Br. vet.]. (1975), 131, 70
THE FEEDING OF COPPER SULPHATE TO GROWING RABBITS By]. O. L. KING Veterinary Field Station, Neston, Wirral, Merseyside, L64 7TE
SUMMARY
Fifty-four rabbits were used for a 6-week feeding experiment on the effects of including 100 p. p .m. of copper in the diet, 52 were used for an experiment of 8 weeks duration using the same inclusion level, and a further 62 were used for a 6-week investigation into the results obtained from the addition of 200 p.p.m. of copper. In all the experiments half the rabbits were fed a basal ration a nd the other half this diet plus the copper. Copper increased growth rate in all three experiments, significantly at the 200 p.p.m. inclusion rate. Examinations of the effects of copper on certain abdominal organs showed that the main result was a thinning of the caecum as indicated by significant reductions in the weight of I-cm lengths in rabbits fed copper in all three experiments and significant reductions in the percentage weights of the caecum in the two experiments in which copper was fed at 100 p.p.m. At 200 p.p .m . copper increased the efficiency of food utilization although not significantly. INTRODUCTION
Many experiments have been conducted showing the beneficial effects on growth obtained by feeding copper to pigs. The basal diet to which the copper is added may affect the response, for Castell & Bowland ( 1968) found that the increased gain and reduced feed per kilogram gain with copper supplements were more apparent when fishmeal rather than soyabean meal and a high rather than a low protein level were fed, and Drouliscos, Bowland & Elliot (1970) recorded that supplemental copper increased rate of gain for pigs on a fishmeal-supplemented diet but not for pigs on a soyabean meal-supplemented ration. A few observations on the response of chicks to dietary copper supplementation have indicated that there may also be a growth stimulating effect in this species. Smith (1969) recorded a non-significant weight gain at 100 p. p.m. and] enkins, Morris & Valmotis (1970) recorded that when the basal diet was composed mainly of wheat and fish meal with added tallow significant growth responses to copper resulted. King ( 1972) found that the weights of the
THE FEEDI G OF COPPER SULPHATE TO GROWING RABBITS
71
small intestine, expressed as percentages of body weight, were significantly rcduced by feeding 100 p.p.m. of copper to chicks of both sexes for a period of 9 wccks. The weights of I-cm lengths of small intestine were also reduced, but not significantly. The caeca weights expressed as a percentage of body weight were increased, but the weights of I-cm lengths of the caeca were reduced . Not one of the differences in the caeca weights was significant. Little information on the copper requirements of rabbits is available, but Quarterman (1967) recommends the inclusion of at least 4 p.p.m. of copper in the dry feed. A hypochromic and microcytic anaemia and hair d epigmentation have been associated with a copper d eficiency in rabbits, but b on e changes, other than fragi lity, are not commonly observed. Rabbits will accumulate copper in the liver when it is given in excessive quantities and they maintain normal health and growth on diets containing 500 p.p.m. copper, despite a fourteenfold increase in liver copper (Quarterman, 1967). The experiments described in this paper were designed to show whether the continuous feeding of copper sulphate accelerated the growth rate of young rabbits, and whether the weights of the liver, stomach, small intestine, and caecu m were affected. MATERIALS AND METHODS
Rabbits In one experiment 106 Californian x New Zealand White rabbits were used, 58 males and 48 females. Litter-mate pairs of the same sex were selected, one of each pair being fed the basal ration (N ) and the second this diet plus 100 p.p .m. added copper (C). Fifty-four of the rabbits were killed after a 6-week feeding period and the other 52 after a feeding period of 8 weeks. All the r abbits were weighed each fortnight. In a second experiment 46 Californian x New Zealand White (22 bucks and 24 does) and 16 Dutch (12 bucks and 4 does) rabbits were divided into two groups similarly but the copper supplemented diet contained 200 p.p.m. of copper. These rabbits were killed after a 6-week feeding period. Housing The rabbits were placed in wire-mesh cages when weaned at about 4 weeks of age a nd fed a proprietary pellet ration for I week so that they became accustomed to the management conditions before the experimental rations were started. Each cage held up to four rabbits, all on the same diet, but in the :xperiment at the 200 p.p.m. copper level not more than three rabbits were kept 111 a cage. Feeding The basal diet throughout consisted of pellets with the following formula: whi te fishmeal I part, grassmeal 2 parts, bran 4 parts, Sussex ground oats I t parts and weatings I! parts. It was fed unsupplemented or with the addition of either 100 p.p.m. or 200 p .p. m. of copper added as copper sulphate
