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New Zealand Veterinary Journal Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tnzv20
Some aspects of lameness in dairy herds H.F. Dewes
a
a
150 Te Rapa Road, Hamilton Published online: 23 Feb 2011.
To cite this article: H.F. Dewes (1978) Some aspects of lameness in dairy herds, New Zealand Veterinary Journal, 26:6, 147-159, DOI: 10.1080/00480169.1978.34524 To link to this article: http://dx.doi.org/10.1080/00480169.1978.34524
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
1978
147
NEW ZEALAND VETERINARY JOURNAL
Some aspects of lameness in dairy herds H. F. Oewes lll N.Z vel. J. 26: 147-8 & 157-9
Downloaded by [UQ Library] at 15:29 03 November 2014
ABSTRACf
Excessive wear of the sole of the claws was a common cause of lameness in 2-year-old Friesian heifers. The lameness in older cattle frequently resulted from lesions sited in the interdigital space and in soft tissue structures elsewhere. Lameness was usually noted from 2-12 weeks after calving. Wear began soon after animals entered the herd and lameness resulted when animals walked long distances in wet conditions and after abrasive materials had accumulated on concrete holding yards. The time spent in yards, and the movement of animals on abrasive surfaces at each yarding, was influenced by the animal's ranking order of dominance and her sequence in the milking order. Lameness was often followed by delayed oestrus, poor breeding performance, shortened lactation, low yield of milk fat and a sudden drop in body weight. These animals were often CUlled. Preventative measures were extremely successful when directed at minimising wear, reducing the period heifers were confined in yards during milking sessions, and upgrading main raceways.
INTRODUCTION
The 50th Farm Production Report of the New Zealand Dairy Board contains a survey on lameness(9). The survey noted a prevalence of lameness among autumn-calving 2 to 3-year-old heifers and that serious economic losses result. It concluded that the cause of lameness in the Otaki-Levin area was an environmental one which could be overcome by upgrading races, especially where the terrain was difficult. An attempt was made during the 1975-76 dairy season in the Waikato area, adjacent to Hamilton, to isolate causes of lameness that could have their origins in the environment of the daily routine of dairying, or in some aspects of herd behaviour. In this area, foliage grazed by the animal commonly provides most of the metabolisable energy for maintenance, growth and milk production. If foliage is insufficient, supplements are supplied as hay, silage, fodder crops and meal. Cows in large dairy herds can be managed by a small labour force when they are milked in batches, conditioned to come and go their appointed ways at regular times, and find their own feed. Lame cows are always a nuisance. They move slowly and disrupt the smooth handling of the herd. They generally receive antibiotics but any additional treatment is rarely undertaken by the owner. MATERIAL AND METHODS
A study was made offour herds belonging to owners serviced by a mixed veterinary practice in the Waikato. These owners regularly sought treatment for cattle with lameness. The cattle were predominantly Friesian. Two herds produced milk for town-supply. Freshly-calved cows were introduced to the herd during the autumn and spring months. The other two herds were in production from July one year to May the next. Calving was • 150 Te Rapa Road, Hamilton.
concentrated within 6 weeks, from mid-July to the end of August. All owners agreed to supply a history together with information on breeding performance and production. They noted the type of lameness, the date lameness was first apparent, and if the lameness resolved rapidly after treatment initiated by them. The distance that animals walked each day on access races was measured on aerial maps and by a pedometer. Ages, dates of calving, weight of milk, estimated milk-fat and duration of lactations, were available for two of the herds from records supplied to owners by the Auckland Livestock Improvement Association, and some records of breeding performance were available for all four herds Culling records were complete for the 1974-75 season but, as the study was concluded in January 1976, owners had to be asked to nominate the animals likely to be culled during the remainder of the season. TABLE I: INCIDENCE AND ORIGIN OF LAME ANIMALS 4 HERDS 1975-76
Total animals in milk Older than 2 years 2 years old
Total Number
Number Lame
661 542 119
91 44 47
% 14 8
40
TABLE II: FREQUENCY OF LAMENESS IN FORE AND HIND FEET
Hind Foot Both Hind Feet Fore Feet
AGE 2 YEARS
OLDER THAN 2 YEARS
10
14
5
4
4
RESULTS
Incidence of Lameness (Table I) One sixth of the animals in lactation were 2-year-old firstcalving heifers, which replaced culls and deaths, thus representing the average rate of replacement in dairy herds in the district. The lame animals were apportioned evenly by age, w)l.en the age structure of the herds was taken into account. Time from Calving The earliest that 2-year-olds appeared lame after calving was 10 days and the latest was III days; the mean period was 63 days. Lameness was first noted in the remainder at 12 days, but individuals cropped up sporadically throughout the season. The mean period of 63 days reflected that trend. In both groups, however, slightly more than 85% were first noted lame between to and 90 days. Incidence in Fore and Hind Feet (Table II) Hind feet were more frequently involved, with lameness in both hind feet being quite common among the 2-year-olds but non-existent in the older group.
