Br. vet . j (1992) . 148, 23
PULMONARY MECHANICS MEASUREMENTS IN NORMAL CALVES
D . D . S . COLLIE Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, Veterinary Field Station, Easter Bush, Roslin, Midlothian EH25 9RG
SUMMARY The mechanics of ventilation were assessed in 25 normal conscious crossbred calves and immature cattle, aged 24-406 days and weighing 60-360 kg . An oesophageal balloon was used to measure transpulmonary pressure and a pneumotachograph attached to a face mask measured respiratory flows . A regression analysis with body weight as the independent variable and pulmonary function values as the dependent variables demonstrated growth related changes in pulmonary function, confirming those previously described . Mean pulmonary function values differed in a number of respects from previously reported values for cattle of similar size . The response of individual cattle to the pulmonary function testing procedure probably accounted for a major part of these differences .
INTRODUCTION In humans, a variety of methods are available for evaluating pulmonary function (West, 1987), and many are of established value for the routine assessment of lung function in health and disease . However, most of these methods require cooperation from the subject and as such are not readily applicable to the evaluation of pulmonary function in the domestic species . As a result, until recently, limited information has been available concerning the evaluation of pulmonary function of domestic animals . Techniques for studying the mechanics of human pulmonary function have now been adapted and modified for use in conscious, unsedated domestic animals . Within ruminants, such techniques have been applied to goats (Bakima et al., 1988, 1990), sheep (Wanner & Reinhart, 1978 ; von Zipfel et al., 1987) and cattle (Kiorpes et al., 1978 ; Musewe et al., 1979 ; Lekeux et al., 1984a, h, 1985 ; Gustin et al., 1988 ; Gallivan & McDonell, 1988 ; Gallivan et al., 1989) . It is well recognized in humans (Wanner, 1980) that the variability of certain indicators of pulmonary function in and between individuals is considerable . Similar findings have been reported in cattle (Kiorpes et al., 1978 ; Gallivan & McDonell, 1988) and goats (Bakima et al., 1988) . The consequence of this large inter- and intrasubject variability of routine pulmonary function measurements, together with variable methodology used by different research workers has led to
24
BRITISH VETERINARY JOURNAL . 148, 1
the relatively wide range of normal values reported for pulmonary mechanics parameters in the horse and cow . In calves and young cattle, normal values for pulmonary mechanics variables have been reported for the Dutch and Holstein-Friesian breeds (Kiorpes et al., 1978 ; Lekeux et al., 1984a) and for the Belgian White and Blue double-muscled breed (Gustin et al., 1988) . The range of normal values reported for these breeds is considerable . Since no data exist concerning the mechanics of ventilation of cattle of other breeds it was considered appropriate to establish reference values for pulmonary mechanics measurements in a range of breeds and crosses . This would, in future, allow the pulmonary function of field cases of young cattle with respiratory disease to be assessed in relation to normal animals of similar age, breed and conformation .
MATERIALS AND METHODS
Animals Twenty-five crossbred animals aged between 24 and 387 days (d) and weighing 60-360 kg were used . All animals were found to be healthy on the basis of clinical examination . Animals were divided into the following three groups according to body weight (BW) and age : group A, 60-65 kg, 24-51 d; group B, 137-180 kg, 137-163 d ; group C, 215-360 kg, 239-406 d .
Methods Young calves were restrained within a wooden crate and older animals were restrained within a purpose-built crush . Animals were allowed to adapt to the environment of the pulmonary function laboratory over a period of at least 1 h prior to commencement of pulmonary function testing and had previously been exposed to this environment several times during the preceding weeks . Measurements were performed at an altitude of 180 m . No sedation was required prior to or during the procedure . Measurement of oesophageal pressure was performed using a balloon placed in the oesophagus . The oesophageal balloon (length 15 cm, diameter 1 .5 cm) was sealed over the end of a 190 cm polyethylene catheter (3 mm internal diameter, 4.5 mm external diameter) which had a number of holes cut in a spiral manner in the end covered by the balloon . The balloon-catheter assembly was passed via the nares so that it came to lie within the oesophagus . The position within the oesophagus was determined by applying the regression equation developed by Lekeux et al. (1984c) which relates thoracic perimeter (TP) to the optimal position of the balloon within the oesophagus in Friesian cattle . After insertion, air was evacuated from the balloon and a small volume (1 nil) replaced . The free end of the oesophageal catheter was connected to a differential pressure transducer (Mercurtiy CS9, Mercury Electronics (Scotland) Ltd) . The other side of the transducer was connected via identical tubing to an aperture in the mask directly above the nares . Transpulmonary pressure (Pt,,) was defined as the difference between mask pressure and oesophageal pressure .
