Effects on cow performance and milk fat composition of feeding full fat soyabeans and rapeseeds to dairy cows at pasture

LivestockProductionScience 44 ( 1995) 13-25

Effects on cow performance and milk fat composition of feeding full fat soyabeans and rapeseeds to dairy cows at pasture J.J. Murphy”,*, J.F. Connollyb, G.P. McNeillb “Production Research and Development Centre, Teagasc, Moorepark Research Centre, Fermoy, Co. Cork Ireland bDairy Products Centre. Teagasc, Moorepark Research Centre, Fennoy, Co. Cork, Ireland

Accepted22 May 1995

Abstract Three experiments were undertaken where the effects of feeding full fat soyabeans (FFS) and full fat rapeseeds (FFR) on milk fat composition and cow performance were studied. In Expt. 1, four groups of 15 cows each, on pasture, were put on the following supplementation treatments, (1) none (control), (2) 1.6 kg/cow/day FFS (1.6 FFS), (3) 3.2 kg/cow/day FFS (3.2 ITS), and (4) 3.2 kg/cow /day soyabean meal (3.2 SBM) , for 11 weeks. Milk yield, milk constituent yield or milk composition were not signifiantly different between treatments. The fatty acid composition and solid fat content of the milk fat were similar on the control and 3.2 SBM treatments. However, feeding both levels of FFS significantly decreased the proportions of C6:O (PO.OOl), protein yield (P < 0.001) and lactose yield (P < 0.001). Milk fat concentration was significantly reduced (P < 0.001) by the supplements. Feeding both FFR supplements significantly reduced the proportions in milk fat of C4:O (P
Fat composition;Full fat rapeseed;Soyabean

* Corresponding

author

0301-6226/95/$09.50 0 1995 SSDlO301-6226(95)00048-8

Elsevier Science B.V. All rights reserved

14

J.J. Murphy et al. /Livestock

Production Science 44 (1995) 13-25

Introduction

Previous work has shown that it is possible to alter the fatty acid composition of milk fat, when cows are indoors on silage based diets, by feeding different fats and oils or oilseeds (Banks, 1987; De Peters et al., 1985; Handy and Kennelly, 1983; Perry and MacLeod, 1968; McGuffey and Schingoethe, 1982; Murphy et al., 1990, 1995). However, a high proportion of milk for product manufacture in Ireland, the UK, Northern Europe and New Zealand is produced when cows are at pasture. Milk fat produced at pasture compared to indoors is generally softer and has a higher content of C18:l andalowercontent ofC16:Owhichis areflection of the high proportion of C 18 fatty acids in grass. Butter made from milk fat produced at pasture, though softer than that from milk fat produced indoors (Cullinane et al., 1984)) is still not spreadable at refrigeration temperatures. However, its higher C 18: 1 content is beneficial from a nutritional point of view (Mattson and Grundy, 1985). Thus, further increasing the Cl 8: 1 content, reducing the C 16:Oand increasing the softness of the milk fat at refrigeration temperatures could further enhance the consumer acceptability of milk fat produced at pasture. Therefore, three experiments were undertaken where full fat soyabeans (FFS) and full fat rapeseeds (FFR) were fed to cows at pasture at levels which had previously given significant effects on the fatty acid composition and softness of milk fat produced indoors (Murphy et al.; 1990, 1995). The objectives were to increase further the Cl 8: 1 content and softness of the milk fat over and above what had been achieved indoors and determine whether longer term supplementation at pasture had any negative effects on cow performance.

2. Materials and methods Three experiments were carried out where FFS (Expt. 1) and FFR (Expts. 2 and 3) were fed to dairy cows on pasture. 2.1. Experiment 1 Sixty cows of 2nd parity or greater which had calved between January and April were blocked into groups of four on the basis of calving date and current milk