Classification of Lesions The routine adopted for examination was that each lame foot was lifted, restrained, scrubbed and the interdigital space searched. The superficial external horn was shaved off using a sharp hoof-knife and the sole was tested for pain and thickness by pressure. The site and cause of the lesion were noted. All cases seemed to fit into six clear categories (Table III):-
1. 2. 3. 4. 5. 6.
VOL 26
NEW ZEALAND VETERINARY JOURNAL
148
Stones embedded in the sole, heel or interdigital space. Tumours, or growths, of various kinds occupying part, or all, of the interdigital space. Footrot. Heat, pain and swelling in soft tissues, which responded rapidly to systemic antibiotics. Strains of tendons and joints (persistent pain, and swelling visible outside the hoof) unresponsive to antibiotics. Abscess formation beneath the horn of the sole. Solar laminae exposed on all four feet.
The Effect of Lameness on Production The performance of lame animals was compared with their normal counterparts which were selected from the common record of breeding performance and production, by the simple expedient of taking the data-entry closest in calving date. The measures developed were: (I) The average interval from calving to successful mating. (2) The weight of milkfat produced during the period the animal was in-milk. (3) The option exercised by the owner during, or at the end of, the period of production. The option being whether the farmer intended to retain, or cull, the animal at the end of the season.
Downloaded by [UQ Library] at 15:29 03 November 2014
TABLE III: CAUSES OF LAMENESS AGED 2 YEARS
2
6 3 11
25
4 7
Stones embedded in sole Interdigital tumours
Foot Rot
Strains of joints and tendons Abscess beneath hom of sole Exposed laminae all 4 feet
OLDER THAN 2 YEARS
I
Fig. 1. The foot ofa Freisian heifer showing signs ofwear. The solar surface is flat with the first point ofimpact being the axial wall and the periople of the heel. Note the dark cracks extending along the abaxial walls at the junction of the sole.
4
Abscess formation beneath the sole deserves special mention. Figures 1,2 and 3 illustrate the flat surface to the soles and the perioplic horn of the heels. The axial border has become the lowest margin of the bearing surface and, with the perioplic horn of the heel, the first to bear weight. Deep cracks have invaded the fusion between the sole and abaxial wall. The horn of the sole and heel was often ~tained red and straw-coloured (Fig. 4). The sole was easily depressed, usually thinnest above the abaxial border and most painful over the locus of pus. The animal was disinclined to· walk, spent long periods recumbent, seldom sought food and lost body weigh t very rapidly. A core of necrotic tissue occasionally developed adjacent to the abscess in elastic tissue. It was attended by even more severe pain. Sometimes two or more feet were tender. Rarely were these animals lame, but they did not feed or move about. Other abscesses in the same claw often developed with the appearance of lameness (Fig. 5). Length of Races and Distances Walked The lengths of the formed, main races for the four farms were 0.8, 1.6, 1.8, and 3.0 miles. One farmer, who milked 300 cows, estimated they walked 5.3 miles daily during the peak of lameness. In comparison, the average distance covered by the dairy cow when grazing is 2.5 miles and is, for the most part, covered in daylight(4). Proportion of 2-year-old Heifers Last in the Yards: The sequence in which animals pass through the milking shed is fixed soon after entry into the milking herd. The sequence is changed only rarely during the first 3 months in factory-supply herds, but is subject to greater change in herds supplying town-milk. In the first herd, 20 heifers and 9 cows remained last in the holding yards during milking; in the second herd, 10 heifers and 8 cows; in the third herd, 14 heifers and 7 cows and in the fourth herd, II heifers and 3 cows. Although heifers only made up one sixth of the herd, a much higher proportion were late in the sequence of milking.