BRITISH VETERINARY JOURNAL,
131 ,
1
(CuS04.5H20). The basal diet had a protein percentage of 18'1 and a copper content of about 10 mg/kg and gave no indication of producing clinical signs of a copper deficiency in the rabbits. The pellets were fed ad libitum and free access to water was allowed. Individual figures for food consumption were not kept, because the rabbits were not housed separately, but the amounts of food consumed by the rabbits in each cage were recorded in the 200-p.p.m. copper experiment. Each rabbit was killed by dislocating its neck, and the post-mortem examination was commenced within 30 min of death. The small intestine and caecum (without the appendix) were measured while lying on a wet, stainless-steel draining board so as to avoid any artificial stretching. The stomach, small intestine, and caecum were then opened and their contents removed under a gentle stream of water. They were allowed to drain for 15 min and then weighed. The liver was placed on a piece of filter paper to remove any exuded blood and then weighed. These operations were performed by one person to eliminate differences in handling techniques. Direct comparisons or organ lengths and weights between treated and untreated pairs could not be made as the rabbits were usually of different body weights, and so, to circumvent the effects of body weights on organ weights, the individual organ weights have been expressed as percentages of body weight, and, in the case of the small intestine and caecum, as the weights of I-cm lengths. The significances of the findings have been determined by the application of the t-test. RESULTS
As shown in Table I the rabbits given the copper fortified ration at the 100 p.p.m. level grew more quickly than the controls after both the feeding periods, although neither of the differences in liveweight increase were significant. Table II gives the findings when 200 p.p.m. of copper were fed and demonstrates a significant growth response. The liver weights, expressed as a percentage of body weight, were slightly decreased when the copper at the lower level was fed for 6 weeks, and slightly increased when fed at this level for 8 weeks and at the higher level. The stomach and small intestine percentage weights and the weights of I-cm lengths of small intestine were increased by copper at 100 p.p.m. after · 6 weeks feeding and reduced after 8 weeks feeding at this level and at the 200 p.p.m. level. These results were not significant. The corresponding figures for the caecum show that in all three experiments copper significantly reduced the weight of I -cm lengths and also reduced the percentage weights in the three investigations, significantly in the two feeding periods at the 100 p.p.m. inclusion rate. The average food conversion ratios for the rabbits on the 200 p.p.m. copper level experiment, which were kept in twos or threes in cages, are shown in Table II. Those receiving the copper utilized their food more efficiently, but the differences between the two groups were not significant.
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TABLE I THE 52
AVE R AGE L I VE - WE I G H T GA I NS AN D ORGAN WE I GHTS OF 54 R ABB I TS KILLED A F T E R A 6 - W EE K F E EDIN G PERIOD AND K I LLE D AFTE R AN 8-WEEK FEE DI NG PER I OD . HALF T H E RABB I TS I N EACH AGE G R O U P WE R E FE D ON THE BASAL RAT I ON
(N )
AND THE OT H E R
HALF WE R E FED THE R ATION SUPPLEMENTED WITH
100
Average live weight increase (g) O rgan weights Liver (%wt. ) Stomach ( %wt. ) Small intestine (SI) ( %wt. ) Caecum ( % wt.) SI weight of I cm length (g) Caecum weigh t of I cm length (g)
*P
....j
- 0-092 - 0- 108**
± 0'067°
+ 27'4 6
'"ti
::r::
± 0' 137 8 ± 0 ' 2 12 1 ± 0 -07 1 4
+ 0'002 - 0 - 108*
± 0 -0458
+ 0.00 1 - 0 -0 7 5*
± 0 -0349 ± 0-030 3
3 . 68 3 0-8 33 1 -95 8 0-86 1 0' 11 8 0-55 2
3- 608 0 -8 4 1 2 -0 5 0 0-9 6 9 0' 12 3 0 -628
- 0'005
± 0-0374 ± 0 -0047
- 0'°76 **
± 0-0225
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BRITISH VETERINARY JOURNAL,
74
13 I,
I
TABLE II THE AVERAGE LIVE-WEIGHT GAINS AND ORGAN WEIGHTS OF 62
RABBITS KILLED
AFTER A
6-WEEK FEEDING PERIOD. HALF THE RA B BITS WERE F E D ON THE BASAL
RATION
(N )
AND
THE
OTHER
HALF
WERE
WITH 200 P.P.M.