yield and then assigned at random to one of four treatments: 1. Pasture only (control). 2. Pasture plus 1.6 kg/day FFS ( 1.6 FFS). 3. Pasture plus 3.2 kg/day FFS (3.2 FFS). 4. Pasture plus 3.2 kg/day soyabean meal (3.2 SBM) . All cows were grazed together at a stocking rate of 0.33 ha per cow from mid-July and the supplements were fed for 11 weeks from the end of July until midOctober. The FFS had undergone a ‘toasting’ process which involved cracking of the seeds, steam treatment, flaking and cubing. The composition (g/kg) of the FFS and SBM fed was, dry matter 889 and 874, crude protein 392 and 483, oil 210 and 19 and ash 56 and 62, respectively. The supplements were fed once per day before the evening milking. Milk yields were measured on 5 days per week and milk composition, fat, protein and lactose was measured on successive pm and am samples taken once weekly. Individual cow milk samples were taken at am and pm milkings 12 and 5 days before supplementation commenced (day 0) and on days 1,2,3,9,16,23,30, 37, 44, 51, 58 and 65 after supplementation commenced. These samples were cornposited to give one bulk sample per treatment per time for fatty acid profiles and solid fat content at different temperatures. In the 9th week individual cow milk samples from successive am and pm milkings were taken once and composited according to yield to give one daily sample per cow. The fatty acid and triglyceride composition as well as the solid fat content at different temperatures in the milk fat was determined in these samples. 2.2. Experiment 2 Forty-five cows which had calved between January and March were blocked into groups of three on the basis of calving date and milk yield and assigned at random to one of three treatments: 1. Pasture only (control). 2. Pasture plus 3.0 kg/day low FFR concentrate (low FFR). 3. Pasture plus 3.0 kg/day high FFR concentrate (high FFR). The ingredient and chemical composition of the low and high FFR concentrates are shown in Table 1. All cows were grazed together at a stocking rate of 0.24 ha per cow. Supplementation commenced on July 17th

J.J. Murphy et al. /Livestock Production Science 44 (1995) 13-25

and lasted for 8 weeks. Due to low rainfall during this period grass growth was poor and all cows were given a supplement of 3.0 kg per day (after the morning milking) of grass nuts from week 2 to 7 inclusive. The FFR supplements were fed once per day after the evening milking. Milk yield was measured on 3 days per week and milk samples were taken on successive pm and am milkings once weekly for fat, protein and lactose analysis. Individual cow milk samples were taken at am and pm milkings 5 and 3 days before supplementation commenced, on the day supplementation commenced (day 0) and on days 1,2,3,9,16,23,30,37, 44 and 51 after supplementation commenced. These samples were composited by treatment daily and the milk fat was analysed for fatty acid profiles and solid fat content at different temperatures. Morning and evening milk samples were also cornposited by cow on days 23,37 and 5 1 after supplementation commenced and the milk fat was analysed as before. 2.3. Experiment 3 The main purpose of this experiment was to examine the effect of longer term supplementation with FFR on general cow performance and health. Sixty-six cows were blocked into pairs on the basis of calving date, lactation number and milk yield. One of each pair was then randomly assigned to one of two treatments: Table 1 The ingredient

(kg/tonne)

and chemical composition

(g/kg

1. Control. 2. FFR supplemented (FFR) . Twenty-two cows per treatment were put on experiment on March 12th and eleven cows per treatment were put on experiment on April 3rd. Cows were fed 6 kg of concentrates per day, while indoors on silage, of which 3 kg consisted of FFR supplement for the FFR group. After turn-out to pasture on March 26 concentrate supplementation was slowly reduced to 3 kg of FFR supplement for the PFR group and to zero concentrates for the control group. This regime was maintained until the end of lactation. The ingredient composition and chemical analysis of the FFR supplement is shown in Table 1. The treatments were imposed on average 21 days (range 114l) after calving and were terminated on October 30th when cows were dried off and were on average 242 days into lactation. Milk yield was measured daily, milk composition (fat, protein and lactose) on successive AM and PM samples once every 2 weeks, total fatty acid profiles and solid fat content of the milk fat on one AM and PM composite sample by treatment every 2 weeks and blood metabolic profiles on one sample monthly. The fertility performance of the groups was monitored. The breeding season commenced on April 29 at which stage 44 cows (22 per treatment) were on experiment for 48 days and 22 cows ( 11 per treatment) were on experiment for 26 days. Somatic cell counts (SCC) were measured in one

DM) of the FFR supplements

fed in Expts. 2 and 3 Expt. 3’

Expt. 2

Unmolassed sugar beet pulp Full fat rapeseed Molasses Dicalcium phosphate Limestone flour Chemical composition Dry matter (g/kg) Crude protein Oil Crude fiber Ash

15

Low FFR

High FFR

675 275 50

400 550 50

_

_

15 5

892 137 119 159 55

903 175 226 130 61

887 163 255 128 70

430 550

‘The following trace mineral/vitamin supplement was added per tonne of supplement in Expt. 3: ferrous sulphate 145 g; manganous oxide 80 g; copper sulphate 200 g; zinc oxide 50 g; potassium iodate 8 g; sodium selenite 2 g; cobalt sulphate 6 g; vitamin A 8 m.i.u.; vitamin D3 2 m.i.u.; vitamin E 5000 i.u.

