Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol82.Issue3-4.Dec1999:
Animal Feed Science and Technology
82 (1999) 213±226
Wool growth in Merino wethers fed lupins untreated or
treated with heat or formaldehyde, with and without a
supplementation of rumen protected methionine
M. Rodehutscord*, P. Young, N. Phillips, C.L. White
CSIRO Division of Animal Production, Private Bag, PO Wembley, Western Australia 6014, Australia
Received 2 June 1999; received in revised form 9 August 1999; accepted 28 August 1999
Abstract
Lupins were treated by either heat (1158C for 1 h) or by formaldehyde (0.4 g 100 gÿ1 crude
protein). The fractional rate of disappearance of N from dacron bags suspended in the rumen of
steers was reduced by either treatment. Assuming a rumen outflow rate of 0.03 hÿ1, effective rumen
degradability was 0.96, 0.94 and 0.92 for protein and 0.84, 0.82 and 0.81 for dry matter in
untreated, heat- and formaldehyde-treated lupins. Concentration of acid detergent insoluble
nitrogen in lupins was not enhanced by treatment.
A 3 2 factorial experiment was performed with Merino wethers to study the effect of treating
lupins on wool growth and body weight gain on a feeding level slightly above maintenance. Factors
were lupin treatment (untreated, heat- and formaldehyde-treated) and supplementation of a rumen
protected methionine (3 g methionine per day, yes or no). The diet contained (kgÿ1) 620 g chaffed
oaten hay, 350 g broken lupins and 30 g mineral premix and was supplied once daily to sheep at a
level of 900 g per day air dry or approximately 8 MJ per day ME. Seventy-two sheep were fed the
diet containing untreated lupins without methionine supplementation during a 4 week pretreatment
period and were subsequently allocated to one out of the six treatments according to pretreatment
wool growth rate (n 12 sheep per treatment). Treatment lasted for 8 weeks. Comparative clean
wool growth rate was determined on mid-side patches of approximately 100 cm2 shorn in 4 weekintervals. Faeces and urine were collected for 7 days at the end of the experiment with six sheep per
treatment. Both body weight gain and clean wool growth were not significantly effected by either
treatment of lupins. Supplementation of rumen protected methionine significantly increased both
body weight gain (by 27%) and clean wool growth. The effect of supplementary rumen protected
methionine on clean wool growth was twice as high in sheep fed either heat- or formaldehyde*
Corresponding author. Present address: Institut fuÈr ErnaÈhrungswissenschaften, UniversitaÈt Halle-Wittenberg,
06099 Halle, Germany. Tel.: 49-345-5522701; fax: 49-345-5527124
E-mail address: rodehutscord@mluters1.landw.uni-halle.de (M. Rodehutscord)
0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 1 0 8 - X
214
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
treated lupins (37 and 36%, respectively) as compared to sheep fed untreated lupins (19%). Sulphur,
but not nitrogen concentration in clean wool was significantly increased by supplementation of
rumen protected methionine. The efficiency of utilisation of metabolisable protein (defined
according to [AFRC, 1993. Energy and protein requirements of ruminants. CAB International,
Wallingford]) for N retention was improved by 13, 22 and 27% for diets containing untreated, heatand formaldehyde-treated lupins due to supplementary rumen protected methionine. Organic matter
digestibility and daily faecal N excretion were unaffected by lupin treatment and by
supplementation of rumen protected methionine, indicating an equal ME supply to all sheep.
Correspondingly, the ratio of total purine derivatives to creatinine in urine was not significantly
affected by either experimental factor. 79% of total N in urine was present as urea.
It is concluded, that treating lupins with formaldehyde or heat cannot be recommended as a
means to improve the lupin protein quality for wool production unless extra rumen protected
methionine is supplemented. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Wool growth; Sheep; Lupins; Protein; Protection; Protected methionine
1. Introduction
During the dry summer and autumn periods in the West-Australian Mediterranean
climate zone pasture growth completely stops and wool growth of sheep as well as wool
quality are reduced, combined with a loss in body weight (BW) of sheep. Supplementary
grain feeding is commonly practised during this period with the Australian sweet lupin
seed (Lupinus angustifolius) as a grain preferred by farmers. It is available on many WestAustralian farms because it forms part of the rotation. Lupins are easy to handle and to
feed (spread on the ground) and they are high in metabolisable energy (ME)
concentration.