Fig. 2. The same foot trimmed. Note the deep cracks at the junction ofthe sole and wall.
Fig. 3. A solar abscess. situated at the base ofa crack, opened and draining.
Fig. 4. Note the red and yellowdiscolouration of the solar horn, a result of trauma to laminae. Fibrin and erythrocytes have been incorporated into horn grooves.
(continued on page 157)
1978
157
NEW ZEALAND VETERINARY JOURNAL· (continued from page 148)
Effect on Milk Fat (Table V) Milkfat produced by individual animals was computed by the Livestock Improvement Association of Auckland and was reported regularly to two of the owners who used the service. Yields for the season were estimated on regularly collected samples taken throughout lactation. Other lame animals gave more fat and lactated longer then the lame 2-year-old heifers.
Fig. 5. A series ofabscesses have developed beneath the sole. The solar horn has offered minimal protection to the sensitive laminae.
Options Exercised by Owners (Table VI) When animals fail to mate successfully, to milk well enough, to keep up with the movements of the herd, or to maintain body weight, the option to cull is frequently exercised. Although 91 were recorded lame in Table I, accurate information could only be supplied for 73, owing to one herd being dispersed late in the season.
Downloaded by [UQ Library] at 15:29 03 November 2014
TABLE IV: INTERVAL FROM CALVING TO CONCEPTION (3 HERDS)
Fig. 6. A sample of sharp metal transported by the herd. This material accumulates in the yard during yarding for milking.
MEAN INTERVAL IN DAYS Normal Lame 2 yr Heifers Herd I 2 3
97 106 132
86 35
Herd I 2 3
92 102 99
72 42
*
Older than 2 yrs
•
* No others f(Jf'comparison (average calving intervalfor New Zealand dairy
Fig. 7. Abrasive material left 10 accumulate on the concrete link between the milking shed yards (foreground) and the main race (distant).
herds is 365 days and is optimum for seasonal dairying. Calving interval ideally consists of 283 days gestation plus 82 days from calving to conception).
TABLE V: COMPARISON OF PERFORMANCE OF TWO HERDS LAME Milkfat Days in (kg) Milk
2 yr Heifers Other than 2 yrs Fig. 8. A sharply angled entry frnm the main race to the concrete link leading to the yards.
NORMAL Milkfat Days in Milk (kg)
Herd I Herd 2
40 50
110 96
90 119
172 220
Herd 1 Herd.2
116 86
124 117
169 175
256 262
TABLE VI: CULLING OPTIONS EXERCISED BY OWNERS 2 year-old heifers (Nominated for culling or culled) Retained in herd Older than 2 years (Nominated for culling or culled) Fig. 9. The advance part of the herd moving warily on a race-surface ofwet chip-metal.
Retained in herd
LAME
NORMAL
17
Nil
16
33
8
2
32
40
DISCUSSION
The Average Interval from Calving to Conception (Table IV). The calving interval (one calving to the next) for the national herd. should be 365 days, and, in fact, is veryc\ose to it.(8). Ideally, gestation of283 days is followed by another 82 days later. A delay in conception shortens the length oflactation - a limit imposed by the management of dairy herds for seasonal pastoral farming. Animals which failed to conceive within 82 days of calving were culled without exception in the herds studied.
The diagnosis and treatment of lameness is burdensome at any time. Unless the means of restraint used is safe for both operator and animal, examination of the foot can sometimes be hazardous and a confident diagnosis is unlikely to be made. An animal that is tender and hot-footed from worn soles should be given time to grow and accumulate fresh horn. Animals in milk may re-enter the herd in about 10 days, provided walking on hard surfaces can be eliminated or kept to an absolute minimum.
