GB2263065A - Coated amino acids for increasing wool production and quality and liveweight of lambs - Google Patents

Abstract

Wool production, in terms of both quality and quantity, and also liveweight, are improved in lambs by administration of a coated amino acid, especially methionine or lysine. The coating may comprise a basic amino copolymer (especially copoly (styrene/vinylpyridene)) or zein and a hydrophobic substance of melting point greater than 60 DEG C (especially stearic acid), and/or a water-insoluble polymer (especially ethylcellulose).

Description

METHOD FOR INCREASING WOOL PRODUCTION AND OUALITY. AND LIVEWEIGHT OF LAMBS The invention relates to increasing wool production and quality and liveweight of lambs.

Reis and Schinckel, Australian Journal of Biological Sciences, 1963, disclosed that injection of either Lcysteine or DL-methionine into the abomasum at a dose of 1.5g to 3g per day increases the growth of wool in sheep.

The addition of sulphur-containing amino acids into the feed ration of ovines, on the other hand, has little effect on the growth of wool in sheep because bacterial metabolism of the sulphur amino acids occurs in the first stomach or rumen and so only a small proportion of the dose administered is available for absorption.

From a practical agricultural point of view it is impossible to envisage injecting amino acids into the abomasum in grazing livestock. For the livestock to benefit from the amino acids it is necessary to protect the amino acids from bacterial degradation so as to allow them to pass through the rumen without degradation while allowing them to be absorbed sufficiently rapidly in the abomasum and/or the intestines to exert a beneficial nutritional effect.

It has now been found that wool production in a lamb may be increased by administering an effective amount of a protected amino acid to a growing lamb. The increase in wool production is due to an increase in wool fibre length, an increase in wool fibre diameter, and/or an increase in the volume growth rate of the wool. In addition, the condition of the lamb, including especially its weight and its chances of survival, are significantly improved by the addition of the protected amino acid.

In one aspect, the invention provides a method for increasing the liveweight of a lamb at a given age, and therefore inter alia its market value and its chances of survival, which comprises feeding to a growing lamb a diet comprising an effective amount of a protected amino acid.

In another aspect, the invention provides a method for increasing the growth rate of wool in a lamb which comprises administering an effective amount of a protected amino acid to a growing lamb.

In another aspect, the invention provides a method for increasing the quality of wool produced by a lamb which comprises administering an effective amount of a protected amino acid to a growing lamb. More particularly, the fibre length, and volume growth rate, of wool produced by a lamb may be increased by administering an effective amount of a protected amino acid to a growing lamb. Also the fibre tensile strength of wool produced by a lamb may be increased by administering an effective amount of a protected amino acid to a growing lamb.

Preferably the growing lamb is a weaner lamb. A particularly preferred weaner lamb is a Nerino weaner lamb as the wool of such lambs is of a high value. The method of the invention is however applicable to the lambs of all breeds of sheep, including breeds (or cross-breeds) grown primarily for meat production.

The amino acid is usually an essential amino acid for lambs, preferably methionine or lysine or a mixture of both, and more preferably methionine.

The amino acid administered to the lamb may be protected in the following manner with, for example, one of the following polymer-containing coatings.

The first type of coating comprises a combination of a basic amino copolymer and a hydrophobic substance of which the melting point is greater than 60"C and/or a polymer which has limited solubility in water. The basic amino copolymer may be obtained, for example, from the reaction of: - a neutral ethylenic monomer such as methyl acrylate or methacrylate, styrene, acrylonitrile or vinyl acetate and, - a diethylenic monomer having a basic nitrogencontaining group such as diethylaminoethyl acrylate or methacrylate, tert-butylaminoethyl acrylate or methacrylate, morpholinoethyl methacrylate or a vinylpyridine.