Wool growth is a function mainly of the amount of amino acids reaching the intestine
(Hynd and Allden, 1985) rather than energy supply (Black et al., 1973; Reis et al., 1992).
Furthermore, the amino acid pattern of the protein which reaches the intestine may effect
wool growth since sulphur-containing amino acids (SAA) are first limiting in terms of
wool protein synthesis (Reis and Tunks, 1978). Therefore, the ruminally degradable
proportion of dietary protein becomes a critical factor for wool growth and, on
isonitrogenous diets, wool growth responds well to less degradable proteins, particularly
when they are high in SAA concentration (Coombe, 1992; Masters and Mata, 1996;
White et al., 1999). Consequently, SAA supplementation in the form of methionine,
cysteine or cystine is effective for enhancing wool growth if degradation in the rumen is
avoided (Reis and Tunks, 1978).
Lupins contain approximately 32±35% crude protein (Petterson et al., 1997), which
makes them appear to be an effective protein supplement for sheep. But lupin protein is
highly degradable in the rumen (Antoniewicz et al., 1992; AFRC, 1993; White et al.,
1999) and contains only, on an average, 2.2 g methionine cystine 100 gÿ1 CP
(Degussa, 1996). This, in fact, makes lupins a low quality protein supplement in terms of
wool growth, and a better wool growth response than with lupins could be detected with
less degradable proteins higher in SAA concentration such as canola meal (Masters and
Mata, 1996). Surprisingly, even supplementary oats prove equal to or better than lupins in
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
215
promoting wool growth (White et al., 1999). As there obviously are some advantages
from using lupins as a supplement, we were aiming at trying to improve the value of lupin
protein for wool production.
Both formaldehyde treatment (Crooker et al., 1986; Antoniewicz et al., 1992) and heat
treatment (Satter, 1986) were shown to be effective means to reduce the ruminal
degradation of protein in-vitro. Toasted broken lupins (3 min at 1328C) showed
remarkably lower in situ protein degradability as compared to untreated lupins without
any difference in intestinal digestibility of rumen undegraded protein (Goelema et al.,
1998). Wool growth in sheep fed a lupin based diet responded well to an increase in
methionine supply by either genetic enhancement of methionine concentration in lupin
protein (White et al., 1998) or by supplementation of free methionine protected against
degradation in the rumen (Mata et al., 1995; White et al., 1999). It was the aim of the
present study to investigate how sheep fed near maintenance on a lupin based diet
respond, in wool growth and body weight gain (BWG), to treated lupin protein and to
rumen protected methionine. A 3 2 factorial experiment was conducted with the factors
`lupin treatment' (untreated, heat- or formaldehyde-treated) and `methionine supplementation' (yes or no).
2. Materials and methods
2.1. Lupin treatment
Lupins (L. angustifolius, mixed varieties) were taken from one batch. For heat
treatment, whole seed lupins were put in layers of approximately 2 cm high in drawers
with a perforated stainless steel bottom. Drawers were put into a large-size conventional
oven dryer and lupins remained inside for 1 h after air temperature had reached its
maximum of 1158C. Lupins were then removed from the oven and spread in a thin layer
on the floor in order to cool down immediately. For formaldehyde treatment, lupins were
gristed (course ground) and mixed with formaldehyde (0.4 g 100 gÿ1 CP; Hamilton et al.,
1992). This level was chosen in order to avoid a reduction in intestinal digestibility of
ruminally undegradable protein which potentially could result from a too high
formaldehyde level.
Untreated and heat treated lupins were cracked in a hammer mill (1 cm hole diameter
in the sieve) before being mixed into the diets. Analysed concentrations of dry matter and
crude protein are shown in Table 1 for the three different lupin batches. Amino acid
composition was determined for the untreated lupins only.