Downloaded by [UQ Library] at 15:29 03 November 2014
158
NEW ZEALAND VETERINARY JOURNAL
They will have kept offtheir feet, fed less, lost some body weight and produced less milk than their contemporaries that are ambulatory normal. Should any develop an abscess beneath the sole in one or both hind feet, loss of body weight will be sudden. The yield of milk will also fall precipitously and, most often, the milk will not be suitable for collection. The likelihood of fresh lame individuals appearing, diminishes when they have been calved more than 80 days. The devastating effect lameness had on performance was not apparent until comparisons of breeding performance, milk yield and disposal of these animals was undertaken retrospectively. Lameness could then be linked directly with poor performance. The initial losses incurred during lameness appeared to be of minor importance. Losses for the full season were cumulative and substantial; the higher the incidence the greater the loss. Animals older than 2 years suffered less. Rarely were signs of wear prominent and only about one quarter were lame through abscesses developing beneath the soles. In general, lesions presented by the remainder responded readily to treatment. The high incidence among 2-year-old heifers, coupled with very similar changes in the feet, came as a surprise, The red and yellow discolouration of the horn ofthe sole suggested that blood and fibrin had recently been incorporated into growing horn exudates that could have arisen only through trauma to the laminae of the sole and the periople of the heel. The high border of the wall abaxially, and the concave contour between axial and abaxial sides of the claw, had disappeared completely. The toes of the claws no longer spread apart on impact. Protection to the sensitive structures within the hoof on impact and during limb-loading, could only be provided by the sole, a structure now radically modified. Besides being flat the sole had become thinnest at the abaxial border of the toe and wall. Here was the usual locus for abscess formation - right along the junction of the laminae of the sole and wall (Figs 1-4). These findings focussed attention on two questions. What was happening within these herds to produce such a high incidence among 2-year-old heifers? What combination of everyday happenings could greatly accelerate the process recognised as wear? The remainder of this discussion centres about consideration of behaviour distinctive to heifers and the surfaces encountered by their feet. Consideration of Behaviour and Environment Studies of the hierarchies in dairy herds, namely leadership/followship, dominance/subordinance, milking order and territory, have been reported(5). At this time (1958) herds were milked in 'walk -through' sheds - a row of bails, each with a door, roofed over. The holding yards were permanently subdivided. Average herd size then(lO) was 70 and many animals were the proud possessors of horns. By 1976 the average herd contained 127 animals in milk(l') and most were dehorned. The shed design had also changed. Remotely controlled, powered, back-gates were used to keep the cows up to the milk line. Those engaged in the milking procedure could now direct their full attention to what had become a sophisticated routine. The statemenrl) that "behavioural phenomena displayed by the animal in the advance movement of the herd are termed leadership", suggests an established leader, out in front, or near the front, of the herd. More recently
New Zealand Veterinary Journal Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tnzv20
Some aspects of lameness in dairy herds H.F. Dewes
a
a
150 Te Rapa Road, Hamilton Published online: 23 Feb 2011.
To cite this article: H.F. Dewes (1978) Some aspects of lameness in dairy herds, New Zealand Veterinary Journal, 26:6, 147-159, DOI: 10.1080/00480169.1978.34524 To link to this article: http://dx.doi.org/10.1080/00480169.1978.34524
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
1978
147
NEW ZEALAND VETERINARY JOURNAL
Some aspects of lameness in dairy herds H. F. Oewes lll N.Z vel. J. 26: 147-8 & 157-9
Downloaded by [UQ Library] at 15:29 03 November 2014
ABSTRACf
Excessive wear of the sole of the claws was a common cause of lameness in 2-year-old Friesian heifers. The lameness in older cattle frequently resulted from lesions sited in the interdigital space and in soft tissue structures elsewhere. Lameness was usually noted from 2-12 weeks after calving. Wear began soon after animals entered the herd and lameness resulted when animals walked long distances in wet conditions and after abrasive materials had accumulated on concrete holding yards. The time spent in yards, and the movement of animals on abrasive surfaces at each yarding, was influenced by the animal's ranking order of dominance and her sequence in the milking order. Lameness was often followed by delayed oestrus, poor breeding performance, shortened lactation, low yield of milk fat and a sudden drop in body weight. These animals were often CUlled. Preventative measures were extremely successful when directed at minimising wear, reducing the period heifers were confined in yards during milking sessions, and upgrading main raceways.