PULMONARY MEASUREMENTS IN NORMAL CALVES
25
Fibreglass masks were moulded using the muzzles of cadavers of similar size and conformation to the animals being studied . They were sealed to the face by means of a rubber collar, and the dead space of the mask, measured by water displacement with the mask in place on selected cadavers, did not exceed 25% of the anticipated tidal volume (VT) . Animals were allowed an adaptation period of 5 min with the mask and catheters in place prior to any measurements being made . Airflow was measured by connecting a pneumotachograph of the appropriate size (F300L : Mercury Electronics (Scotland) Ltd or Fleisch : Numbers 2 & 4) to the mask aperture . The pressure drop across the pneumotachograph was measured using a sensitive differential pressure transducer (CS9 : Mercury Electronics (Scotland) Ltd) . At the time of measurement, pressure and flow signals from both transducers were visualized on an X-Y oscilloscope (Gould OS300 : Gould Electronics Ltd, England) and then permanently recorded on videotape after being digitized by a pulse code modulator (Sony PCM701-ES : Sony', Japan) . Playback of collected data onto a chart recorder (Multirace 8 : Lectromed UK Ltd) allowed electronic integration of the flow signal to give a volume readout and selection of breaths suitable for analysis . Calibration of the pneumotachograph for flow was achieved by using a Rotameter flow meter (Rotameter 2000 : G.E .C . Elliot, Process Instruments Ltd, Croydon) and volume was checked by means of a calibrated 2-L syringe . The pressure transducer was calibrated against a water manometer . The frequency response characteristics of the flow and pressure recording systems were matched up to 5 Hz using standard techniques (Macklem, 1974) . Arterial blood was sampled from the brachial artery using the method described by Fisher et al. (1980) . Volumes of 2 ml blood were collected anaerobically into heparinized glass syringes with metal stirrers and syringes were then immediately placed on crushed ice . Blood was mixed gently every few minutes until analysis was completed within 1 h of collection . Analysis was performed at 37° C using a blood gas analyser (Corning 168 : Corning Medical) . Values of Pao 2 , Paco,,, pH and HCO were corrected for rectal temperature (Kelman & Nunn, 1966) . Analysis From the data collected from each animal, five successive breaths, free from artefact or disturbance, were selected for analysis . The following indicators of pulmonary function were calculated : respiratory frequency (f ), mean inspiratory and expiratory flow (mVI, mVE), maximal inspiratory and expiratory flow (VEmax, VEmax), tidal volume (V,,), minute ventilation (Ve ), minimum and maximum transpulmonary pressure (Ppl, ;,,, Ppl, nax ), maximum change in transpulmonary pressure (maxdPpl), Ppl at functional residual capacity (Ppl fr,), dynamic compliance (C,,, .,,), pulmonary flow-resistance (R1%, REy ) at 25, 50 and 75% of inspiration and expiration, `average' pulmonary flow resistance (R1 ,), viscous work of breathing (W, 1 ) and power of breathing (W,.;,/min) . Dynamic compliance was calculated as the ratio of volume change to transpulmonary pressure change between points of zero flow (Krieger, 1963) with correction made for the effects of inertance, as described by Lekeux et al . (1988) . Resistance was calculated using two methods . In the first, the instantaneous flow rates at
26
BRITISH VETERINARY JOURNAL, 148, 1
25, 50 and 75% of inspiration and expiration were divided by the difference between the measured transpulmonary pressures at these points and that which is required to overcome elastic forces . In the second, the change in transpulmonary pressure between two `isovolume' points in inspiration and expiration was divided by the corresponding change in flows between these two points (Frank et aL, 1957) . Work of breathing parameters was measured by planimetry of the area of pressure-volume loops (Krieger, 1963) . Student's t-test was used to analyse differences for pulmonary function variables between groups A, B and C . RI % and RE % values within groups were compared using paired t-tests . Linear, polynomial of the 2nd and 3rd degree and allometric regression equations were calculated to relate selected pulmonary function variables to body weight .