2.2. Diets
Diets consisted of chaffed oaten hay, lupins and a mineral premix (Siromin1) (Table 2)
and were calculated to contain approximately 8 MJ ME kgÿ1 DM. Components were
mixed in batches of 500 kg in advance for the entire experiment and stored in bags at
room temperature until feeding. Diets for half of the animals were supplied with 10 g per
day Lactet1 (Nippon Soda), a product containing 30% DL-methionine, which can be
216
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
Table 1
Analytical data for lupins (results expressed on an air dry basis)
Lupins
Untreated
Heat-treated
Formaldehyde-treated
Dry matter (g kg )
Crude protein (g kgÿ1)
ADINa (g kgÿ1)
906
302
0.45
943
304
0.45
911
283
0.36
Amino acids (g/16 g N)
Alanine
Arginine
Aspartic acid
Cystine
Glutamic acid
Glycine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Proline
Serine
Threonine
Tryptophan
Valine
3.5
10.1
9.8
1.45
19.0
4.2
2.6
4.0
6.6
4.6
0.6
4.0
4.0
4.8
3.4
0.8
3.9
ÿ1
a
ADIN: acid detergent insoluble nitrogen.
Table 2
Diets
Lupins
Diet
Untreated
Heat-treated
Formaldehyde-treated
Composition (g kgÿ1)
Oaten hay
Lupins, untreated
Lupins, heat-treated
Lupins, formaldehyde-treated
Mineral mixa
620
350
±
±
30
620
±
350
±
30
620
±
±
350
30
Analysed
Dry matter (g kgÿ1)
Crude protein (g kgÿ1 DM)
Sulphur (g kgÿ1 DM)
921
132
3.1
927
136
3.6
923
120
2.7
a
Siromin1 contained (g kgÿ1 mineral mix): Na 176, K 116, Ca 48, S 39, P 15, Mg 4, Fe 1.94, Zn 1.16, Mn
0.58, Cu 0.116, Mo 0.04, Co 0.08, Se 0.006, I 0.004, Ni 0.004, Cr 0.004, V 0.004, B 0.004.
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
217
assumed effectively protected against degradation in the rumen of sheep fed at
maintenance level (Muramatsu et al., 1994; Mata et al., 1995). Lactet was not mixed into
the diet but separately preweighed in small plastic vessels on a daily basis and spread over
the feed immediately after this had been put into the troughs. Amount of Lactet was
calculated to supply approximately twice the amount of absorbable SAA supplied with
the untreated lupin diet.
2.3. Animals, feeding and sampling
Seventy-two Merino wether sheep weighing, on an average, 34 kg were selected from
the Yalanbee research station flock and brought into the animal house where they were
penned individually on wooden slatted floors. Sheep were approximately 5 months old
and had been weaned at 3 months of age. They were given an adjustment period of 3
weeks during which the amount of feed was increased from 600 to 900 g per day (air
dry). This quantity was calculated to allow for a ME supply slightly above maintenance
and it was kept constant throughout the entire experiment. A 4 week pretreatment period
followed for wool growth measurement under standardised feeding conditions. During
adjustment and pretreatment all sheep were fed the diet containing untreated lupins
without Lactet. Twelve sheep were allocated to one out of the six dietary treatments
stratified according to BWG and wool growth during the pretreatment period. Dietary
treatments lasted for 8 weeks. Diets (900 g per day air dry) were given in one meal in the
morning. No feed refusals were recorded. Drinking water was continuously available
from nipple drinkers.
Body weight was recorded at weekly intervals. A mid-side patch of approximately
100 cm2 was shorn with small animal clippers (ANDIS with a model AG No. 40 cutting
head) and a dyeband was applied to wool alongside the patch at the beginning of the
pretreatment period (Langlands and Wheeler, 1968). Sheep were shorn on these patches
and dyebands were applied every 4 weeks (end of pretreatment, after 4 and 8 weeks on
treatment). During the last 7 days on treatment, faeces were quantitatively collected from
six sheep out of each treatment. Sheep were fitted with harnesses and faeces were
collected in plastic bags as described by Cole et al. (1996). Pizzle harnesses were attached
and urine was collected in bottles underneath the floor. Bottles contained 100 ml diluted
sulphuric acid (10% v/v) to keep pH in bulked urine samples below 2. As leakage of the
urine collection unit could not be completely avoided for all animals, urinary excretion
cannot be regarded as quantitatively determined. Concentration of different urinary N
fractions will, therefore, be expressed in relation to urinary creatinine concentration.