INTRODUCTION
The 50th Farm Production Report of the New Zealand Dairy Board contains a survey on lameness(9). The survey noted a prevalence of lameness among autumn-calving 2 to 3-year-old heifers and that serious economic losses result. It concluded that the cause of lameness in the Otaki-Levin area was an environmental one which could be overcome by upgrading races, especially where the terrain was difficult. An attempt was made during the 1975-76 dairy season in the Waikato area, adjacent to Hamilton, to isolate causes of lameness that could have their origins in the environment of the daily routine of dairying, or in some aspects of herd behaviour. In this area, foliage grazed by the animal commonly provides most of the metabolisable energy for maintenance, growth and milk production. If foliage is insufficient, supplements are supplied as hay, silage, fodder crops and meal. Cows in large dairy herds can be managed by a small labour force when they are milked in batches, conditioned to come and go their appointed ways at regular times, and find their own feed. Lame cows are always a nuisance. They move slowly and disrupt the smooth handling of the herd. They generally receive antibiotics but any additional treatment is rarely undertaken by the owner. MATERIAL AND METHODS
A study was made offour herds belonging to owners serviced by a mixed veterinary practice in the Waikato. These owners regularly sought treatment for cattle with lameness. The cattle were predominantly Friesian. Two herds produced milk for town-supply. Freshly-calved cows were introduced to the herd during the autumn and spring months. The other two herds were in production from July one year to May the next. Calving was • 150 Te Rapa Road, Hamilton.
concentrated within 6 weeks, from mid-July to the end of August. All owners agreed to supply a history together with information on breeding performance and production. They noted the type of lameness, the date lameness was first apparent, and if the lameness resolved rapidly after treatment initiated by them. The distance that animals walked each day on access races was measured on aerial maps and by a pedometer. Ages, dates of calving, weight of milk, estimated milk-fat and duration of lactations, were available for two of the herds from records supplied to owners by the Auckland Livestock Improvement Association, and some records of breeding performance were available for all four herds Culling records were complete for the 1974-75 season but, as the study was concluded in January 1976, owners had to be asked to nominate the animals likely to be culled during the remainder of the season. TABLE I: INCIDENCE AND ORIGIN OF LAME ANIMALS 4 HERDS 1975-76
Total animals in milk Older than 2 years 2 years old
Total Number
Number Lame
661 542 119
91 44 47
% 14 8
40
TABLE II: FREQUENCY OF LAMENESS IN FORE AND HIND FEET
Hind Foot Both Hind Feet Fore Feet
AGE 2 YEARS
OLDER THAN 2 YEARS
10
14
5
4
4
RESULTS
Incidence of Lameness (Table I) One sixth of the animals in lactation were 2-year-old firstcalving heifers, which replaced culls and deaths, thus representing the average rate of replacement in dairy herds in the district. The lame animals were apportioned evenly by age, w)l.en the age structure of the herds was taken into account. Time from Calving The earliest that 2-year-olds appeared lame after calving was 10 days and the latest was III days; the mean period was 63 days. Lameness was first noted in the remainder at 12 days, but individuals cropped up sporadically throughout the season. The mean period of 63 days reflected that trend. In both groups, however, slightly more than 85% were first noted lame between to and 90 days. Incidence in Fore and Hind Feet (Table II) Hind feet were more frequently involved, with lameness in both hind feet being quite common among the 2-year-olds but non-existent in the older group.
Classification of Lesions The routine adopted for examination was that each lame foot was lifted, restrained, scrubbed and the interdigital space searched. The superficial external horn was shaved off using a sharp hoof-knife and the sole was tested for pain and thickness by pressure. The site and cause of the lesion were noted. All cases seemed to fit into six clear categories (Table III):-
1. 2. 3. 4. 5. 6.
VOL 26
NEW ZEALAND VETERINARY JOURNAL
148
Stones embedded in the sole, heel or interdigital space. Tumours, or growths, of various kinds occupying part, or all, of the interdigital space. Footrot. Heat, pain and swelling in soft tissues, which responded rapidly to systemic antibiotics. Strains of tendons and joints (persistent pain, and swelling visible outside the hoof) unresponsive to antibiotics. Abscess formation beneath the horn of the sole. Solar laminae exposed on all four feet.
The Effect of Lameness on Production The performance of lame animals was compared with their normal counterparts which were selected from the common record of breeding performance and production, by the simple expedient of taking the data-entry closest in calving date. The measures developed were: (I) The average interval from calving to successful mating. (2) The weight of milkfat produced during the period the animal was in-milk. (3) The option exercised by the owner during, or at the end of, the period of production. The option being whether the farmer intended to retain, or cull, the animal at the end of the season.