The hydrophobic substance is preferably a fatty acid, a fatty ester, a fatty alcohol, a paraffin or a natural or synthetic wax. Preferably the hydrophobic substance is stearic acid. The polymer insoluble or of limited solubility in water is generally a cellulose ether or ester such as ethylcellulose or cellulose acetobutyrate, or a polyvinyl ester such as polyvinyl acetate. A composition comprising 85% by weight of amino acid for 15% by weight of coating is preferably employed. The coating generally contains 10 to 30% of basic amino copolymer and from 70 to 90% of a hydrophobic substance and/or a polymer insoluble in water.

The second type of coating which can be used comprises a mixture of a natural polymer such as zein, in combination with a hydrophobic substance having a melting point greater than 600C and/or a polymer insoluble in water. The hydrophobic substance and the water-insoluble polymer may be as described above. A composition containing lo to 90% of zein and 10 to 90% of a hydrophobic substance and/or a polymer insoluble in water is preferably employed.

A plasticizing agent may be added to the above compositions. Suitable plasticizing agents include, in particular, triacetin, propylene glycol, butyl phthalate and sodium oleate.

The coating compositions described above are known, and have been described in European Patent No. 260186 for the first type of composition and in European Patent No.

321337 for the second type of composition.

The protected amino acids are preferably provided in the form of a medicated grain supplement which is fed to the growing lambs generally over a 2 to 3 month period.

Preferably about 0.8 to 2g of amino acid, more preferably about 1.6g of methionine, is administered to a growing lamb per day, the amino acid being given 3 times a week.

It is especially desirable to feed the protected amino acid to the lamb when or before the latter is likely to experience a significant reduction in the standard of its naturally available diet, caused for example by adverse weather conditions. Thus in Australia, with Merino sheep, it is important to build up the liveweight of weaned lambs (preferably to at least 20kg) in advance of the hot dry season which occurs in late summer (February to June). The present invention significantly increases the proportion of lambs in a flock which achieve the desired weight, and thus significantly increases the survival rate of the lambs.

The present invention is illustrated by the following Examples.

EXPERINENTAL DETAILS OF EXAMPLES These Examples provide quantitative data on the effect of a dose rate of 2g product (approximately 1.6g methionine) per head per day, administered as a three times weekly medicated grain supplement. Growing weaner lambs were selected for the trial.

In Australia, most farmers routinely feed oats, wheat, barley or lupins to their weaner lambs over summer.

The trial was therefor focused on feeding protected methionine in a medicated grain supplement to Merino weaner lambs during their first summer.

Fine wool Merio ewe lambs, which were 5 months old at the start of the trial, were used.

In summary, the grain supplements used in this trial had the following characteristics: Oats Lupins Noisture 10.8% 8.7% Dry matter 89.2% 91.3% Crude protein 8.4% 32.2% of dry matter Digestibility 72.3% 84.4% of digestible dry matter Estimated Metabolizable energy 10.6tMJ/kgDN s2.5MJ/kg dry matter The pasture conditions were much better than usual for a typical season with 3084, 3113 and 1876kg/ha dry matter present at the three observation times. The proportion of green matter was 27%, 13% and 14.7% at the three observation times. This is much higher than normal, because of unseasonal rainfall which affected the trial.

The effects of the protected methionine were tested at two different levels of grain supplement at each feed as follows: Oats Lupins Low grain 100g/h + 20g/h per feed High grain 250g/h + 50g/h per feed Since feeding was conducted three times per week the average daily rate of grain supplementation was: Oats Lupins Low grain 43g/h/day + 8.6g/h/day High grain 107g/h/day + 21.4g/h/day These are unusually low rates of grain supplementation compared to the normal industry feed rate of approximately 200-300 gram head/day for supplementary feeding of weaner lambs over the summer.

The dose of protected methionine used was 2g/head/day of product (approximately equivalent to 1.6g/h/day of methionine).

Protected methionine was added to grain by a wet mix technique using liquid molasses as a binding agent as follows: - Measured quantities of oats and lupins were added to a universal feed mixer and mixed for 5 10 minutes. Molasses (3% w/w) was also added to provide a light sticky coating to all grain.

The appropriate quantity of dry protected methionine microspheres was then added slowly and mixing continued for a further 10 minutes to ensure even distribution of the microspheres throughout the grain mix.