RESULTS Mean values for pulmonary function variables measured in this study and in previous studies (Kiorpes et aL, 1978 ; Lekeux et al., 1984b) are presented in Tables I and II respectively. The significance of differences between the means of groups A, B and C are also shown in Table I . MaxdPpl, VImax, VEmax, mVI, mVE, V T , Ve , Cdyn, Weis and Wes/min values for calves of groups B and C are significantly greater than those for group A calves . Vlmax, mVI, mVE and V e values for calves of group C are significantly greater than those for group B calves . No significant differences in resistance values were detected between groups A and B ; however, RL, R 1% and RE% values for group C calves were significantly less than group A calves and R I, and R, % values for group C calves were significantly less than those for group B calves . Pplmin and Ppl frc values for group B and C calves were significantly less than those for group A calves. No significant differences between groups for Pao 2 or Paco 2 were observed, the pooled mean (±standard error) values for all calves for Pao2 and Paco2i were 11 .55±0.16 and 4 .69±0.13 respectively. Within groups there were no significant changes in R I% or RE % at different lung volumes as determined by paired t-tests . The most statistically significant equations selected from the regression analyses are shown in Table III together with the variance ratio (F), the determination coefficient (r 2 ) and degree of significance of the variance ratio . These equations show that maxdPpl, mVI, mVE, VEmax, VEmax, VT , Ve , C d,, W;, and W, i,/min increase with somatic growth and Pplmin, Pplfre and RL decrease with somatic growth . Growth related changes in V T and Ve are illustrated in Fig . 1 .
DISCUSSION Comparison of the data generated in this study with previously reported pulmonary function values for calves of similar age but different breeds (Bisgard et al., 1973 ; Kiorpes et al., 1978 ; Lekeux et al., 1984b ; Gustin et al., 1988) reveals some distinct differences . Values for inspiratory and expiratory flows, the flow related parameters VT and Ve , and for W vi„ W,. i,/min and RL for group A calves are greater than previously reported values for calves of similar size (Table II) . C dr.,, was similar
PULMONARY MEASUREMENTS IN NORMAL CALVES
27
Table I Calf pulmonary function values for the present study Variable Age (d) BW (kg) TP (cm) f (min - ') Pplmi „ ( kPa) Pplmaz (kPa) maxdPpl (kPa) Ppl f„ ( kPa) mVl (1/s) mVE (1/s) Vlmax (1/s) VEmax (1/s) VT (1) V,, (1/min) C d,- (1/kPa) Rin (kPa /1/s) R150 (kPa /1 /s) R 17 , (kPa /l/s) RE25 (kPa/1 /s) R050 (kPa /1 /s) RETS (kPa/l/s) R L (kPa /1 /s) W, ;, U) „i,/min (J/min) Pao_> (kPa) Paco 2 (kPa)
Group A 40±3 63 .6±0 .6 91 .8±0 .8 40 .1±2 .8 -0 .81±0.02 -0 .03±0 .03 0 .84±0.02 -0 .17±0 .03 0 .94±0 .09 0 .85±0 .11 1 .22±0.12 1 .59±0 .19 0 .65±0.03 28 .12±2 .81 1 .43±0 .10 0 .28±0 .05 0 .37±0.06 0 .40±0 .06 0 .28±0 .05 0 .31±0 .05 0,34±0 .05 0 .43±0 .07 0 .35±0 .03 14 .0±0 .9 10 .91±0 .34 4 .84±0 .37
Group B 156±3** 166 .9±5 .1** 126 .6±0 .9** 28 .9±1 .9** -1 .74±0 .23** NS -0 .03±0 .08 1 .79±0 .28* -0 .53±0 .05** 1 .65±0 .07** 1 .59±0 .06** 2 .22±0 .07** 2 .52±0 .12** 1 .78±0 .09** 51 .90±3 .02** 7 .85±1 .33** 0 .30±0 .04Ns NS 0 .39±0 .04 0 .46±0 .06Ns 0 .19±0 .04Ns NS 0 .22±0 .05 0 .28±0 .06Ns N5 0 .39±0 .06 1 .68±0 .29** 48 .6±4 .6** NS 9 .89±0 .27 5 .22±0 .01 Ns
Group C 313±24**/** 291 .9±17 .0**/** 152 .9±3 .5**'** 37 .0±2 .9 NS/ * -1 .71±0 .17 ** RNs NS/NS -0 .34±0 .14 */NS 1 .47±0 .12 * /Ns -0 .80±0 .12 ** 2 .63±0 .26**'** 2 .22±0 .21** / * 3 .10±0 .28**/* */NS 2 .93±0 .21 * /NS 2 .02±0 .12** 75 .18±1 .83**'* *RNs 7 .96±1 .43 * 0 .16±0 .02* / * 0 .19±0 .02*'** 0 .22±0 .03* i ** *' NS 0 .13±0 .02 */NS 0 .16±0 .02 Ns 0 .18±0 .02*, 0 .22±0 .03 * 7 * */NS 1 .68±0 .34* s " .3 ** 62 .2±8 N S iNS 11 .40±0 .51 NS / Ns 4 .67±0 .15