FED
C Average live-weight increase (g) Organ weights Liver ( %wt. ) Stomach ( % wt. ) Small Intestine (SI) ( %wt.) Caecum ( % wt. ) S.1. weight of I cm length (g) Caecum weight of I cm length (g) Food consumed (g) per I g live-weight increase
*p
THE FEEDING OF COPPER SULPHATE TO GROWING RABBITS By]. O. L. KING Veterinary Field Station, Neston, Wirral, Merseyside, L64 7TE
SUMMARY
Fifty-four rabbits were used for a 6-week feeding experiment on the effects of including 100 p. p .m. of copper in the diet, 52 were used for an experiment of 8 weeks duration using the same inclusion level, and a further 62 were used for a 6-week investigation into the results obtained from the addition of 200 p.p.m. of copper. In all the experiments half the rabbits were fed a basal ration a nd the other half this diet plus the copper. Copper increased growth rate in all three experiments, significantly at the 200 p.p.m. inclusion rate. Examinations of the effects of copper on certain abdominal organs showed that the main result was a thinning of the caecum as indicated by significant reductions in the weight of I-cm lengths in rabbits fed copper in all three experiments and significant reductions in the percentage weights of the caecum in the two experiments in which copper was fed at 100 p.p.m. At 200 p.p .m . copper increased the efficiency of food utilization although not significantly. INTRODUCTION
Many experiments have been conducted showing the beneficial effects on growth obtained by feeding copper to pigs. The basal diet to which the copper is added may affect the response, for Castell & Bowland ( 1968) found that the increased gain and reduced feed per kilogram gain with copper supplements were more apparent when fishmeal rather than soyabean meal and a high rather than a low protein level were fed, and Drouliscos, Bowland & Elliot (1970) recorded that supplemental copper increased rate of gain for pigs on a fishmeal-supplemented diet but not for pigs on a soyabean meal-supplemented ration. A few observations on the response of chicks to dietary copper supplementation have indicated that there may also be a growth stimulating effect in this species. Smith (1969) recorded a non-significant weight gain at 100 p. p.m. and] enkins, Morris & Valmotis (1970) recorded that when the basal diet was composed mainly of wheat and fish meal with added tallow significant growth responses to copper resulted. King ( 1972) found that the weights of the
THE FEEDI G OF COPPER SULPHATE TO GROWING RABBITS
71
small intestine, expressed as percentages of body weight, were significantly rcduced by feeding 100 p.p.m. of copper to chicks of both sexes for a period of 9 wccks. The weights of I-cm lengths of small intestine were also reduced, but not significantly. The caeca weights expressed as a percentage of body weight were increased, but the weights of I-cm lengths of the caeca were reduced . Not one of the differences in the caeca weights was significant. Little information on the copper requirements of rabbits is available, but Quarterman (1967) recommends the inclusion of at least 4 p.p.m. of copper in the dry feed. A hypochromic and microcytic anaemia and hair d epigmentation have been associated with a copper d eficiency in rabbits, but b on e changes, other than fragi lity, are not commonly observed. Rabbits will accumulate copper in the liver when it is given in excessive quantities and they maintain normal health and growth on diets containing 500 p.p.m. copper, despite a fourteenfold increase in liver copper (Quarterman, 1967). The experiments described in this paper were designed to show whether the continuous feeding of copper sulphate accelerated the growth rate of young rabbits, and whether the weights of the liver, stomach, small intestine, and caecu m were affected. MATERIALS AND METHODS
Rabbits In one experiment 106 Californian x New Zealand White rabbits were used, 58 males and 48 females. Litter-mate pairs of the same sex were selected, one of each pair being fed the basal ration (N ) and the second this diet plus 100 p.p .m. added copper (C). Fifty-four of the rabbits were killed after a 6-week feeding period and the other 52 after a feeding period of 8 weeks. All the r abbits were weighed each fortnight. In a second experiment 46 Californian x New Zealand White (22 bucks and 24 does) and 16 Dutch (12 bucks and 4 does) rabbits were divided into two groups similarly but the copper supplemented diet contained 200 p.p.m. of copper. These rabbits were killed after a 6-week feeding period. Housing The rabbits were placed in wire-mesh cages when weaned at about 4 weeks of age a nd fed a proprietary pellet ration for I week so that they became accustomed to the management conditions before the experimental rations were started. Each cage held up to four rabbits, all on the same diet, but in the :xperiment at the 200 p.p.m. copper level not more than three rabbits were kept 111 a cage. Feeding The basal diet throughout consisted of pellets with the following formula: whi te fishmeal I part, grassmeal 2 parts, bran 4 parts, Sussex ground oats I t parts and weatings I! parts. It was fed unsupplemented or with the addition of either 100 p.p.m. or 200 p .p. m. of copper added as copper sulphate