- This procedure was repeated with lot sizes sufficient for feeding all groups for 2 or 4 weeks.

Control groups received mixed grain with molasses but without protected methionine.

Mixed feed was fed to the lambs on the day of mixing or stored in bags for up to four weeks before use. No deterioration of feed was noted during storage (e.g. no mould growth, discolouration, odour etc).

The mixed feed was highly palatable and all sheep quickly become accustomed to the feed out procedure.

Measurement of weight and condition score Liveweight was determined using Ruddweigh electronic scales, with an accuracy of + 0.5kg. Condition scores were also assessed subjectively by the same operator on each occasion lambs were weighed.

Marking of wool and measurement of length growth Freshly prepared URSOL-D in hydrogen peroxide was administered to the base (skin level) of a mid flank wool staple on all lambs at the start of each period of the trial.

Wool length growth was therefore determined as follows: Inter dve Dye band segment Phase of trial band Period designation (Days) 51 A Pre treatment period 35 B First phase of treatment 40 C Second phase of treatment (6 weeks) 30 D Post treatment period Length growth between dye bands (mm) was determined by hand measurement using a Vernier calliper. Length measurements were taken on unstretched wool staples.

Sectioning of wool staples and measurement The dye-banded wool staple was removed after the linear measurement of inter dye-band intervals, the staple was sectioned manually into 2mm segments to obtain average fibre diameter for inter dye band intervals A, B, C and D as defined above.

Fibre samples A, B, C and D were separately washed in solvent. Then fibre diameter distribution was determined by a laser based shadow technique (Fibre Diameter Analyser - Gerner Scientific Ltd). In most samples, 2000 determinations of fibre diameter were made in each sample.

Fleece weight Ewe fleece weight was recorded at shearing. These fleece weights represent fleece growth over a 10 month period from birth. During this period the ewes underwent treatment for 10 weeks.

Data were analysed to assess the effect of treatment compared with controls at both levels of grain supplementation.

In addition, a retrospective covariate analysis was conducted of liveweight growth and volume wool growth rate using the following covariates: a. pretreatment liveweight b. body weight growth rate during the pre-treatment period c. fibre volume growth rate during the pre treatment period In the accompanying drawings:: Figure 1 shows the liveweight changes between protected methionine-treated and control lambs fed the low or high grain supplement; Figure 2 shows the differences in growth rate between protected methionine-treated and control lambs fed the low or high grain supplement; Figure 3 shows the distribution of liveweights for protected methionine-treated and control weaners at the pretreatment period, after 4 weeks of treatment, and at the end of 10 weeks of treatment for animals on the low grain diets; Figure 4 shows the distribution of liveweights at various times for the protected methionine-treated and control weaners on the high grain diet; Figure 5 shows the effect of protected methionine treatment on condition score; Figure 6 shows the effect of protected methionine treatment on fleece weights; and Figure 7 shows the effect of protected methionine treatment on the length growth rate of the wool.

WHOLE ANIMAL MEASUREMENTS Example 1 - Liveweight and growth rate Liveweights were not significantly different between groups when measured just prior to the commencement of treatment.

In the period of the first five weeks after start of treatment liveweights increased more rapidly in the treated than control groups regardless of level of grain feed.

Growth rate measured in the same period of the protected methionine-treated high grain group was 24.7% higher than in the control high grain. Growth rate of the protected methionine-treated low grain group over the same period was 18.0% higher than in the control low grain.

Thus, after 4 weeks of treatment, the protected methionine high grain group were heavier than the control although this difference was only significant in the low grain group.

In the second five week treatment period, the rates of growth in the protected methionine-treated groups were also higher than in the control. Growth rate measured in this period was 81.3% higher in the protected methioninetreated high grain group than in the high grain control group.

Growth rate over the same period in the protected methionine-treated low grain group was +19.2g/d compared to a weight loss of -2.49g/d in the control. Thus, by the end of the second five week treatment period, both treated groups were 1.5 to 2.0kg heavier than their respective controls.