Calves were grouped according to body weight and age . Figures shown are mean±standard error . Significance of differences between the means of groups are shown in order in superscript, i .e . for group B variables (A/B) and group C variables (A/C, B/C) . **P
PULMONARY MECHANICS MEASUREMENTS IN NORMAL CALVES
D . D . S . COLLIE Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, Veterinary Field Station, Easter Bush, Roslin, Midlothian EH25 9RG
SUMMARY The mechanics of ventilation were assessed in 25 normal conscious crossbred calves and immature cattle, aged 24-406 days and weighing 60-360 kg . An oesophageal balloon was used to measure transpulmonary pressure and a pneumotachograph attached to a face mask measured respiratory flows . A regression analysis with body weight as the independent variable and pulmonary function values as the dependent variables demonstrated growth related changes in pulmonary function, confirming those previously described . Mean pulmonary function values differed in a number of respects from previously reported values for cattle of similar size . The response of individual cattle to the pulmonary function testing procedure probably accounted for a major part of these differences .
INTRODUCTION In humans, a variety of methods are available for evaluating pulmonary function (West, 1987), and many are of established value for the routine assessment of lung function in health and disease . However, most of these methods require cooperation from the subject and as such are not readily applicable to the evaluation of pulmonary function in the domestic species . As a result, until recently, limited information has been available concerning the evaluation of pulmonary function of domestic animals . Techniques for studying the mechanics of human pulmonary function have now been adapted and modified for use in conscious, unsedated domestic animals . Within ruminants, such techniques have been applied to goats (Bakima et al., 1988, 1990), sheep (Wanner & Reinhart, 1978 ; von Zipfel et al., 1987) and cattle (Kiorpes et al., 1978 ; Musewe et al., 1979 ; Lekeux et al., 1984a, h, 1985 ; Gustin et al., 1988 ; Gallivan & McDonell, 1988 ; Gallivan et al., 1989) . It is well recognized in humans (Wanner, 1980) that the variability of certain indicators of pulmonary function in and between individuals is considerable . Similar findings have been reported in cattle (Kiorpes et al., 1978 ; Gallivan & McDonell, 1988) and goats (Bakima et al., 1988) . The consequence of this large inter- and intrasubject variability of routine pulmonary function measurements, together with variable methodology used by different research workers has led to
24
BRITISH VETERINARY JOURNAL . 148, 1
the relatively wide range of normal values reported for pulmonary mechanics parameters in the horse and cow . In calves and young cattle, normal values for pulmonary mechanics variables have been reported for the Dutch and Holstein-Friesian breeds (Kiorpes et al., 1978 ; Lekeux et al., 1984a) and for the Belgian White and Blue double-muscled breed (Gustin et al., 1988) . The range of normal values reported for these breeds is considerable . Since no data exist concerning the mechanics of ventilation of cattle of other breeds it was considered appropriate to establish reference values for pulmonary mechanics measurements in a range of breeds and crosses . This would, in future, allow the pulmonary function of field cases of young cattle with respiratory disease to be assessed in relation to normal animals of similar age, breed and conformation .
