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Influence of Heating on Nutritive Value of Alfalfa-Bromegrass Hay for Sheep
Influence of Heating on Nutritive Value of Alfalfa-Bromegrass Hay for Sheep Y. Y U , G. K. MACLEOD, J. B. STONE, and D. G. G R I E V E Department of Animal and Poultry Science University of Guelph Guelph, Ontario N1G 2W1 ABSTRACT
Alfalfa-bromegrass hay was heated at 90 C for 0, 8, 16, 24, 32, 40, 48, or 56 h. Heating had no clear effect on chemical composition, in vitro rumen digestion, voluntary intake, digestion of major nutrients, and nitrogen retention in sheep. Digestibility of acid-detergent insoluble nitrogen was reduced linearly with heating. Nitrogen utilization of heated hay was not improved significantly by reduced nitrogen excretion in urine and increased nitrogen retention. INTRODUCTION
Proper amount of heating of soybean meal reduced protein solubility, rumen ammonia production, and improved nitrogen (N) utilization (4, 9). However, heating of high-moisture feed such as alfalfa haylage (47% dry matter) in sealed condition increased acid-detergent insoluble N (ADIN) content, reduced N digestibility, and N retention (13). Whether nitrogen utilization of alfalfa hay can be improved by heating has not been evaluated. The objective of our trial was to evaluate the effect of heating of alfalfa-bromegrass hay on chemical composition, voluntary intake, digestion, and N utilization in sheep. MATERIALS AND METHODS
Second growth alfalfa (Medicago sativa) and bromegrass (Bromus inermis) hay (sun-cured) about 3 cm in length was heated at 90 C for O, 8, 16, 24, 32, 40, 48, or 56 h in a forced-draft oven 1. Equivalent heating units (degree-hours above 35 C) ranged from 0 to 3080. Each hay was mixed and sampled (n=4) for determination of dry matter (DM), proximate analysis constituents (1), neutral-detergent fiber (NDF),
Received March 15, 1977. Model 1207, Hotpack Ltd., Waterloo, Ontario. 1977 J Dairy Sci 60:1436-1439
acid-detergent fiber (ADF), ADIN, acid-pepsin insoluble N (APIN) (5), and in vitro digestion of DM and N (7). Six hays, excluding those heated for 32 and 48 h, were fed to 12 sheep averaging about 42 kg (6 mo old) for two periods (21 days/period). Sheep were reassigned randomly to treatments for the second period. Feces and urine were collected during the last 7 days of each period. Feeding was restricted to 90% of the voluntary intake determined during the first 14 days of each period. Feces were freeze-dried and analyzed for the same variables as for hay. Urine was analyzed for total N (1). Compositional and sheep performance data were analyzed by a stepwise deletion (P = .05) polynomial regression program.
RESULTS A N D DISCUSSION
Heating had no effect (P>.05) on proximate analysis constituents and NDF (Table 1). Similar were (6, 8, 13). Acid-detergent fiber and ADIN decreased linearly (P<.05) with heating while the opposite was apparent for hemicellulose and APIN (Table 1). These trends do not agree with with result of Yu (11) who heated alfalfa hay at 88 C for 0 to 48 h. The ADIN%N content in unheated hay was high relative to 7% for normal forages (10). Thus, some heat damage might have occurred during the haymaking process, and the artificial dry heating produced no further damage. In vitro rumen DM digestion was unaffected (P>.05) by heating, but N digestion increased linearly (P<.01) with heating (Table 1). The positive bl with DM and N digestion suggested that heating produced neither heat damage nor protection for forage protein from rumen microbial degradation. Voluntary intake, digestibility of DM, N, ADF, crude fiber, and N-free-extract were unaffected (P>.05) by heating although b l ' s generally were negative (Table 2). These in vivo data confirmed trends from compositional anal-
1436
TECHNICAL NOTE
143 7
TABLE 1. Effect of dry heating (90 C, 0 to 56 h) on c o m p o s i t i o n and in vitro digestion of alfalfa-grass hay evalu a t e d by regression analysis a.