16

J.J. Murphy et al. /Livestock

Production Science 44 (1995) 13-25

AM milk sample bi-weekly between May and September (total of eight samples per cow). 2.4. Sample analysis All feedstuffs were analysed by standard procedures. Milk composition was determined by automated infrared analysis using a Milkoscan 203 (Foss Electric, Denmark). For detailed fat analysis, cream was obtained by centrifugation and held at - 18°C overnight. The cream was warmed to 60°C for 10 min and centrifuged to obtain the milk fat. The fatty acid composition and the solid fat content at selected temperatures were measured according to the procedures outlined by Murphy et al. ( 1995). Triglyceride composition of the fat was determined as described by Murphy et al. ( 1990). Blood serum was analysed using a COBAS MIRA biochemical analyser (Roche Diagnostics). Milk was analysed for somatic cells using a Fossomatic 180 automatic cell counter (AS/N Foss Electric, Denmark). 2.5. Statistical analysis In the experiments milk yield, constituent yield and composition were analysed by the GLM procedure of SAS 6.04 using data from the two pre-experimental weeks, lactation number and calving day as covariates in Expt. 1 and data from the immediate pre-experimental week, lactation number and calving day as covariates in Expts. 2 and 3. Fatty acids, triglycerides and the solid fat content at different temperatures in the milk fat of individual cows and blood metabolites were

analysed by the GLM procedure of SAS 6.04 without covariates. Statistical differences between treatment means were determined using Student’s t-test. In Expt. 3 calving to service and calving to conception intervals were compared using a t-test and percent infertile and services per conception for conceived and served cows were compared using a Chi-square test.

3. Results 3.1. Experiment I

The effect on cow performance of supplementing cows at pasture with FFS and SBM is shown in Table 2. Feeding 1.6 kg and 3.2 kg of FFS and 3.2 kg of SBM numerically increased the yield of milk, fat, protein and lactose compared to the control but none of the differences were statistically significant. Also, fat, protein and lactose concentrations in milk were not significantly different between treatments. The fatty acid composition of the milk fat on the control and SBM supplemented cows was similar (Table 3). Only C18:2 which makes up a small proportion of the total fatty acids was significantly higher on the 3.2 kg SBM than the control. However, feeding both levels of FFS significantly decreased C6:O (P
Table 2 Effect of supplementing cows at pasture with FFS and SBM on milk yield, and milk constituent yield SE of diff.’

Treatment

Milk yield (kg/day) Fat yield (g/day) Protein yield (g/day) Lactose yield (g/day) Fat (g/kg) Protein (g/kg) Lactose (g/kg)

control

1.6kg FFS

3.2 kg FFS

3.2 kg SBM

14.7 539 494 619 37.5 34.1 41.8

15.3 565 521 646 37.8 34.7 41.8

15.2 558 498 641 38.1 33.7 41.6

15.7 566 527 656 36.9 34.4 41.3

‘SE of diff. = standard error of difference.

0.66 37 22 36 1.97 1.25 1.24

J.J. Murphy et al. /Livestock Production Science 44 (1995) 13-25 Table 3 Effect of supplementing

cows at pasture with FFS and SBM on the fatty acid composition

(g/kg

17

total fatty acids) of milk fat in Expt. 1

Treatment -

c4:o C6:O C8:O c1o:o c12:o c14:o C14:l C16:O C16:l C18:O C18:l C18:2 C18:3

SE of diff.’

control

1.6kg BBS

3.2 kg FFS

3.2 kg SBM

25.1 18.8a’ 11.7” 25.6” 31.7” 111.1” 18.9a 238.2” 25.5 110.9” 285.5” 18.3” 6.6”

23.2 16.1b 9.4b 19.3b 23.2’ 85.1b 13.1b 20 1.3b 21.9 141 .Ob 343.1b 33.2b 8.3b

25.1 15.9” 8.8” 17.5” 20.3” 74.2’ 11.6h 197.2” 21.8 141.5” 350.gh 47.6’ 8.7”