MATERIALS AND METHODS
Animals Twenty-five crossbred animals aged between 24 and 387 days (d) and weighing 60-360 kg were used . All animals were found to be healthy on the basis of clinical examination . Animals were divided into the following three groups according to body weight (BW) and age : group A, 60-65 kg, 24-51 d; group B, 137-180 kg, 137-163 d ; group C, 215-360 kg, 239-406 d .
Methods Young calves were restrained within a wooden crate and older animals were restrained within a purpose-built crush . Animals were allowed to adapt to the environment of the pulmonary function laboratory over a period of at least 1 h prior to commencement of pulmonary function testing and had previously been exposed to this environment several times during the preceding weeks . Measurements were performed at an altitude of 180 m . No sedation was required prior to or during the procedure . Measurement of oesophageal pressure was performed using a balloon placed in the oesophagus . The oesophageal balloon (length 15 cm, diameter 1 .5 cm) was sealed over the end of a 190 cm polyethylene catheter (3 mm internal diameter, 4.5 mm external diameter) which had a number of holes cut in a spiral manner in the end covered by the balloon . The balloon-catheter assembly was passed via the nares so that it came to lie within the oesophagus . The position within the oesophagus was determined by applying the regression equation developed by Lekeux et al. (1984c) which relates thoracic perimeter (TP) to the optimal position of the balloon within the oesophagus in Friesian cattle . After insertion, air was evacuated from the balloon and a small volume (1 nil) replaced . The free end of the oesophageal catheter was connected to a differential pressure transducer (Mercurtiy CS9, Mercury Electronics (Scotland) Ltd) . The other side of the transducer was connected via identical tubing to an aperture in the mask directly above the nares . Transpulmonary pressure (Pt,,) was defined as the difference between mask pressure and oesophageal pressure .
PULMONARY MEASUREMENTS IN NORMAL CALVES
25
Fibreglass masks were moulded using the muzzles of cadavers of similar size and conformation to the animals being studied . They were sealed to the face by means of a rubber collar, and the dead space of the mask, measured by water displacement with the mask in place on selected cadavers, did not exceed 25% of the anticipated tidal volume (VT) . Animals were allowed an adaptation period of 5 min with the mask and catheters in place prior to any measurements being made . Airflow was measured by connecting a pneumotachograph of the appropriate size (F300L : Mercury Electronics (Scotland) Ltd or Fleisch : Numbers 2 & 4) to the mask aperture . The pressure drop across the pneumotachograph was measured using a sensitive differential pressure transducer (CS9 : Mercury Electronics (Scotland) Ltd) . At the time of measurement, pressure and flow signals from both transducers were visualized on an X-Y oscilloscope (Gould OS300 : Gould Electronics Ltd, England) and then permanently recorded on videotape after being digitized by a pulse code modulator (Sony PCM701-ES : Sony', Japan) . Playback of collected data onto a chart recorder (Multirace 8 : Lectromed UK Ltd) allowed electronic integration of the flow signal to give a volume readout and selection of breaths suitable for analysis . Calibration of the pneumotachograph for flow was achieved by using a Rotameter flow meter (Rotameter 2000 : G.E .C . Elliot, Process Instruments Ltd, Croydon) and volume was checked by means of a calibrated 2-L syringe . The pressure transducer was calibrated against a water manometer . The frequency response characteristics of the flow and pressure recording systems were matched up to 5 Hz using standard techniques (Macklem, 1974) . Arterial blood was sampled from the brachial artery using the method described by Fisher et al. (1980) . Volumes of 2 ml blood were collected anaerobically into heparinized glass syringes with metal stirrers and syringes were then immediately