However, collection of urine was complete for most of the animals and we estimate that
the spot sample comprised at least 80% of total urine from 7 days for all animals.
2.4. Degradability study
In situ degradability was determined for untreated and treated lupins in four rumencannulated steers (600 kg BW) fed on a maintenance diet which consisted of 50%
cereal hay, 24% lupins, 24% faba beans and 2% mineral mix (Siromin1). Lupin samples
were ground in a mill with a 3 mm sieve and weighed into dacron bags with a 50 mm pore
218
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
size. Lines with the bags were washed for one wash and spin cycle in an automatic
washing machine (16 min) and then suspended in the rumen of the steers for 48 h at a
maximum. One set of bags was dried and weighed after removal from the washing
machine to give the zero time solubility, and the remainder were removed from the rumen
at intervals of 2, 4, 8, 12, 16, 24 and 48 h (one bag per steer per lupin batch per time).
Bags with the residual material were immediately placed in cold water, and then washed
for one cycle in the automatic washing machine, dried at 558C for 24 h and analysed for
nitrogen. The exponential function y a b(1 ÿ eÿct) was fitted to the data, where y is
the cumulative disappearance of nitrogen from the bags depending on t, t the incubation
time (hours), a the soluble fraction (determined as time zero washout), b the potentially
degradable fraction and c the fractional rate of degradation of feed nitrogen per hour
(AFRC, 1993).
2.5. Analysis
Greasy wool samples were washed for 6 min in hot water (658C) and Scour (1 ml/l
water) (Dolmar Australia), a commercially available heavy duty wool scouring
compound and dried in a humidified room for 72 h before weighing. Results for clean
wool growth (CWG) are expressed on a 88% dry matter basis (humidified clean wool).
Clean wool growth during treatment is covariance adjusted for individuals based on
respective pretreatment values. Feed and faeces were dried at 708C and ground. Ash was
determined after ignition in a muffle furnace at 5508C. Feed, faeces and urine were
analysed for Kjeldahl-N (Tecator-system) and crude protein was calculated as N 6.25.
Urea-N was analysed on a Cobas Mira clinical chemistry analyser (Roche1) using a
commercially available kit (Sigma Diagnostics1). Purine derivatives in urine were
determined according to Chen and Gomes (1992). Wool nitrogen and sulphur were
determined on a Leco1 NS2000 nitrogen and sulphur analyser using total combustion
method. Statistical analysis and parameter estimate were performed on a personal
computer using the software package SPSS 7.5 for Windows.
3. Results
Supplementation of rumen protected methionine from Lactet significantly increased
BWG of sheep by approximately 15 g per day or 27% without a significant interaction
with the lupin treatment (Table 3). Body weight gain of sheep receiving either of the
treated lupins was numerically lower than in sheep fed the untreated lupins but this effect
was statistically not significant. Clean wool growth during pretreatment averaged
0.87 0.02 mg cmÿ2 per day (mean SEM). In both 4 week treatment periods,
supplementation of rumen protected methionine significantly improved CWG by, on
average, 0.12 and 0.26 mg cmÿ2 per day in weeks 1±4 and weeks 5±8, respectively (Table
3). This effect of rumen protected methionine was higher when treated lupins rather than
untreated lupins were fed, particularly in weeks 5±8, when the interaction reached
significance level (P 0.058). To confirm that this interaction was statistically valid, the
wool data for weeks 5±8 lupin treatments were partitioned into two contrasts of 1 d.f.