By the end of the post treatment period, there was still a significant difference in liveweights in favour of protected methionine-treated compared to control groups.

This advantage was not lost until well after the post treatment period by which time no significant differences in liveweight between groups were apparent.

Graphical representations of these data are shown in Figures 1 and 2.

Example 2 - Distribution of liveweiqhts Growers of merino lambs which are born in spring are very concerned that liveweights of weaners lambs should reach a minimum weight of 20kg before the hot dry period of late summer. Weaners which do not reach this weight suffer high risk of mortality as they are less able to withstand the climatic and nutritional stress over the summer. If the autumn rainfall is late, then these animals are at particular risk.

In this trial, stocking rates were relatively low and both the late spring and early summer pasture during the trial were much better than is normally expected.

Therefore the mean liveweight of the whole flock was generally higher than is normally achieved for spring born lambs in the area of the trial. It was nevertheless of interest to measure the effects of protected methionine treatment on the distribution of liveweights.

It is apparent from Figures 3 and 4 that protected methionine treatment resulted in a shift in the distribution of liveweights towards the higher liveweight categories. This was particularly evident in the reduction (halving) of the occurrence of animals with liveweights in the 20-25kg and 25-30kg categories and an increase (doubling) in the occurrence of animals in the 35-40kg categories. In this experiment, the vast majority of animals exceeded the critical 20kg threshold. However, the same shift in frequency distribution is to be expected in lighter flocks, so that the protected methionine treatment has considerable potential as a natural method for enhancing weaner growth and increasing weaner survival over the summer period.

The achievement of 18 to 81% increases in growth rates during the treatment period is of considerable importance, and supports the use of the product to enhance growth rates of lambs.

Example 3 - Effect on condition score of weaner ewe lambs In addition to the positive effects of treatment on growth rate and liveweight, there were also significant effects of treatment on condition score.

Prior to treatment there were no significant difference in condition scores between groups. 4 weeks after the start of treatment the condition scores of the protected methionine-treated ewe lambs were significantly higher than in the respective untreated control groups.

This difference was maintained 10 weeks after the start of treatment, and continued until one month after treatment.

These differences were sufficient to be noticeable by skilled stock handlers in the field, who frequently commented that the treated animals were in better condition than the controls. This is important to farmers who like to see their animals growing well, or at the very least, maintaining condition over the difficult conditions of summer and autumn.

Condition score data are shown graphically in Figure 5.

Example 4 - Effect of protected methionine on fleece weights The greasy fleece weights were obtained at shearing and represent approximately 10 months of fleece production from birth. Weights include the whole fleece prior to skirting but do not include belly wool which is removed on the shearing board. Belly weights were recorded from a sample of 23 animals in each group and were not significantly different.

Treatment was applied over a period of approximately 10 weeks of the total 10 month growth period. Protected methionine treatment significantly increased greasy fleece weight in weaners on both the low and high grain diets.

Increases in fleece weight were 220g/hd (9.1%) for animals on the low grain diet and 180g/hd (7.3%) for animals on the high grain diet.

These data are presented graphically in Figure 6.

DYNAMICS OF FIBRE GROWTH ON DYE BANDED STAPLES Example 5 - Linear arowth and linear arowth rate Absolute distances (mm) between the front edges of successive dye bands were measured in duplicate for 150-200 animals in each group. Length growth rates (mm/day) were calculated by dividing the absolute distances by the number of days between the application of each dye band.

Wool length growth was not significantly different between grain feed levels or protected methionine treatment groups during the pretreatment observation period.

Feeding of protected methionine resulted in a significant increase in the absolute wool length and wool length growth rate measured during the first 4 weeks of treatment. In the low grain group the increase was 6.0% above control, while in the high grain group it was 5.8% above control.

These stimulatory effects increased in the second phase of treatment. Thus during the last 6 weeks of treatment, the protected methionine-treated weaners on low grain grew 8.1% more wool length than their respective controls and the protected methionine-treated weaners on high grain grew 10.5% more wool length than their respective controls.

