Livestock Production Science 64 (2000) 291–294
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Short communication
The effect of degree of grass wilting prior to ensiling on
performance and energy utilisation by lactating dairy cattle
a,b,c ,
*
a,b,c a b,cF.J. Gordon
, D.C. Patterson
, M.G. Porter , E.F. Unsworth
a
Agricultural Research Institute of Northern Ireland, Large Park, Hillsborough, Co. Down BT26 6DR, Northern Ireland, UK
b
Department of Agriculture for Northern Ireland, Newforge Lane, Belfast BT9 5PX, Northern Ireland, UK
c
The Queen’s University of Belfast, School of Agriculture and Food Science, Newforge Lane, Belfast BT9 5PX, Northern Ireland, UK
Received 5 January 1999; received in revised form 20 July 1999; accepted 29 July 1999
Abstract
Thirty lactating Holstein Friesian cows were used in a three treatment randomised block design experiment to investigate the influence of degree of grass wilting prior to ensiling on animal performance and energy utilisation. The three forage treatments were produced from perennial ryegrass swards either ensiled directly or mown, conditioned, spread and tedded to ensure rapid wilting, and ensiled following 30 or 52 h to achieve dry matter (DM) concentrations in the silages of 193, 286 and 437 g / kg respectively. All silages were offered in ad libitum quantities for a 5-week period and in addition all cows received 10 kg / d of a concentrate containing 206 g CP/ kg DM. Total diet digestibility data were recorded on four cows / treatment and methane outputs on two cows / treatment during the final week of the experiment. The daily intake of silage DM increased with increased wilting – 7.2, 7.3, and 8.4 (s.e.m. 0.44) kg DM – but milk yield was highest with the unwilted silage – 23.3, 20.5 and 21.7 (s.e.m. 0.80) kg / d – for the unwilted, medium and high levels of wilting respectively. Wilting had no effect on the yield of milk fat or protein but the nutrient utilisation studies suggested that the overall efficiency of metabolisable energy conversion to milk energy output was reduced with increasing degree of wilting.
2000 Elsevier Science B.V. All rights reserved.
Keywords: Ensiling; Wilting; Lactating cows; Animal performance; Digestibility
1. Introduction 1989). While wilting generally increased DM intake
it often marginally reduced milk output and resulted The effects of wilting on dry matter (DM) intake in considerable reductions in the output of beef and and animal production, including the output of dairy product per unit area of land. However none of animal product / ha, have been the subject of consid- these studies have adopted the recently developed erable research, (see reviews by Marsh, 1979; Wil- techniques for ensuring fast rates of crop drying in kins, 1984; Unsworth and Gordon, 1985; Gordon, the field (Patterson, 1993) and which now offer opportunities to achieve much higher DM concen-trations in silages. The present study was therefore *Corresponding author. Tel.: 144-1846-682-484; fax: 1
44-1846-689-594. established to examine the effect of a range of
292 F.J. Gordon et al. / Livestock Production Science 64 (2000) 291 –294
degrees of wilting, using enhanced in-field wilting the feeding experiment, which commenced after the techniques, on intake, performance and energy utili- forages had been 56 days ensiled, the three silages sation by dairy cattle. were offered in sufficient quantity to allow pro-portionally 0.05 in excess of intake. All cows were also offered 10 kg / d of a dairy concentrate. For 2. Material and methods those cows entering the experiment at calving con-centrate intake increased linearly from 2 kg on day 1 The three silages used in the study were produced to 10 kg on day 15 of lactation. The concentrate as the second annual harvest from perennial ryegrass used, contained 250, 200, 167, 167, 141, 25, 25 and swards (cv. Talbot) during mid-August. On day 1 the 25 g / kg of maize gluten, barley, sugar beet pulp, grass was mown with a mower conditioner (Taarup citrus pulp, soyabean meal, fish meal, protected fat Model 307). Within 30 min of mowing one third of (Megalac) and minerals, respectively.
the crop was lifted for ensiling and the remainder A total of 12 cows, four blocks of three, were spread to maximise the rate of drying. Twenty six transferred to individual standings during week five hours later the grass was tedded, to facilitate further of the experiment for a six day diet digestibility and drying, and then at 30 h post-cutting half of the N balance study. The equipment, procedures and remaining grass was ensiled. At 48 h after cutting the analytical methods were as described by Gordon et remaining grass was tedded and ensiled at 52 h al. (1995). At the end of this balance study six cows, post-cutting. The same precision chop harvester two blocks of three cows, were transferred to indirect (Mengele Model SH40) was used throughout and all open-circuit respiration chambers for measurement grass was ensiled in concrete walled bunker silos. An of methane production. Cows remained in these inoculant additive (‘Ecosyl’, Zeneca Bioproducts chambers for three days with methane output re-Ltd.) was applied at 3.0 kg / t fresh crop to all grass at corded over the final 48 h. The equipment, pro-ensiling. There was no rainfall throughout the 52 h cedures and analytical methods were as described by wilting period. Gordon et al. (1995).