219
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
Table 3
Body weight gain (BWG) and clean wool growth (CWG) in sheep fed differently treated lupins without or with a
rumen protected methionine (Lactet). Values for BWG and CWG are covariance-adjusted LS means (n 12
sheep per treatment)
Lupin
treatment
Lactet
None
BWG (g per day)
CWG (mg cm
Weeks 1±4
Weeks 5±8
ÿ2
Heat
Formaldehyde
Pooled P-value (ANOVA)
ÿ
ÿ
ÿ
SE
Treatment Lactet
60
73
56
71
51
69
2.3
0.353
82 (1999) 213±226
Wool growth in Merino wethers fed lupins untreated or
treated with heat or formaldehyde, with and without a
supplementation of rumen protected methionine
M. Rodehutscord*, P. Young, N. Phillips, C.L. White
CSIRO Division of Animal Production, Private Bag, PO Wembley, Western Australia 6014, Australia
Received 2 June 1999; received in revised form 9 August 1999; accepted 28 August 1999
Abstract
Lupins were treated by either heat (1158C for 1 h) or by formaldehyde (0.4 g 100 gÿ1 crude
protein). The fractional rate of disappearance of N from dacron bags suspended in the rumen of
steers was reduced by either treatment. Assuming a rumen outflow rate of 0.03 hÿ1, effective rumen
degradability was 0.96, 0.94 and 0.92 for protein and 0.84, 0.82 and 0.81 for dry matter in
untreated, heat- and formaldehyde-treated lupins. Concentration of acid detergent insoluble
nitrogen in lupins was not enhanced by treatment.
A 3 2 factorial experiment was performed with Merino wethers to study the effect of treating
lupins on wool growth and body weight gain on a feeding level slightly above maintenance. Factors
were lupin treatment (untreated, heat- and formaldehyde-treated) and supplementation of a rumen
protected methionine (3 g methionine per day, yes or no). The diet contained (kgÿ1) 620 g chaffed
oaten hay, 350 g broken lupins and 30 g mineral premix and was supplied once daily to sheep at a
level of 900 g per day air dry or approximately 8 MJ per day ME. Seventy-two sheep were fed the
diet containing untreated lupins without methionine supplementation during a 4 week pretreatment
period and were subsequently allocated to one out of the six treatments according to pretreatment
wool growth rate (n 12 sheep per treatment). Treatment lasted for 8 weeks. Comparative clean
wool growth rate was determined on mid-side patches of approximately 100 cm2 shorn in 4 weekintervals. Faeces and urine were collected for 7 days at the end of the experiment with six sheep per
treatment. Both body weight gain and clean wool growth were not significantly effected by either
treatment of lupins. Supplementation of rumen protected methionine significantly increased both
body weight gain (by 27%) and clean wool growth. The effect of supplementary rumen protected
methionine on clean wool growth was twice as high in sheep fed either heat- or formaldehyde*
Corresponding author. Present address: Institut fuÈr ErnaÈhrungswissenschaften, UniversitaÈt Halle-Wittenberg,
06099 Halle, Germany. Tel.: 49-345-5522701; fax: 49-345-5527124
E-mail address: rodehutscord@mluters1.landw.uni-halle.de (M. Rodehutscord)
0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 1 0 8 - X
214
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
treated lupins (37 and 36%, respectively) as compared to sheep fed untreated lupins (19%). Sulphur,
but not nitrogen concentration in clean wool was significantly increased by supplementation of
rumen protected methionine. The efficiency of utilisation of metabolisable protein (defined
according to [AFRC, 1993. Energy and protein requirements of ruminants. CAB International,
Wallingford]) for N retention was improved by 13, 22 and 27% for diets containing untreated, heatand formaldehyde-treated lupins due to supplementary rumen protected methionine. Organic matter
digestibility and daily faecal N excretion were unaffected by lupin treatment and by
supplementation of rumen protected methionine, indicating an equal ME supply to all sheep.
Correspondingly, the ratio of total purine derivatives to creatinine in urine was not significantly
affected by either experimental factor. 79% of total N in urine was present as urea.
It is concluded, that treating lupins with formaldehyde or heat cannot be recommended as a
means to improve the lupin protein quality for wool production unless extra rumen protected
methionine is supplemented. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Wool growth; Sheep; Lupins; Protein; Protection; Protected methionine
1. Introduction
During the dry summer and autumn periods in the West-Australian Mediterranean
climate zone pasture growth completely stops and wool growth of sheep as well as wool
quality are reduced, combined with a loss in body weight (BW) of sheep. Supplementary
grain feeding is commonly practised during this period with the Australian sweet lupin
seed (Lupinus angustifolius) as a grain preferred by farmers. It is available on many WestAustralian farms because it forms part of the rotation. Lupins are easy to handle and to
feed (spread on the ground) and they are high in metabolisable energy (ME)
concentration.