Item
Unheated hay
Regression with degree-hours>35 C Sig. b b ac r2
Dry matter (DM, %)
93
Chemical composition (% DM) Total nitrogen (N) Crude fiber N free extract Ether extract Neutral-detergent fiber Acid-detergent fiber Hemicellulose Acid-detergent insoluble N (ADIN) ADIN (% N) Acid-pepsin insoluble N (% N)
2.7 36 39 1.3 57 46 11 .335 12.8 26
NS d NS NS NS NS <.05 <.005 <.005 <.01 <.01
.33 -3.74 -1.19 .50 -.23 -13.44 13.20 -.19 -8.81 4.76
In vitro m m e n digestion (%) Dry m a t t e r Nitrogen
39 36
NS < .01
10.45 4.76
.02 .01 .003 .02 .0001 .15 .40 .34 .23 .09
.11 .21
a N = 32. bsig. = significance. Quadratic response was no t significant (P>.05) for all variables. C
Regresmon slope (× 10 -4).
d N S = n o t significant (P>.05).
T A B L E 2. Effect of dry heating (90 C, 0 to 56 h) of alfalfa-grass hay on sheep performance evaluated by regression analysis a. Unheated Item Voluntary intake Actual (kg DMd/day) % Body weight
hay
1.159 2.57
Regression with degree-hours>35 C Sig. b
NS e NS
Apparent digestibility (%) Dry matter Nitrogen (N) Acid-detergent fiber Crude fiber N free extract Ether extract Acid-detergent insoluble N
59.8 68.7 54.7 55.7 64.9 43.0 39.1
NS NS NS NS NS <.025 <.005
Total digestible nutrients (%)
57.6
NS
b ac
-.03 -.02
-2.10 -8.09 -2.84 -6.44 .09 29.93 -25.61 -.97
r2
.001 0
.02 .06 .01 .05 0 .21 .60 .004
aN = 24. bsig. = significance. Quadratic response was n o t significant (P>.05) for all variables. CRegression slope (× 10-"). dDM = dry matter. eNS = n o t significant (P>.05). Journal of Dairy Science Vol. 60, No. 9, 1977
1438
",'U ET AL.
TABLE 3. Effect of dry heating (90 C, 0 to 56 h) of alfalfa-grass hay on nitrogen utilization in sheep evaluated by regression analysisa.
Item
Unheated hay
Regression with degree-hours>35 C Sig.b bl c r2
Nitrogen (N, g/day) Intake Feces Urine Retention
27.5 8.6 19.7 .7
NS d NS <.025 NS
1.50 5.73 -9.99 8.56
.002 .05 .24 .14
NS
42.77
.14
N retention (% N digested)
3.7
a N = 24. bsig. = significance. Quadratic response was not significant (P>.05) for all variables. CRegression slope (X 10-4).
dNS = not significant (P>.05).
ysis and in vitro digestion that hays were n o t damaged by heating, b u t the general relationship between digestibility and laboratory measurements was different from that of heated haylages (12, 13). Ether extract digestibility increased linearly (P<.025) with heating (Table 2) and was in accordance with (13). A p p a r e n t digestibility of ADIN decreased linearly ( P < . 0 0 5 ) w i t h heating (Table 2). This relationship was n o t observed for heated haylages (13). Total digestible nutrients c o n t e n t was unaffected (P>.05) by heating (Table 2). Nitrogen utilization data are in Table 3. Although N excreted in urine decreased linearly (P<.025) with heating, the N retained was unaffected (P>.05). The negative r between heating and urinary N excretion suggested the reduction of forage protein solubility in the r u m e n although in vitro measurements did n o t support this suggestion (Table 1). Regression slopes in Table 3 suggested that forage protein digestion was reduced in the r u m e n b u t was increased in the small intestine. For heated haylage, forage protein digestion was reduced both in the r u m e n and in the small intestine (13). The lack of significant i m p r o v e m e n t in N r e t e n t i o n could be due to inadequate reduction in protein solubility, insufficient intake of digestible energy, marginal c o n t e n t of sulphurcontaining a m i n o acids (SAA) in forage protein Journal of Dairy Science Vol. 60, No. 9, 1977
for wool growth (2), and the physiological status of the sheep. Nitrogen r e t e n t i o n was 10.5 g per day for sheep receiving 22.9 g N infusion through ileum (83% total N intake) compared to - 2 . 0 g N per day for sheep receiving no infusion (3). Since the total daily N intake, fecal N excretion, and the size of sheep used in (3) were comparable to ours, dry heating at 90 C was apparently n o t effective in improving N utilization of alfalfa hay for sheep. ACKNOWLEDGMENT
Financial assistance from the Ontario Ministry of Agriculture and Food, and 13. H. Bull Memorial F u n d is acknowledged gratefully. REFERENCES
