1 miles total= 0.73 miles a day

Treatment group= 13.1 miles total = 1.9 miles per daySlide26

References

[1]

Kossaibati

MA, and

Esslemnont

RJ. The cost of production diseases in dairy herds

in

England. Vet J 1997;154:41-51

.

[2]

Bicalho

, RC, Machado VS,

Caixeta LS. Lameness in Dairy cattle: A debilitating disease

or a disease of debilitated cattle? A cross-sectional study of lameness

prevalence

and thickness of the digital cushion. J of Dairy Sci. 2009; 92:3175-3184

.

[3]

Bicalho

RC,

Vokey

CF,

Erb HN, Guard CL. Visual locomotion scoring in the first seventy days in milk: Impact on pregnancy and survival. J Dairy Sci. 2007b; 90:4586-4591.[4]Bicalho

RC,

Warnick

LD, Guard CL.

Stragtegies

to analyze milk losses caused by diseases with potential incidence throughout lactation: A lameness example. J of Dairy Sci. 2008; 91:2653-2661[5]Booth CJ, Warnick LD, Grohn YT, Maizon DO, Guard CL. Effects of lameness on culling on dairy cows. J Dairy Sci. 2004; 87:4115-4122[6]Guard C. The cost of lameness and the value of hoof care. Proc Hoof Care Conf. 1997; 4(abstract).

 [7]Cha E, Hertl JA

,

Bar D

,

Gröhn

YT

. The cost of different types of lameness in

dairy

cows calculated by dynamic programming.

Prev

Vet Med. 2010; 97(1):

1-8

[8]Knott

L

,

Tarlton

JF

,

Craft H

,

Webster AJ

. Effects of housing, parturition and diet

change

on the biochemistry and biomechanics of the support structures of the

hoof

of diary heifers. Vet J. 2007;174 (2):277-87.

[9]

Räber

M,

Lischer

Ch

J, Geyer H,

Ossent

P. The bovine digital cushion – a

descriptive

anatomical study. The Vet J. 2004;167:258-264

.

[10]

Izci

,

Celal

;

Erol

,

Muharrem

;

Goksahin

,

Ebru

. A Study

AboutDetermining

the Changes in the Structural Characteristics of the Digital Cushion in Heifer and

Multipar

Dairy Cows: A Preliminary Report. March 2011;

Kafkas

Universitesi

Veteriner

FakultesiDergisi;2011, Vol. 17 Issue 1,

p159Slide27

Special Thanks

Dr. Julie

Gard

Dr. Debra Taylor

Dr. Merilee Holland

Leah Guidry

Megan

Schnuelle

Will Justus

4

th

Year Ambulatory and

Therio

Students