Downloaded by [UQ Library] at 15:29 03 November 2014
TABLE III: CAUSES OF LAMENESS AGED 2 YEARS
2
6 3 11
25
4 7
Stones embedded in sole Interdigital tumours
Foot Rot
Strains of joints and tendons Abscess beneath hom of sole Exposed laminae all 4 feet
OLDER THAN 2 YEARS
I
Fig. 1. The foot ofa Freisian heifer showing signs ofwear. The solar surface is flat with the first point ofimpact being the axial wall and the periople of the heel. Note the dark cracks extending along the abaxial walls at the junction of the sole.
4
Abscess formation beneath the sole deserves special mention. Figures 1,2 and 3 illustrate the flat surface to the soles and the perioplic horn of the heels. The axial border has become the lowest margin of the bearing surface and, with the perioplic horn of the heel, the first to bear weight. Deep cracks have invaded the fusion between the sole and abaxial wall. The horn of the sole and heel was often ~tained red and straw-coloured (Fig. 4). The sole was easily depressed, usually thinnest above the abaxial border and most painful over the locus of pus. The animal was disinclined to· walk, spent long periods recumbent, seldom sought food and lost body weigh t very rapidly. A core of necrotic tissue occasionally developed adjacent to the abscess in elastic tissue. It was attended by even more severe pain. Sometimes two or more feet were tender. Rarely were these animals lame, but they did not feed or move about. Other abscesses in the same claw often developed with the appearance of lameness (Fig. 5). Length of Races and Distances Walked The lengths of the formed, main races for the four farms were 0.8, 1.6, 1.8, and 3.0 miles. One farmer, who milked 300 cows, estimated they walked 5.3 miles daily during the peak of lameness. In comparison, the average distance covered by the dairy cow when grazing is 2.5 miles and is, for the most part, covered in daylight(4). Proportion of 2-year-old Heifers Last in the Yards: The sequence in which animals pass through the milking shed is fixed soon after entry into the milking herd. The sequence is changed only rarely during the first 3 months in factory-supply herds, but is subject to greater change in herds supplying town-milk. In the first herd, 20 heifers and 9 cows remained last in the holding yards during milking; in the second herd, 10 heifers and 8 cows; in the third herd, 14 heifers and 7 cows and in the fourth herd, II heifers and 3 cows. Although heifers only made up one sixth of the herd, a much higher proportion were late in the sequence of milking.
Fig. 2. The same foot trimmed. Note the deep cracks at the junction ofthe sole and wall.
Fig. 3. A solar abscess. situated at the base ofa crack, opened and draining.
Fig. 4. Note the red and yellowdiscolouration of the solar horn, a result of trauma to laminae. Fibrin and erythrocytes have been incorporated into horn grooves.
(continued on page 157)
1978
157
NEW ZEALAND VETERINARY JOURNAL· (continued from page 148)
Effect on Milk Fat (Table V) Milkfat produced by individual animals was computed by the Livestock Improvement Association of Auckland and was reported regularly to two of the owners who used the service. Yields for the season were estimated on regularly collected samples taken throughout lactation. Other lame animals gave more fat and lactated longer then the lame 2-year-old heifers.
Fig. 5. A series ofabscesses have developed beneath the sole. The solar horn has offered minimal protection to the sensitive laminae.
Options Exercised by Owners (Table VI) When animals fail to mate successfully, to milk well enough, to keep up with the movements of the herd, or to maintain body weight, the option to cull is frequently exercised. Although 91 were recorded lame in Table I, accurate information could only be supplied for 73, owing to one herd being dispersed late in the season.
Downloaded by [UQ Library] at 15:29 03 November 2014
TABLE IV: INTERVAL FROM CALVING TO CONCEPTION (3 HERDS)
Fig. 6. A sample of sharp metal transported by the herd. This material accumulates in the yard during yarding for milking.
MEAN INTERVAL IN DAYS Normal Lame 2 yr Heifers Herd I 2 3
97 106 132
86 35
Herd I 2 3
92 102 99
72 42
*
Older than 2 yrs
•
* No others f(Jf'comparison (average calving intervalfor New Zealand dairy
Fig. 7. Abrasive material left 10 accumulate on the concrete link between the milking shed yards (foreground) and the main race (distant).
herds is 365 days and is optimum for seasonal dairying. Calving interval ideally consists of 283 days gestation plus 82 days from calving to conception).
TABLE V: COMPARISON OF PERFORMANCE OF TWO HERDS LAME Milkfat Days in (kg) Milk
2 yr Heifers Other than 2 yrs Fig. 8. A sharply angled entry frnm the main race to the concrete link leading to the yards.