1 Association of Official Agricultural Chemists. 1970. Official methods of analysis, l l t h ed. Washington, DC. 2 Barry, T. N. 1976. The effectiveness of formaldehyde treatment in protecting dietary protein from rumen microbial degradation. Proc. Nutr. Soc. 35:221. 3 Ben-Ghedalia, D., H. Tagari, and A. Bondi. 1976. The ileum of the sheep as a site of protein digestion. Br. J. Nutr. 36:211. 4 Glimp, H. A., M. R. Karr, C. O. Little, P. G. Woolfolk, G. F. Mitchell, Jr., and L. W. Hudson. 1967. Effect of reducing soybean protein solubility by dry heat on the protein utilization of young lambs. J. Anim. Sci. 26:858. 5 Goering, H. K., and P. J. Van Soest. 1970. Forage
TECHNICAL NOTE
6
7
8 9
fiber analyses (apparatus, reagents, procedures, and some applications). Agr. Handbook 379, USDA. Marsh, R., and J. C. Murdoch. 1975. Effect of some-crop-drying processes on the digestibility and voluntary intake of herbage by sheep. J. Brit. Grassld. Soc. 30:9. Mellenberger, R. W., L. D. Satter, M. A. Millett, and A. J. Baker. 1970. An in vitro technique for estimating digestibility of treated and untreated wood. J. Anita. Sci. 30:1005. Miller, L. G., D. C. Clanton, L. F. Nelson, and O. E. Hoehne. 1967. Nutritive value of hay baled at various moisture contents. J. Anita. Sci. 26:1369. Tagari, H., I. Ascarelli, and A. Bondi. 1962. The influence of heating on the nutritive value of
1439
soya-bean meal for ruminants. Br. J. Nutr. 16:237. 10 Van Soest, P. J. 1965. Use of detergents in analysis of fibrous feeds. III. Study of effects of heating and drying on yield of fiber and lignin in forages. J. Ass. Off. Agr. Chem. 48:785. 11 Yu, Y. 1976. Relationship between measurements of heating and acid-detergent insoluble nitrogen in heat damaged fresh alfalfa, haylage, and hay. J. Dairy Sci. 59:1845. 12 Yu, Y., and J. W. Thomas. 1976. Estimation of the extent of heat damage in alfalfa haylage by laboratory measurement. J. Anita. Sci. 42: 766. 13 Yu, Y., and D. M. Veira. 1977. Effect of artificial heating of alfalfa haylage on chemical composition and sheep performance. J. Anim. Sci. 44:1112.
Journal of Dairy Science Vol. 60, No. 9, 1977
Alfalfa-bromegrass hay was heated at 90 C for 0, 8, 16, 24, 32, 40, 48, or 56 h. Heating had no clear effect on chemical composition, in vitro rumen digestion, voluntary intake, digestion of major nutrients, and nitrogen retention in sheep. Digestibility of acid-detergent insoluble nitrogen was reduced linearly with heating. Nitrogen utilization of heated hay was not improved significantly by reduced nitrogen excretion in urine and increased nitrogen retention. INTRODUCTION
Proper amount of heating of soybean meal reduced protein solubility, rumen ammonia production, and improved nitrogen (N) utilization (4, 9). However, heating of high-moisture feed such as alfalfa haylage (47% dry matter) in sealed condition increased acid-detergent insoluble N (ADIN) content, reduced N digestibility, and N retention (13). Whether nitrogen utilization of alfalfa hay can be improved by heating has not been evaluated. The objective of our trial was to evaluate the effect of heating of alfalfa-bromegrass hay on chemical composition, voluntary intake, digestion, and N utilization in sheep. MATERIALS AND METHODS
Second growth alfalfa (Medicago sativa) and bromegrass (Bromus inermis) hay (sun-cured) about 3 cm in length was heated at 90 C for O, 8, 16, 24, 32, 40, 48, or 56 h in a forced-draft oven 1. Equivalent heating units (degree-hours above 35 C) ranged from 0 to 3080. Each hay was mixed and sampled (n=4) for determination of dry matter (DM), proximate analysis constituents (1), neutral-detergent fiber (NDF),
Received March 15, 1977. Model 1207, Hotpack Ltd., Waterloo, Ontario. 1977 J Dairy Sci 60:1436-1439
acid-detergent fiber (ADF), ADIN, acid-pepsin insoluble N (APIN) (5), and in vitro digestion of DM and N (7). Six hays, excluding those heated for 32 and 48 h, were fed to 12 sheep averaging about 42 kg (6 mo old) for two periods (21 days/period). Sheep were reassigned randomly to treatments for the second period. Feces and urine were collected during the last 7 days of each period. Feeding was restricted to 90% of the voluntary intake determined during the first 14 days of each period. Feces were freeze-dried and analyzed for the same variables as for hay. Urine was analyzed for total N (1). Compositional and sheep performance data were analyzed by a stepwise deletion (P = .05) polynomial regression program.