placed on crushed ice . Blood was mixed gently every few minutes until analysis was completed within 1 h of collection . Analysis was performed at 37° C using a blood gas analyser (Corning 168 : Corning Medical) . Values of Pao 2 , Paco,,, pH and HCO were corrected for rectal temperature (Kelman & Nunn, 1966) . Analysis From the data collected from each animal, five successive breaths, free from artefact or disturbance, were selected for analysis . The following indicators of pulmonary function were calculated : respiratory frequency (f ), mean inspiratory and expiratory flow (mVI, mVE), maximal inspiratory and expiratory flow (VEmax, VEmax), tidal volume (V,,), minute ventilation (Ve ), minimum and maximum transpulmonary pressure (Ppl, ;,,, Ppl, nax ), maximum change in transpulmonary pressure (maxdPpl), Ppl at functional residual capacity (Ppl fr,), dynamic compliance (C,,, .,,), pulmonary flow-resistance (R1%, REy ) at 25, 50 and 75% of inspiration and expiration, `average' pulmonary flow resistance (R1 ,), viscous work of breathing (W, 1 ) and power of breathing (W,.;,/min) . Dynamic compliance was calculated as the ratio of volume change to transpulmonary pressure change between points of zero flow (Krieger, 1963) with correction made for the effects of inertance, as described by Lekeux et al . (1988) . Resistance was calculated using two methods . In the first, the instantaneous flow rates at
26
BRITISH VETERINARY JOURNAL, 148, 1
25, 50 and 75% of inspiration and expiration were divided by the difference between the measured transpulmonary pressures at these points and that which is required to overcome elastic forces . In the second, the change in transpulmonary pressure between two `isovolume' points in inspiration and expiration was divided by the corresponding change in flows between these two points (Frank et aL, 1957) . Work of breathing parameters was measured by planimetry of the area of pressure-volume loops (Krieger, 1963) . Student's t-test was used to analyse differences for pulmonary function variables between groups A, B and C . RI % and RE % values within groups were compared using paired t-tests . Linear, polynomial of the 2nd and 3rd degree and allometric regression equations were calculated to relate selected pulmonary function variables to body weight .
RESULTS Mean values for pulmonary function variables measured in this study and in previous studies (Kiorpes et aL, 1978 ; Lekeux et al., 1984b) are presented in Tables I and II respectively. The significance of differences between the means of groups A, B and C are also shown in Table I . MaxdPpl, VImax, VEmax, mVI, mVE, V T , Ve , Cdyn, Weis and Wes/min values for calves of groups B and C are significantly greater than those for group A calves . Vlmax, mVI, mVE and V e values for calves of group C are significantly greater than those for group B calves . No significant differences in resistance values were detected between groups A and B ; however, RL, R 1% and RE% values for group C calves were significantly less than group A calves and R I, and R, % values for group C calves were significantly less than those for group B calves . Pplmin and Ppl frc values for group B and C calves were significantly less than those for group A calves. No significant differences between groups for Pao 2 or Paco 2 were observed, the pooled mean (±standard error) values for all calves for Pao2 and Paco2i were 11 .55±0.16 and 4 .69±0.13 respectively. Within groups there were no significant changes in R I% or RE % at different lung volumes as determined by paired t-tests . The most statistically significant equations selected from the regression analyses are shown in Table III together with the variance ratio (F), the determination coefficient (r 2 ) and degree of significance of the variance ratio . These equations show that maxdPpl, mVI, mVE, VEmax, VEmax, VT , Ve , C d,, W;, and W, i,/min increase with somatic growth and Pplmin, Pplfre and RL decrease with somatic growth . Growth related changes in V T and Ve are illustrated in Fig . 1 .