26.4 19.9a 12.7” 28.3” 34.3” 110.2” 18.8a 243.7” 26.4 103.5” 280.5” 23.2“ 7.7”

‘SE of diff. = standard error of difference. + Within rows, means not sharing a common superscript

differ significantly

Cl 8:2 (P < 0.001) in the milk fat. The C4:O content of the milk fat was unaffected by the treatments. The triglyceride composition of the milk fat is shown in Table 4. Supplementing with FFS significantly decreased the C30 to C48 triglycerides (P < 0.05) with the exception of C40, the decrease being greater for the C32, C34 (P
1.2 0.8 0.6 1.4 1.7 3.4 1.3 7.2 1.0 6.8 7.7 2.2 0.6

(P< 0.05).

ments had a higher solid fat content in the milk fat than the control (P < 0.05). The changes in the levels of C16:0, C18:l and solid fat content at 10°C in the milk fat with time, due to the treatments, are shown in Fig. 1. Before introducing the supplements the levels of C16:0, C18: 1 and solid fat were similar. On day 1 after introduction the proportion of C16:O was about 250 g/kg fatty acids in all treatments but by day 3 it had dropped to 218 and 208 on the 1.6 kg ES and 3.2 kg J?FS treatments, while being 239 and 254 on the control and 3.2 kg SBM, respectively. Subsequently the proportion remained similar on the control and 3.2 kg SBM groups and was lower by 30 to 40 g/kg fatty acids on both FFS groups. The reverse pattern was evident for C 18: 1. The proportion of C 18: 1 tended to be lower on the 3.2 kg SBM treatment compared to the control particularly on days 44, 5 1 and 58, whereas the 1.6 kg FFS and 3.2 kg FFS had higher proportions than the control with the 3.2 kg FRS being higher than the 1.6 kg FFS. The solid fat content at 10°C was similar on all treatments 12 and 5 days before supplementation and 1 day after supplementation. The general pattern subsequently was that the level was similar on the control and 3.2 kg SBM treatments and was lowest on the 3.2 kg FFS treatment with the 1.6 kg FFS being intermediate.

18

J.J. Murphy et al. /Livestock Production Science 44 (1995) 13-25

Table 4 Effect of supplementing cows at pasture with BBS and SBM on the triglyceride composition (g/kg fat) of milk fat in Expt. 1 Triglyceride carbon number

26 28 30 32 34 36 38 40 42 44 46 48 50 52 54

Treatment

SE of diff.’

control

1.6kg BBS

3.2 kg FFS

3.2 kg SBM

l.5p+ 4.5’ 8.8” 19.7” 44.5” 84.0” 115.4” 104.3= 68.6” 58.4’ 72.8’ 99.7” 129.1” 117.4” 66.7”

1.5” 4.3” 7.4b 15.1b 33.3b 67.9b 108.3b 114.3b 58.6b 45.7b 58.8b 81.8b 128.7” 148.8b 121.3b

1.4” 3.9b 6.4b 12.8” 28.5’ 62.4b 108.Sb 117.9b 56.7b 42.3’ 54.00-

2.1b 5.7c lo.4d 21.5” 47.5’ 87.7a 120.1a 108.7’ 71.3a 62.0’ 74.9a 94.1C l18.3b lo7.3a 64.1a

77.5b 126.1” 159.1b 139.5c

0.2 0.3 0.5 0.9 1.8 2.9 2.8 2.8 1.9 2.2 2.4 2.7 2.8 5.3 2.7

‘SE of diff. = standard error of difference. +Within rows, means not sharing a common superscript differ significantly (PC 0.05). Table 5 Effect of supplementing cows at pasture with FFS and SBM on the solid fat content (g/kg fat) at different temperatures in milk fat in Expt. 1 Temperature PC)

0 5 10 15 20 25 30

Treatment

SE of diff.’

control

1.6 kg FFS

3.2 kg FFS

3.2 kg SBM

532.0”+ 479.0” 402.0’ 251.0” 129.0 68.0” 18.0”

468.0b 414.0b 338.0b 226.0ab 127.0 68.0” 29.0b

444.0b 383.F 299.v 214.ob 121.0 64.0” 28.0b

518.0’ 465.V 383.0a 234.P 121.0 56.ob 140

13.9 15.0 15.1 12.7 8.3 5.7 3.7

‘SE of diff. = standard error of difference. +Within rows, means not sharing a common superscript difer significantly (P < 0.05).