BRITISH VETERINARY JOURNAL,
131 ,
1
(CuS04.5H20). The basal diet had a protein percentage of 18'1 and a copper content of about 10 mg/kg and gave no indication of producing clinical signs of a copper deficiency in the rabbits. The pellets were fed ad libitum and free access to water was allowed. Individual figures for food consumption were not kept, because the rabbits were not housed separately, but the amounts of food consumed by the rabbits in each cage were recorded in the 200-p.p.m. copper experiment. Each rabbit was killed by dislocating its neck, and the post-mortem examination was commenced within 30 min of death. The small intestine and caecum (without the appendix) were measured while lying on a wet, stainless-steel draining board so as to avoid any artificial stretching. The stomach, small intestine, and caecum were then opened and their contents removed under a gentle stream of water. They were allowed to drain for 15 min and then weighed. The liver was placed on a piece of filter paper to remove any exuded blood and then weighed. These operations were performed by one person to eliminate differences in handling techniques. Direct comparisons or organ lengths and weights between treated and untreated pairs could not be made as the rabbits were usually of different body weights, and so, to circumvent the effects of body weights on organ weights, the individual organ weights have been expressed as percentages of body weight, and, in the case of the small intestine and caecum, as the weights of I-cm lengths. The significances of the findings have been determined by the application of the t-test. RESULTS
As shown in Table I the rabbits given the copper fortified ration at the 100 p.p.m. level grew more quickly than the controls after both the feeding periods, although neither of the differences in liveweight increase were significant. Table II gives the findings when 200 p.p.m. of copper were fed and demonstrates a significant growth response. The liver weights, expressed as a percentage of body weight, were slightly decreased when the copper at the lower level was fed for 6 weeks, and slightly increased when fed at this level for 8 weeks and at the higher level. The stomach and small intestine percentage weights and the weights of I-cm lengths of small intestine were increased by copper at 100 p.p.m. after · 6 weeks feeding and reduced after 8 weeks feeding at this level and at the 200 p.p.m. level. These results were not significant. The corresponding figures for the caecum show that in all three experiments copper significantly reduced the weight of I -cm lengths and also reduced the percentage weights in the three investigations, significantly in the two feeding periods at the 100 p.p.m. inclusion rate. The average food conversion ratios for the rabbits on the 200 p.p.m. copper level experiment, which were kept in twos or threes in cages, are shown in Table II. Those receiving the copper utilized their food more efficiently, but the differences between the two groups were not significant.
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TABLE I THE 52
AVE R AGE L I VE - WE I G H T GA I NS AN D ORGAN WE I GHTS OF 54 R ABB I TS KILLED A F T E R A 6 - W EE K F E EDIN G PERIOD AND K I LLE D AFTE R AN 8-WEEK FEE DI NG PER I OD . HALF T H E RABB I TS I N EACH AGE G R O U P WE R E FE D ON THE BASAL RAT I ON
(N )
AND THE OT H E R
HALF WE R E FED THE R ATION SUPPLEMENTED WITH
100
Average live weight increase (g) O rgan weights Liver (%wt. ) Stomach ( %wt. ) Small intestine (SI) ( %wt. ) Caecum ( % wt.) SI weight of I cm length (g) Caecum weigh t of I cm length (g)
*P
....j
- 0-092 - 0- 108**
± 0'067°
+ 27'4 6
'"ti
::r::
± 0' 137 8 ± 0 ' 2 12 1 ± 0 -07 1 4
+ 0'002 - 0 - 108*
± 0 -0458
+ 0.00 1 - 0 -0 7 5*
± 0 -0349 ± 0-030 3
3 . 68 3 0-8 33 1 -95 8 0-86 1 0' 11 8 0-55 2
3- 608 0 -8 4 1 2 -0 5 0 0-9 6 9 0' 12 3 0 -628
- 0'005
± 0-0374 ± 0 -0047
- 0'°76 **
± 0-0225
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BRITISH VETERINARY JOURNAL,
74
13 I,
I
TABLE II THE AVERAGE LIVE-WEIGHT GAINS AND ORGAN WEIGHTS OF 62
RABBITS KILLED
AFTER A
6-WEEK FEEDING PERIOD. HALF THE RA B BITS WERE F E D ON THE BASAL
RATION
(N )
AND
THE
OTHER
HALF
WERE
WITH 200 P.P.M.
FED
C Average live-weight increase (g) Organ weights Liver ( %wt. ) Stomach ( % wt. ) Small Intestine (SI) ( %wt.) Caecum ( % wt. ) S.1. weight of I cm length (g) Caecum weight of I cm length (g) Food consumed (g) per I g live-weight increase
*p