Thirty lactating Holstein Friesian dairy cattle, 18 Silage was sampled daily throughout the feeding in their first and 12 in their second lactation, were period. Milk yields were recorded daily and milk used in a randomised block design feeding study. samples taken on days 5, 6 and 7 of the 5th week of The cows were housed as a single group in cubicle the experiment, and the 4th week of the post accommodation with the forages offered in troughs experiment standardisation period. Live weights fitted with automatic weighing equipment and an were recorded weekly during the experiment, and on entry door which was activated by a transponder week four of the post experiment standardisation fitted to each cow. All concentrates, with the excep- period. The methods of forage, concentrate and milk tion of 1 kg / d, were offered through an out-of- sampling and analysis were as described by Gordon parlour feeding system on the basis of four equal et al. (1995).
feeds daily. The additional 1 kg concentrate was All cow production and feed digestibility data divided over two feedings and offered during milk- were statistically analysed as a randomised block ing at 07.00 and 16.30. Twelve of the cows were 36 using milk production data recorded on week four of (s.d. 19.6) days calved at the commencement of the the post-experimental period and liveweight at the study and the remainder entered the study directly on beginning of the study as covariates.
calving. Cows were blocked into groups of three according to calving date and parity and allocated at
random within each block to the three silage feeding 3. Results treatments.
F.J. Gordon et al. / Livestock Production Science 64 (2000) 291 –294 293
Table 1
Effect of extent of wilting on silage composition, feed intake, cow performance and nutrient utilisation (intake and performance data relate to 10 cows / treatment, digestibility to four cows / treatment and energy utilisation to the mean of 10 cows / treatment using ME concentrations
a
derived from the digestion studies)
Silage DM concentration S.E.M. Significance
Low Med High
Silage composition
a b c
Dry matter (g / kg) 193 286 437 6.0 ***
Crude protein (g / kg DM) 123 127 123 2.1 NS
a b b
PH 3.7 3.9 4.0 0.04 ***
NH N (Prop total N)3 0.07 0.08 0.08 0.004 NS
a b c
Ash (g / kg DM) 85 97 90 1.5 ***
a b c
Lactic acid (g / kg DM) 93 70 50 3.9 ***
a b c
WSC (g / kg DM) 14 44 114 5.9 ***
Silage DMI (kg / d) 7.2 7.3 8.4 0.44 P,0.10
Concentrate DMI (kg / d) 8.6 8.6 8.6
a b a,b
Milk yield (kg / d) 23.3 20.5 21.7 0.80 *
Milk composition (g / kg)
Fat 40.4 43.0 43.5 1.31 NS
Protein 31.6 31.8 30.8 0.67 NS
Yield of milk components (g / d)
Fat 928 899 950 48.8 NS
Protein 723 655 677 30.8 NS
Fat1protein 1652 1554 1626 76.6 NS
Liveweight (kg) 512 520 527 14.1 NS
Digestibility of total diet
Dry matter 0.755 0.743 0.757 0.0062 NS
a,b b a
Gross energy 0.743 0.734 0.753 0.0055 *
Nitrogen 0.698 0.667 0.666 0.0100 P,0.10
Utilisation of energy
Diet ME concentration 11.93 11.58 11.67 0.124 NS
(MJ / kg DM)
ME intake (MJ / d) 188 184 198 – –
Milk energy (MJ / d) 73 66 70 – –
a
Milk energy based on E(MJ / d)50.0384 [B]10.0223 [P]10.0199 [La] 0.108 (Tyrrell and Reid, 1965). ME concentration derived from energy digestibility determined from four cows / treatment and CH4 energy losses (proportion of gross energy intake) from two cows / treatment. Means with different subscripts within rows are significantly different at 5% level.
final week of the experimental feeding period. There higher with high than the medium degree of wilt was a non-significant (P,0.10) trend towards in- (P,0.05).
creasing silage DM intake as DM concentration increased but milk yield was the highest with the
lowest DM forage and the lowest with the medium 4. Discussion DM, this difference being significant at P,0.01.