3.2. Experiment 2 The effect. on cow performance of supplementing cows at pasture with 3.0 kg of concentrates containing 275 and 550 g/kg of FFR is shown in Table 6. Milk yield was significantly increased on the low and high FFR treatments (P < 0.001) compared to the control. It was significantly higher on the low FFR compared

to the high FFR treatment (P ~0.05). Fat yield was significantly increased by the low FFR (P < 0.05) and significantly reduced by the high FF’R supplement (P < 0.05). Both protein and lactose yields were significantly increased by both supplements (P < 0.001)) the increases being numerically greater on the low FFR supplement in both cases. Milk fat concentration was significantly reduced by the supplements (P < 0.001) , protein concentration was unaffected and lactose con-

.I.J. Murphy et al. /Livestock

Table 6 The effect on milk yield, milk constituent Expt. 2

Production Science 44 (1995) 13-25

yield and milk composition

of feeding 3.0 kg/day

19

of a low and high FFR concentrate

Treatment

Milk yield (kg/day) Fat yield (g/day) Protein yield (g/day) Lactose yield (g/day) Fat (g/kg) Protein (g/kg) Lactose (g/kg)

Table 7 The average fatty acid concentrations FFR at pasture in Expt. 2 Fatty acid

(g/kg

low FFR

high FFR

12.7”’ 480” 435” 551” 38.3” 34.7 43.2”

15.0s 509s 511b 664b 34.2b 34.2 44.1b

14.2’ 453” 492b 632b 32.3’ 34.9 44.4s

Table 8 Effect of supplementing Expt. 2

5 10 15 20 25 30

(“C)

0.33 12 10 16 0.77 0.58 0.36

(P < 0.05).

fatty acids) in the milk fat of individual cows sampled at three times during supplementation

low FFR

high FFR

33.7”’ 21.0” 12.3a 26.3” 29.4” 101.1” 14.0” 237.4” 19.6 11916 290.4” 18.3” 8.0”

28.7b 16.2b 8.9b 19.1b 2:.8b 85.2b 11.6b 198.1b 20.6 126.0 362.6b 19.98b 6.0b

19.8’ 10.5’ 5.5” 13.2’ 16.1’ 69.9’ 10.4b 180.8a 21.9 120.6 427.4’ 23.0” 4.9c

differ significantly

1.4 0.9 0.6 1.8 1.5 3.6 0.9 9.0 1.2 7.1 12.1 2.2 0.5

(P < 0.05).

cows at pasture with two levels of FFR on the solid fat content of the milk fat (g/kg

fat) at different temperatures

Treatment

SE of diff.’

control

low FFR

high FFR

536.0”+ 481.0” 401 .oa 257.0 131.0” 71.0a 27.0”

484.0b 428.0b 356.0b 240.0 135.0ab 76.0ab 32.0b

447.0’ 405.Ob 341.0b 242.0 151.0b 89.0b 39.0’

‘SE of diff. = standard error of difference. + Within rows, means not sharing a common superscript

with

SE of diff.’

control

‘SE of diff. = standard error of diffemece. +Within rows, means not sharing a common superscript

0

differ significantly

Treatment

c4: C6:O C8:O ClO:O c12:o c14:o C14:l C16:O C16:l C18:O Cl8:l C18:2 C18:3

Temperature

SE of diff.’

control

‘SE of diff. = standard error of difference. +Within rows, means not sharing a common superscript

at pasture in

differ significantly

(P < 0.05).

13.8 14.5 14.5 13.0 8.9 6.4 1.4

in

20

J.J. Murphy et al. /Livestock Production Science 44 (1995) 13-25

300-

(a) ma260-

240 -

220-

200-

180

-

160’

I

-12

I

,

I

I

-5

1

3

4

I

,

9

1

I

1

1

I

I

1

1623303744515665 oar

3m-

250’. -12

, , , , , , , , , , , , , -5

1

3

4

9

16

23

30

37

44

5,

56

65

centration was significantly increased (P < 0.05). The fatty acid composition of the milk fat produced by the control and FFR supplemented cows is shown in Table 7. Feeding both FFR supplements significantly reduced the proportions of C4:O (P < O.Ol), C14: 1 (P
z?Qo2m-

250,. -12

-5

, , , I,,

1

3

4

9

, , , , , , 16

oar

23

30

37

44

5,

56

65

Fig. 1. The (a) C16:0, (b) C18:l and (c) solid fat content of the milk fat at 10°C producedby cows on the control (O), 1.6 kg FFS (0). 3.2 kg FFS (A) and 3.2 kg SBM ( A ) in Expt. 1. Supplememtation commenced on day 0.