RESULTS A N D DISCUSSION
Heating had no effect (P>.05) on proximate analysis constituents and NDF (Table 1). Similar were (6, 8, 13). Acid-detergent fiber and ADIN decreased linearly (P<.05) with heating while the opposite was apparent for hemicellulose and APIN (Table 1). These trends do not agree with with result of Yu (11) who heated alfalfa hay at 88 C for 0 to 48 h. The ADIN%N content in unheated hay was high relative to 7% for normal forages (10). Thus, some heat damage might have occurred during the haymaking process, and the artificial dry heating produced no further damage. In vitro rumen DM digestion was unaffected (P>.05) by heating, but N digestion increased linearly (P<.01) with heating (Table 1). The positive bl with DM and N digestion suggested that heating produced neither heat damage nor protection for forage protein from rumen microbial degradation. Voluntary intake, digestibility of DM, N, ADF, crude fiber, and N-free-extract were unaffected (P>.05) by heating although b l ' s generally were negative (Table 2). These in vivo data confirmed trends from compositional anal-
1436
TECHNICAL NOTE
143 7
TABLE 1. Effect of dry heating (90 C, 0 to 56 h) on c o m p o s i t i o n and in vitro digestion of alfalfa-grass hay evalu a t e d by regression analysis a.
Item
Unheated hay
Regression with degree-hours>35 C Sig. b b ac r2
Dry matter (DM, %)
93
Chemical composition (% DM) Total nitrogen (N) Crude fiber N free extract Ether extract Neutral-detergent fiber Acid-detergent fiber Hemicellulose Acid-detergent insoluble N (ADIN) ADIN (% N) Acid-pepsin insoluble N (% N)
2.7 36 39 1.3 57 46 11 .335 12.8 26
NS d NS NS NS NS <.05 <.005 <.005 <.01 <.01
.33 -3.74 -1.19 .50 -.23 -13.44 13.20 -.19 -8.81 4.76
In vitro m m e n digestion (%) Dry m a t t e r Nitrogen
39 36
NS < .01
10.45 4.76
.02 .01 .003 .02 .0001 .15 .40 .34 .23 .09
.11 .21
a N = 32. bsig. = significance. Quadratic response was no t significant (P>.05) for all variables. C
Regresmon slope (× 10 -4).
d N S = n o t significant (P>.05).
T A B L E 2. Effect of dry heating (90 C, 0 to 56 h) of alfalfa-grass hay on sheep performance evaluated by regression analysis a. Unheated Item Voluntary intake Actual (kg DMd/day) % Body weight
hay
1.159 2.57
Regression with degree-hours>35 C Sig. b
NS e NS
Apparent digestibility (%) Dry matter Nitrogen (N) Acid-detergent fiber Crude fiber N free extract Ether extract Acid-detergent insoluble N
59.8 68.7 54.7 55.7 64.9 43.0 39.1
NS NS NS NS NS <.025 <.005
Total digestible nutrients (%)
57.6
NS
b ac
-.03 -.02
-2.10 -8.09 -2.84 -6.44 .09 29.93 -25.61 -.97
r2
.001 0
.02 .06 .01 .05 0 .21 .60 .004
aN = 24. bsig. = significance. Quadratic response was n o t significant (P>.05) for all variables. CRegression slope (× 10-"). dDM = dry matter. eNS = n o t significant (P>.05). Journal of Dairy Science Vol. 60, No. 9, 1977
1438
",'U ET AL.
TABLE 3. Effect of dry heating (90 C, 0 to 56 h) of alfalfa-grass hay on nitrogen utilization in sheep evaluated by regression analysisa.