DISCUSSION Comparison of the data generated in this study with previously reported pulmonary function values for calves of similar age but different breeds (Bisgard et al., 1973 ; Kiorpes et al., 1978 ; Lekeux et al., 1984b ; Gustin et al., 1988) reveals some distinct differences . Values for inspiratory and expiratory flows, the flow related parameters VT and Ve , and for W vi„ W,. i,/min and RL for group A calves are greater than previously reported values for calves of similar size (Table II) . C dr.,, was similar
PULMONARY MEASUREMENTS IN NORMAL CALVES
27
Table I Calf pulmonary function values for the present study Variable Age (d) BW (kg) TP (cm) f (min - ') Pplmi „ ( kPa) Pplmaz (kPa) maxdPpl (kPa) Ppl f„ ( kPa) mVl (1/s) mVE (1/s) Vlmax (1/s) VEmax (1/s) VT (1) V,, (1/min) C d,- (1/kPa) Rin (kPa /1/s) R150 (kPa /1 /s) R 17 , (kPa /l/s) RE25 (kPa/1 /s) R050 (kPa /1 /s) RETS (kPa/l/s) R L (kPa /1 /s) W, ;, U) „i,/min (J/min) Pao_> (kPa) Paco 2 (kPa)
Group A 40±3 63 .6±0 .6 91 .8±0 .8 40 .1±2 .8 -0 .81±0.02 -0 .03±0 .03 0 .84±0.02 -0 .17±0 .03 0 .94±0 .09 0 .85±0 .11 1 .22±0.12 1 .59±0 .19 0 .65±0.03 28 .12±2 .81 1 .43±0 .10 0 .28±0 .05 0 .37±0.06 0 .40±0 .06 0 .28±0 .05 0 .31±0 .05 0,34±0 .05 0 .43±0 .07 0 .35±0 .03 14 .0±0 .9 10 .91±0 .34 4 .84±0 .37
Group B 156±3** 166 .9±5 .1** 126 .6±0 .9** 28 .9±1 .9** -1 .74±0 .23** NS -0 .03±0 .08 1 .79±0 .28* -0 .53±0 .05** 1 .65±0 .07** 1 .59±0 .06** 2 .22±0 .07** 2 .52±0 .12** 1 .78±0 .09** 51 .90±3 .02** 7 .85±1 .33** 0 .30±0 .04Ns NS 0 .39±0 .04 0 .46±0 .06Ns 0 .19±0 .04Ns NS 0 .22±0 .05 0 .28±0 .06Ns N5 0 .39±0 .06 1 .68±0 .29** 48 .6±4 .6** NS 9 .89±0 .27 5 .22±0 .01 Ns
Group C 313±24**/** 291 .9±17 .0**/** 152 .9±3 .5**'** 37 .0±2 .9 NS/ * -1 .71±0 .17 ** RNs NS/NS -0 .34±0 .14 */NS 1 .47±0 .12 * /Ns -0 .80±0 .12 ** 2 .63±0 .26**'** 2 .22±0 .21** / * 3 .10±0 .28**/* */NS 2 .93±0 .21 * /NS 2 .02±0 .12** 75 .18±1 .83**'* *RNs 7 .96±1 .43 * 0 .16±0 .02* / * 0 .19±0 .02*'** 0 .22±0 .03* i ** *' NS 0 .13±0 .02 */NS 0 .16±0 .02 Ns 0 .18±0 .02*, 0 .22±0 .03 * 7 * */NS 1 .68±0 .34* s " .3 ** 62 .2±8 N S iNS 11 .40±0 .51 NS / Ns 4 .67±0 .15
Calves were grouped according to body weight and age . Figures shown are mean±standard error . Significance of differences between the means of groups are shown in order in superscript, i .e . for group B variables (A/B) and group C variables (A/C, B/C) . **P