J.J. Murphy et al. /Livestock Production Science 44 (1995) 13-25

21

Table 9 The effect of milk yield, milk constituent yield and milk composition of feeding a FFR concentrate in Expt. 3 Treatment

Milk yield (kg/day) Fat yield (g/day) Protein yield (g/day) Lactose yield (g/day)

Fat (g/kg) Protein (g/kg) Lactose (g/kg)

SE of diff.’

control

FFR

21.2”+ 151 692 954” 36.1” 32.7 45.1

22.8” 726 723 1036b 31.9b 32.0 45.4

0.55 22 17 28 0.70 0.32 0.28

‘SE of diff. = standard error of difference. +Within rows, means not sharing a common superscript differ significantly (P < 0.05)

cantly increased (P < 0.01) and milk fat concentration was significantly reduced (P < 0.001) . Other parameters were not significantly affected. Neither calving to service interval (control 80 days, FFR 74 days), calving to conception interval (control 94 days, FFR 82 days), percent infertile (control 12, FFR 13)) services per conception for conceived cows (control 1.62, FFR 1.33) or services per conception for served cows (control 1.90, FFR 1.70) were significantly different between treatments. Four of the 14 blood metabolites measured were significantly different between treatments. Glucose (P < 0.05) and cholesterol (P < 0.001) concentrations were higher and serum glutamic pyruvic transaminase (SGPT) (P < 0.01) and serum glutamic oxaloacetic transaminase (SGOT) (P < 0.001) activities were lower in the FFR group compared to the control. Milk SCC levels were similar in both treatments. The fatty acid profiles and solid fat content of the milk fats on the different treatments were similar to those observed in Expt. 2. The Cl6:O and solid fat content at 10°C were consistently lower and the C18: 1 was consistently higher in the milk fat of the FFR group compared to the control.

4. Discussion 4.1. Fatty acid composition It has been shown that butter made from milk fat produced at pasture is softer than butter made from milk fat produced indoors (Cullinane et al., 1984) sug-

gesting differences in the fatty acid composition of the milk fats. However, there is limited data on the seasonal or lactational changes in the fatty acid composition of bovine milk fat. As lactation progresses the proportion of short to medium chain-length fatty acids increases and the proportion of C 18 fatty acids tends to decrease up to about mid-lactation, and little change takes place subsequently (Davies et al., 1983). Also, the proportion of Cl8 to Cl6 and Cl4 fatty acids increases with a changeover from a winter diet of hay and concentrates to a summer diet of pasture. This winter/summer trend is evident when the fatty acid composition of the milk fat on the control treatments indoors (Murphy et al., 1990, 1995) is compared with the fatty acid composition of the milk fat on the unsupplemented control treatments at pasture here. Indoors the proportions of C4-C14, C16, C18:l and total Cl8 fatty acids were 250-280,290-330, 180-240 and 290-370 g/kg fatty acids, respectively, whereas the corresponding values at pasture reported here were 220-230,230-240,280290 and 420440 g/kg fatty acids. The proportion of C18: 1 in the milk fat produced unsupplemented from pasture is almost as high as that in milk fat produced by cows indoors supplemented with about 700 g rape oil or maize oil in the form of FFR or maize distillers grains. The higher proportion of C 18: 1 in milk fat produced on pasture is probably because of the high intake of C 18 fatty acids from grass leading to a greater suply of C18:O to the mammary gland which is desaturated there to C18: 1. Grass contains between 10 and 30 g/ kg lipid with 900 g/kg of the fatty acids having 18carbon chain lengths.