Item
Unheated hay
Regression with degree-hours>35 C Sig.b bl c r2
Nitrogen (N, g/day) Intake Feces Urine Retention
27.5 8.6 19.7 .7
NS d NS <.025 NS
1.50 5.73 -9.99 8.56
.002 .05 .24 .14
NS
42.77
.14
N retention (% N digested)
3.7
a N = 24. bsig. = significance. Quadratic response was not significant (P>.05) for all variables. CRegression slope (X 10-4).
dNS = not significant (P>.05).
ysis and in vitro digestion that hays were n o t damaged by heating, b u t the general relationship between digestibility and laboratory measurements was different from that of heated haylages (12, 13). Ether extract digestibility increased linearly (P<.025) with heating (Table 2) and was in accordance with (13). A p p a r e n t digestibility of ADIN decreased linearly ( P < . 0 0 5 ) w i t h heating (Table 2). This relationship was n o t observed for heated haylages (13). Total digestible nutrients c o n t e n t was unaffected (P>.05) by heating (Table 2). Nitrogen utilization data are in Table 3. Although N excreted in urine decreased linearly (P<.025) with heating, the N retained was unaffected (P>.05). The negative r between heating and urinary N excretion suggested the reduction of forage protein solubility in the r u m e n although in vitro measurements did n o t support this suggestion (Table 1). Regression slopes in Table 3 suggested that forage protein digestion was reduced in the r u m e n b u t was increased in the small intestine. For heated haylage, forage protein digestion was reduced both in the r u m e n and in the small intestine (13). The lack of significant i m p r o v e m e n t in N r e t e n t i o n could be due to inadequate reduction in protein solubility, insufficient intake of digestible energy, marginal c o n t e n t of sulphurcontaining a m i n o acids (SAA) in forage protein Journal of Dairy Science Vol. 60, No. 9, 1977
for wool growth (2), and the physiological status of the sheep. Nitrogen r e t e n t i o n was 10.5 g per day for sheep receiving 22.9 g N infusion through ileum (83% total N intake) compared to - 2 . 0 g N per day for sheep receiving no infusion (3). Since the total daily N intake, fecal N excretion, and the size of sheep used in (3) were comparable to ours, dry heating at 90 C was apparently n o t effective in improving N utilization of alfalfa hay for sheep. ACKNOWLEDGMENT
Financial assistance from the Ontario Ministry of Agriculture and Food, and 13. H. Bull Memorial F u n d is acknowledged gratefully. REFERENCES
1 Association of Official Agricultural Chemists. 1970. Official methods of analysis, l l t h ed. Washington, DC. 2 Barry, T. N. 1976. The effectiveness of formaldehyde treatment in protecting dietary protein from rumen microbial degradation. Proc. Nutr. Soc. 35:221. 3 Ben-Ghedalia, D., H. Tagari, and A. Bondi. 1976. The ileum of the sheep as a site of protein digestion. Br. J. Nutr. 36:211. 4 Glimp, H. A., M. R. Karr, C. O. Little, P. G. Woolfolk, G. F. Mitchell, Jr., and L. W. Hudson. 1967. Effect of reducing soybean protein solubility by dry heat on the protein utilization of young lambs. J. Anim. Sci. 26:858. 5 Goering, H. K., and P. J. Van Soest. 1970. Forage
TECHNICAL NOTE
6
7
8 9
fiber analyses (apparatus, reagents, procedures, and some applications). Agr. Handbook 379, USDA. Marsh, R., and J. C. Murdoch. 1975. Effect of some-crop-drying processes on the digestibility and voluntary intake of herbage by sheep. J. Brit. Grassld. Soc. 30:9. Mellenberger, R. W., L. D. Satter, M. A. Millett, and A. J. Baker. 1970. An in vitro technique for estimating digestibility of treated and untreated wood. J. Anita. Sci. 30:1005. Miller, L. G., D. C. Clanton, L. F. Nelson, and O. E. Hoehne. 1967. Nutritive value of hay baled at various moisture contents. J. Anita. Sci. 26:1369. Tagari, H., I. Ascarelli, and A. Bondi. 1962. The influence of heating on the nutritive value of
1439
soya-bean meal for ruminants. Br. J. Nutr. 16:237. 10 Van Soest, P. J. 1965. Use of detergents in analysis of fibrous feeds. III. Study of effects of heating and drying on yield of fiber and lignin in forages. J. Ass. Off. Agr. Chem. 48:785. 11 Yu, Y. 1976. Relationship between measurements of heating and acid-detergent insoluble nitrogen in heat damaged fresh alfalfa, haylage, and hay. J. Dairy Sci. 59:1845. 12 Yu, Y., and J. W. Thomas. 1976. Estimation of the extent of heat damage in alfalfa haylage by laboratory measurement. J. Anita. Sci. 42: 766. 13 Yu, Y., and D. M. Veira. 1977. Effect of artificial heating of alfalfa haylage on chemical composition and sheep performance. J. Anim. Sci. 44:1112.
Journal of Dairy Science Vol. 60, No. 9, 1977