Wool growth is a function mainly of the amount of amino acids reaching the intestine
(Hynd and Allden, 1985) rather than energy supply (Black et al., 1973; Reis et al., 1992).
Furthermore, the amino acid pattern of the protein which reaches the intestine may effect
wool growth since sulphur-containing amino acids (SAA) are first limiting in terms of
wool protein synthesis (Reis and Tunks, 1978). Therefore, the ruminally degradable
proportion of dietary protein becomes a critical factor for wool growth and, on
isonitrogenous diets, wool growth responds well to less degradable proteins, particularly
when they are high in SAA concentration (Coombe, 1992; Masters and Mata, 1996;
White et al., 1999). Consequently, SAA supplementation in the form of methionine,
cysteine or cystine is effective for enhancing wool growth if degradation in the rumen is
avoided (Reis and Tunks, 1978).
Lupins contain approximately 32±35% crude protein (Petterson et al., 1997), which
makes them appear to be an effective protein supplement for sheep. But lupin protein is
highly degradable in the rumen (Antoniewicz et al., 1992; AFRC, 1993; White et al.,
1999) and contains only, on an average, 2.2 g methionine cystine 100 gÿ1 CP
(Degussa, 1996). This, in fact, makes lupins a low quality protein supplement in terms of
wool growth, and a better wool growth response than with lupins could be detected with
less degradable proteins higher in SAA concentration such as canola meal (Masters and
Mata, 1996). Surprisingly, even supplementary oats prove equal to or better than lupins in
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
215
promoting wool growth (White et al., 1999). As there obviously are some advantages
from using lupins as a supplement, we were aiming at trying to improve the value of lupin
protein for wool production.
Both formaldehyde treatment (Crooker et al., 1986; Antoniewicz et al., 1992) and heat
treatment (Satter, 1986) were shown to be effective means to reduce the ruminal
degradation of protein in-vitro. Toasted broken lupins (3 min at 1328C) showed
remarkably lower in situ protein degradability as compared to untreated lupins without
any difference in intestinal digestibility of rumen undegraded protein (Goelema et al.,
1998). Wool growth in sheep fed a lupin based diet responded well to an increase in
methionine supply by either genetic enhancement of methionine concentration in lupin
protein (White et al., 1998) or by supplementation of free methionine protected against
degradation in the rumen (Mata et al., 1995; White et al., 1999). It was the aim of the
present study to investigate how sheep fed near maintenance on a lupin based diet
respond, in wool growth and body weight gain (BWG), to treated lupin protein and to
rumen protected methionine. A 3 2 factorial experiment was conducted with the factors
`lupin treatment' (untreated, heat- or formaldehyde-treated) and `methionine supplementation' (yes or no).
2. Materials and methods
2.1. Lupin treatment
Lupins (L. angustifolius, mixed varieties) were taken from one batch. For heat
treatment, whole seed lupins were put in layers of approximately 2 cm high in drawers
with a perforated stainless steel bottom. Drawers were put into a large-size conventional
oven dryer and lupins remained inside for 1 h after air temperature had reached its
maximum of 1158C. Lupins were then removed from the oven and spread in a thin layer
on the floor in order to cool down immediately. For formaldehyde treatment, lupins were
gristed (course ground) and mixed with formaldehyde (0.4 g 100 gÿ1 CP; Hamilton et al.,
1992). This level was chosen in order to avoid a reduction in intestinal digestibility of
ruminally undegradable protein which potentially could result from a too high
formaldehyde level.
Untreated and heat treated lupins were cracked in a hammer mill (1 cm hole diameter
in the sieve) before being mixed into the diets. Analysed concentrations of dry matter and
crude protein are shown in Table 1 for the three different lupin batches. Amino acid
composition was determined for the untreated lupins only.