There were no significant differences in milk fat or The crop drying rates achieved in the present in protein concentration, or the daily output of fat study were considerably faster than those recorded plus protein. during the major proportion of previous wilting The data on digestibility of the diets are also studies at this Institute and hence provided data presented in Table 1. There were no significant relevant to the higher rates of wilting which can now differences between treatments in terms of DM or N be achieved in practice.
294 F.J. Gordon et al. / Livestock Production Science 64 (2000) 291 –294
286 g DM / kg to increase DM intake by 1.4% a (k ), or greater partitioning of ME intake towardsl response which is close to the overall mean of 0% body tissue gain. The present study does not provide reported from a review of 39 studies by Wilkins adequate data to enable these possible mechanisms to (1984) following moderate degrees of wilting. How- be disentangled.
ever at the highest DM concentration (437 g DM / kg) in the present study the response in intake at
16.6% was much greater. Other research, in which a Acknowledgements range of DM concentrations have been produced, has
also shown similar trends with increasing responses The authors would like to thank the staff of in intake as DM concentration increased up to Agricultural Research Institute of Northern Ireland approximately 400 g / kg (O’Kiely et al., 1988). The and The Agricultural and Environmental Science present data would therefore support the hypothesis Division of Department of Agriculture for Northern that provided wilting is being achieved rapidly the Ireland for their support throughout this study. response in intake will increase with degree of
wilting, up to at least 450 g DM / kg.
In the present study wilting resulted in a mean References reduction in milk yield of 9%, this depression
tending to be the greatest with the medium DM Gordon, F.J., 1989. Effect of silage additives and wilting on animal performance. In: Haresign, W. (Ed.), Proceedings of material. However because of the trend towards
23rd Feed Manufacturers’ Conference, University of Nottin-higher butterfat concentration with both wilted
ma-gham, Butterworths, London, pp. 159–173.
terials, the outputs of fat plus protein were not Gordon, F.J., Porter, M.G., Mayne, C.S., Unsworth, E.F., Kilpat-significantly influenced by wilting; the mean effect rick, D.J., 1995. Effect of forage digestibility and type of of wilting was to reduce the outputs of milk fat plus concentrate on nutrient utilisation by lactating dairy cattle. J.
Dairy Res. 62, 15–27. protein by 3.8%. This mean effect of wilting on the
Marsh, R., 1979. The effects of wilting on fermentation in the silo output of milk components was relatively similar to
and on the nutritive value of silage. Grass Forage Sci. 34, 1–9. the 3% reduction reported by Gordon (1989) as a O’Kiely, P., Flynn, A.V., Wilson, R.K., 1988. A comparison of the mean of eight similar studies at this Institute but chemical composition of unwilted and wilted grass silage and contrasts with recent work by Patterson et al. (1996) of the intake, performance, carcass composition and rumen fluid volatile fatty acid concentrations of steers fed the silages. where significant positive responses were obtained
Irish J. Agric. Res. 27, 39–50. from wilting over three harvests.
Patterson, D.C., 1993. The effects of grass and swath treatment Unsworth and Gordon (1985) summarised data factors on the rate of drying silage grass. In: Silage Research from four previous studies and reported either no or 1993 – Proceedings of the 10th International Conference on only marginal effects of wilting on the digestibility Silage Research, Dublin, pp. 51–52.
Patterson, D.C., Yan, T., Gordon, F.J., 1996. The effects of wilting of energy in mixed diets with dairy cattle. This was
of grass prior to ensiling on the response to bacterial inocula-in linocula-ine with the present study. However these effects
tion. 2. Intake and performance by dairy cattle over three on mixed diets are often masked by the inclusion of harvests. Anim. Sci. 62, 419–429.
supplementary feeds and numerous authors have Tyrrell, H.F., Reid, J.T., 1965. Prediction of the energy value of shown considerable depressions in the digestibility of cows milk. J. Dairy Sci. 48, 1215–1223.
Unsworth, E.F., Gordon, F.J., 1985. The energy utilisation of energy in silage only diets following wilting
(Un-wilted and un(Un-wilted grass silages by lactating dairy cows. In: sworth and Gordon, 1985). Linking the data from the
58th Annual Report of the Agricultural Research Institute of digestion and production elements of the present Northern Ireland, pp. 13–20.
study would provide support for the view that wilting Wilkins, R.J., 1984. A review of the effects of wilting on the reduces the efficiency of ME conversion to milk composition and feeding values of silages. In: Zimmer, E., Wilkins, R.J. (Eds.), Efficiency of silage systems: a comparison energy output – an effect which appears to increase
between wilted and unwilted silages. Landbauforschung Vol-with degree of wilting. This could arise through
kenrode, 69, pp. 5–12. either effects on maintenance energy requirements,