The effect of the treatment on the length growth rate of wool for weaners on low and high grain diets is shown in Figure 7.

Example 6 - Effect of protected methionine treatment on mean tensile strength of weaner wool (a) Fleece grown only during treatment period In order to evaluate the effects of protected methionine supplementation on the wool grown during the treatment period, the fleece samples were tested by clamping the staple at DB2 and DB4. Thus tensile strength of wool grown only during the treatment period was tested.

In this second analysis, protected methionine treatment was shown to increase tensile strength by 9.9% (+4.25 N/ktex) in the low grain group and by 2.1% (0.97 N/ktex) in the high grain group. Although not significant within grain groups, this effect was almost significant when the results for both nutrition levels were pooled.

Although the effect was quantitatively small because of the relatively good tensile strength of fleeces in this trial, it is probable that this effect would be important in fine wool fleeces which otherwise have a nutritionrelated fibre weakness.

COVARIATE ANALYSIS Example 7 - Adjustment for pre-treatment liveweight and growth rates Examination of the data of Figures 1 and 2 showed minor differences in liveweights and liveweight growth rate between treated and control lambs during the period just prior to the commencement of treatment.

In order to test whether such differences could have confounded interpretations of treatment effects at later times, the statistical analysis has been repeated using the pre-treatment growth or pre-treatment liveweight as the covariate. Prior to using each covariate, tests were conducted for the presence of interactions and for homogenicity of slopes. No interactions were identified.

The covariate analysis confirmed that the effect of treatment on increasing growth rates was statistically significant regardless of whether pre-treatment liveweight or growth rates are used as covariates.

Claims (20)

1. A method for increasing the liveweight of a lamb which comprises feeding to a growing lamb a diet comprising an effective amount of a protected amino acid.

2. A method for increasing wool production in a lamb which comprises administering an effective amount of a protected amino acid to a growing lamb.

3. A method for increasing the growth rate of wool in a lamb which comprises administering an effective amount of a protected amino acid to a growing lamb.

4. A method for increasing the quality of wool produced by a lamb which comprises administering an effective amount of a protected amino acid to a growing lamb.

5. A method for increasing-the fibre length of wool produced by a lamb which comprises administering an effective amount of a protected amino acid to a growing lamb.

6. A method for increasing the fibre tensile strength of wool produced by a lamb which comprises administering an effective amount of a protected amino acid to a growing lamb.

7. A method according to any one of claims 1 to 6, wherein the lamb is a weaner lamb.

8. A method according to claim 7 wherein the lamb is a Merino ewe lamb.

9. A method according to any one of the preceding claims, wherein the effective amount of amino acid is about 1.6 grams per lamb per day.

10. A method according to claim 9 whereas the amino acid is administered to the lamb three times a week.

11. A method according to any one of the preceding claims, wherein the amino acid is methionine or lysine.

12. A method according to any one of claims 1 to 10 wherein the amino acid is methionine.

13. A method according to any one of the preceding claims, wherein the amino acid is protected by a polymer which is resistant to alkaline pH but liberates the amino acid at acid pH or in the intestine.

14. A method according to any one of claims 1 to 12, wherein the amino acid is protected by a layer comprising a basic amino copolymer and a hydrophobic substance of which the melting point is greater than 60"C and/or a polymer insoluble in water.

15. A method according to any one of claims 1 to 12, wherein the amino acid is protected by a layer comprising zein and a hydrophobic substance of which the melting point is greater than 60"C and/or a polymer insoluble in water.

16. A method according to claim 14, wherein the amino acid is protected by a layer comprising a styrenevinylpyridine copolymer in association with a hydrophobic substance, and a polymer insoluble in water.

17. A method according to claim 14, 15 or 16 wherein the hydrophobic substance is stearic acid.

18. A method according to claim 14, 15 or 16 wherein the polymer insoluble in water is ethylcellulose.

19. A method according to any one of claims 1 to 6, substantially as described in any one of the foregoing Examples.

20. Wool whenever obtained from a lamb treated by a method according to any one of the preceding claims.