2.2. Diets
Diets consisted of chaffed oaten hay, lupins and a mineral premix (Siromin1) (Table 2)
and were calculated to contain approximately 8 MJ ME kgÿ1 DM. Components were
mixed in batches of 500 kg in advance for the entire experiment and stored in bags at
room temperature until feeding. Diets for half of the animals were supplied with 10 g per
day Lactet1 (Nippon Soda), a product containing 30% DL-methionine, which can be
216
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
Table 1
Analytical data for lupins (results expressed on an air dry basis)
Lupins
Untreated
Heat-treated
Formaldehyde-treated
Dry matter (g kg )
Crude protein (g kgÿ1)
ADINa (g kgÿ1)
906
302
0.45
943
304
0.45
911
283
0.36
Amino acids (g/16 g N)
Alanine
Arginine
Aspartic acid
Cystine
Glutamic acid
Glycine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Proline
Serine
Threonine
Tryptophan
Valine
3.5
10.1
9.8
1.45
19.0
4.2
2.6
4.0
6.6
4.6
0.6
4.0
4.0
4.8
3.4
0.8
3.9
ÿ1
a
ADIN: acid detergent insoluble nitrogen.
Table 2
Diets
Lupins
Diet
Untreated
Heat-treated
Formaldehyde-treated
Composition (g kgÿ1)
Oaten hay
Lupins, untreated
Lupins, heat-treated
Lupins, formaldehyde-treated
Mineral mixa
620
350
±
±
30
620
±
350
±
30
620
±
±
350
30
Analysed
Dry matter (g kgÿ1)
Crude protein (g kgÿ1 DM)
Sulphur (g kgÿ1 DM)
921
132
3.1
927
136
3.6
923
120
2.7
a
Siromin1 contained (g kgÿ1 mineral mix): Na 176, K 116, Ca 48, S 39, P 15, Mg 4, Fe 1.94, Zn 1.16, Mn
0.58, Cu 0.116, Mo 0.04, Co 0.08, Se 0.006, I 0.004, Ni 0.004, Cr 0.004, V 0.004, B 0.004.
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
217
assumed effectively protected against degradation in the rumen of sheep fed at
maintenance level (Muramatsu et al., 1994; Mata et al., 1995). Lactet was not mixed into
the diet but separately preweighed in small plastic vessels on a daily basis and spread over
the feed immediately after this had been put into the troughs. Amount of Lactet was
calculated to supply approximately twice the amount of absorbable SAA supplied with
the untreated lupin diet.
2.3. Animals, feeding and sampling
Seventy-two Merino wether sheep weighing, on an average, 34 kg were selected from
the Yalanbee research station flock and brought into the animal house where they were
penned individually on wooden slatted floors. Sheep were approximately 5 months old
and had been weaned at 3 months of age. They were given an adjustment period of 3
weeks during which the amount of feed was increased from 600 to 900 g per day (air
dry). This quantity was calculated to allow for a ME supply slightly above maintenance
and it was kept constant throughout the entire experiment. A 4 week pretreatment period
followed for wool growth measurement under standardised feeding conditions. During
adjustment and pretreatment all sheep were fed the diet containing untreated lupins
without Lactet. Twelve sheep were allocated to one out of the six dietary treatments
stratified according to BWG and wool growth during the pretreatment period. Dietary
treatments lasted for 8 weeks. Diets (900 g per day air dry) were given in one meal in the
morning. No feed refusals were recorded. Drinking water was continuously available
from nipple drinkers.
Body weight was recorded at weekly intervals. A mid-side patch of approximately
100 cm2 was shorn with small animal clippers (ANDIS with a model AG No. 40 cutting
head) and a dyeband was applied to wool alongside the patch at the beginning of the
pretreatment period (Langlands and Wheeler, 1968). Sheep were shorn on these patches
and dyebands were applied every 4 weeks (end of pretreatment, after 4 and 8 weeks on
treatment). During the last 7 days on treatment, faeces were quantitatively collected from
six sheep out of each treatment. Sheep were fitted with harnesses and faeces were
collected in plastic bags as described by Cole et al. (1996). Pizzle harnesses were attached
and urine was collected in bottles underneath the floor. Bottles contained 100 ml diluted
sulphuric acid (10% v/v) to keep pH in bulked urine samples below 2. As leakage of the
urine collection unit could not be completely avoided for all animals, urinary excretion
cannot be regarded as quantitatively determined. Concentration of different urinary N
fractions will, therefore, be expressed in relation to urinary creatinine concentration.