NORMAL Milkfat Days in Milk (kg)
Herd I Herd 2
40 50
110 96
90 119
172 220
Herd 1 Herd.2
116 86
124 117
169 175
256 262
TABLE VI: CULLING OPTIONS EXERCISED BY OWNERS 2 year-old heifers (Nominated for culling or culled) Retained in herd Older than 2 years (Nominated for culling or culled) Fig. 9. The advance part of the herd moving warily on a race-surface ofwet chip-metal.
Retained in herd
LAME
NORMAL
17
Nil
16
33
8
2
32
40
DISCUSSION
The Average Interval from Calving to Conception (Table IV). The calving interval (one calving to the next) for the national herd. should be 365 days, and, in fact, is veryc\ose to it.(8). Ideally, gestation of283 days is followed by another 82 days later. A delay in conception shortens the length oflactation - a limit imposed by the management of dairy herds for seasonal pastoral farming. Animals which failed to conceive within 82 days of calving were culled without exception in the herds studied.
The diagnosis and treatment of lameness is burdensome at any time. Unless the means of restraint used is safe for both operator and animal, examination of the foot can sometimes be hazardous and a confident diagnosis is unlikely to be made. An animal that is tender and hot-footed from worn soles should be given time to grow and accumulate fresh horn. Animals in milk may re-enter the herd in about 10 days, provided walking on hard surfaces can be eliminated or kept to an absolute minimum.
Downloaded by [UQ Library] at 15:29 03 November 2014
158
NEW ZEALAND VETERINARY JOURNAL
They will have kept offtheir feet, fed less, lost some body weight and produced less milk than their contemporaries that are ambulatory normal. Should any develop an abscess beneath the sole in one or both hind feet, loss of body weight will be sudden. The yield of milk will also fall precipitously and, most often, the milk will not be suitable for collection. The likelihood of fresh lame individuals appearing, diminishes when they have been calved more than 80 days. The devastating effect lameness had on performance was not apparent until comparisons of breeding performance, milk yield and disposal of these animals was undertaken retrospectively. Lameness could then be linked directly with poor performance. The initial losses incurred during lameness appeared to be of minor importance. Losses for the full season were cumulative and substantial; the higher the incidence the greater the loss. Animals older than 2 years suffered less. Rarely were signs of wear prominent and only about one quarter were lame through abscesses developing beneath the soles. In general, lesions presented by the remainder responded readily to treatment. The high incidence among 2-year-old heifers, coupled with very similar changes in the feet, came as a surprise, The red and yellow discolouration of the horn ofthe sole suggested that blood and fibrin had recently been incorporated into growing horn exudates that could have arisen only through trauma to the laminae of the sole and the periople of the heel. The high border of the wall abaxially, and the concave contour between axial and abaxial sides of the claw, had disappeared completely. The toes of the claws no longer spread apart on impact. Protection to the sensitive structures within the hoof on impact and during limb-loading, could only be provided by the sole, a structure now radically modified. Besides being flat the sole had become thinnest at the abaxial border of the toe and wall. Here was the usual locus for abscess formation - right along the junction of the laminae of the sole and wall (Figs 1-4). These findings focussed attention on two questions. What was happening within these herds to produce such a high incidence among 2-year-old heifers? What combination of everyday happenings could greatly accelerate the process recognised as wear? The remainder of this discussion centres about consideration of behaviour distinctive to heifers and the surfaces encountered by their feet. Consideration of Behaviour and Environment Studies of the hierarchies in dairy herds, namely leadership/followship, dominance/subordinance, milking order and territory, have been reported(5). At this time (1958) herds were milked in 'walk -through' sheds - a row of bails, each with a door, roofed over. The holding yards were permanently subdivided. Average herd size then(lO) was 70 and many animals were the proud possessors of horns. By 1976 the average herd contained 127 animals in milk(l') and most were dehorned. The shed design had also changed. Remotely controlled, powered, back-gates were used to keep the cows up to the milk line. Those engaged in the milking procedure could now direct their full attention to what had become a sophisticated routine. The statemenrl) that "behavioural phenomena displayed by the animal in the advance movement of the herd are termed leadership", suggests an established leader, out in front, or near the front, of the herd. More recently