However, collection of urine was complete for most of the animals and we estimate that
the spot sample comprised at least 80% of total urine from 7 days for all animals.
2.4. Degradability study
In situ degradability was determined for untreated and treated lupins in four rumencannulated steers (600 kg BW) fed on a maintenance diet which consisted of 50%
cereal hay, 24% lupins, 24% faba beans and 2% mineral mix (Siromin1). Lupin samples
were ground in a mill with a 3 mm sieve and weighed into dacron bags with a 50 mm pore
218
M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
size. Lines with the bags were washed for one wash and spin cycle in an automatic
washing machine (16 min) and then suspended in the rumen of the steers for 48 h at a
maximum. One set of bags was dried and weighed after removal from the washing
machine to give the zero time solubility, and the remainder were removed from the rumen
at intervals of 2, 4, 8, 12, 16, 24 and 48 h (one bag per steer per lupin batch per time).
Bags with the residual material were immediately placed in cold water, and then washed
for one cycle in the automatic washing machine, dried at 558C for 24 h and analysed for
nitrogen. The exponential function y a b(1 ÿ eÿct) was fitted to the data, where y is
the cumulative disappearance of nitrogen from the bags depending on t, t the incubation
time (hours), a the soluble fraction (determined as time zero washout), b the potentially
degradable fraction and c the fractional rate of degradation of feed nitrogen per hour
(AFRC, 1993).
2.5. Analysis
Greasy wool samples were washed for 6 min in hot water (658C) and Scour (1 ml/l
water) (Dolmar Australia), a commercially available heavy duty wool scouring
compound and dried in a humidified room for 72 h before weighing. Results for clean
wool growth (CWG) are expressed on a 88% dry matter basis (humidified clean wool).
Clean wool growth during treatment is covariance adjusted for individuals based on
respective pretreatment values. Feed and faeces were dried at 708C and ground. Ash was
determined after ignition in a muffle furnace at 5508C. Feed, faeces and urine were
analysed for Kjeldahl-N (Tecator-system) and crude protein was calculated as N 6.25.
Urea-N was analysed on a Cobas Mira clinical chemistry analyser (Roche1) using a
commercially available kit (Sigma Diagnostics1). Purine derivatives in urine were
determined according to Chen and Gomes (1992). Wool nitrogen and sulphur were
determined on a Leco1 NS2000 nitrogen and sulphur analyser using total combustion
method. Statistical analysis and parameter estimate were performed on a personal
computer using the software package SPSS 7.5 for Windows.
3. Results
Supplementation of rumen protected methionine from Lactet significantly increased
BWG of sheep by approximately 15 g per day or 27% without a significant interaction
with the lupin treatment (Table 3). Body weight gain of sheep receiving either of the
treated lupins was numerically lower than in sheep fed the untreated lupins but this effect
was statistically not significant. Clean wool growth during pretreatment averaged
0.87 0.02 mg cmÿ2 per day (mean SEM). In both 4 week treatment periods,
supplementation of rumen protected methionine significantly improved CWG by, on
average, 0.12 and 0.26 mg cmÿ2 per day in weeks 1±4 and weeks 5±8, respectively (Table
3). This effect of rumen protected methionine was higher when treated lupins rather than
untreated lupins were fed, particularly in weeks 5±8, when the interaction reached
significance level (P 0.058). To confirm that this interaction was statistically valid, the
wool data for weeks 5±8 lupin treatments were partitioned into two contrasts of 1 d.f.
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M. Rodehutscord et al. / Animal Feed Science and Technology 82 (1999) 213±226
Table 3
Body weight gain (BWG) and clean wool growth (CWG) in sheep fed differently treated lupins without or with a
rumen protected methionine (Lactet). Values for BWG and CWG are covariance-adjusted LS means (n 12
sheep per treatment)
Lupin
treatment
Lactet
None
BWG (g per day)
CWG (mg cm
Weeks 1±4
Weeks 5±8
ÿ2
Heat
Formaldehyde
Pooled P-value (ANOVA)
ÿ
ÿ
ÿ
SE
Treatment Lactet
60
73
56
71
51
69
2.3
0.353