J.J. Murphy et al. /Livestock

260

240

220

290

130

180 -10

0

10

20

30

40

50

80

0

10

20

30

.O

50

I 60

500-

460460440-

4204w-

380350340-

32a-

xm2m260-

240220. 200, -10

Day*

Production Science 44 (1995) 13-25

The fatty acid composition of the oil supplied by FFS and FFR is quite different. More than 850 g/kg of the fatty acids in both are 18 carbon fatty acids but soya oil has over 550 g/kg of its fatty acids as Cl82 with about 200 g/kg C18:l and 80 g/kg C18:3, whereas rape oil consists of over 500 g/kg C18:l with about 250 g/kg of C18:2 and 130 g/kg of C18:3. Supplementing cows with these two different oil sources at pasture, however, gave the same trend in changes in the fatty acid composition of milk. This arises because of the hydrogenation of unsaturated fatty acids in the rumen and subsequent desaturation of C18:O to C18:l in the mammary gland. This effect is evident in the results reported here where supplementing pasture with 1.6 and 3.2 kg of FFS increased the C18:l in milk fat by 200 g/kg and 230 g/kg and supplementing pasture with concentrates containing 0.83 and 1.6 kg of FFR increased the C 18:1 in milk fat by 250 and 470 g/kg, respectively. The greater response to FFR may be due to the direct absorption of some C18: 1 which escaped biohydrogenation in the rumen. It would appear that some of the unsaturated fatty acids escaped biohydrogenation in the rumen because both FFS and FFR supplementation increased the proportion of C18:2 in the milk fat. The proportional increases were greater with FFS (0.81 and 1.60) than FFR (0.09 and 0.26) probably because of the higher levels of Cl 8:2 in the former. The level of short to medium chain-length fatty acids (C6-Cl6) in milk fat decreased with FFS and FFR supplementation at pasture. Typically de-novo synthesis of fatty acids decreases with increased levels of supplementary fat (Grummer, 1991). It is not totally clear whether this occurs due to effects of the fat in the rumen or due to inhibition of fatty acid synthesis by long chain fatty acids in the mammary gland. Clapperton and Banks (1985) concluded that the majority of the inhibition was due to effects within the mammary gland. In terms of human nutrition and prevention of coronary heart diseases the changes in the milk fatty acid composition achieved here would be beneficial. The whole area of animal products in a healthy diet has been

Fig. 2. The (a) C16:0, (b) C18:1, and (c) solid fat content of the milk fat produced by cows on the control (0). low FFR ( l), and high FFR (A) treatments in Expt. 2. Supplementation commenced on day 0.

J.J. Murphy et al. /Livestock Production Science 44 (1995) 13-25

recently reviewed by Gibney (1993). It is now accepted that Cl80 does not raise blood cholesterol and that Cl 8: 1 lowers LDL cholesterol without affecting HDL cholesterol, which is positive, because HDL cholesterol is removed from the body. It appears that C12:O-C16:0 fatty acids are more hypercholesterolaemic than others. These recent findings should open up the debate on the relationship between milk fat and blood cholesterol levels because the C12-Cl6 fatty acids only account for 350-400 g/kg and Cl8 fatty acids account for 420-430 g/kg of fatty acids in the control milks in the present study. Supplementing with FFS and FFR reduced the Cl2416 fatty acids to less than 300 g/kg and increased the Cl8 fatty acids to over 550 g/kg. Also supplementation increased the level of C18:l from about 300 to over 400 g/kg fatty acids. Thus, these changes due to FFS and FFR supplementation further enhance the perception of milk fat, nutritionally. The changes in fatty acid composition due to supplementation were reflected in changes in the triglyceride composition of the milk fat. The changes observed here where pasture was supplemented with FFS were in general similar to those observed indoors where silage was the basal roughage (Murphy et al., 1990). In both studies supplementation with FFS significantly increased triglycerides with 40, 52 and 54 carbon atoms and significantly decreased those with 36,42,44,46 and 48 carbon atoms. 4.2. Fat sofmess As stated by Palmquist et al. (1993) C16:O and C 18: 1 are the major fatty acids which can be manipulated to influence the melting characteristics of milk fat. A higher ratio of C 18: 1 to C16:O gives a softer milk fat. The spreadability of butter at refrigeration temperatures is important in increasing its acceptability to the consumer. The solid fat content in the milk fat at different temperatures is a good indicator of its softness and most dairy spreads (mixtures of milk fat and vegetable fat) have a solid fat content at 10°C of 300-320 g/kg. In the present studies supplementing with the higher levels of FFS and FFR gave C18:l to C16:O ratios in the milk fat of 1.8-2.4 and solid fat at 10°C of 300-360 g/kg. The corresponding values in the unsupplemented control diets were 1.2-l .5 and 4W20 gl kg. This shows that supplementation with FFS and FFR

23

results in a softer milk fat from which a butter spreadable at refrigeration temperatures could be manufactured. It is also interesting that at 20°C the milk fats produced in this study with supplementation were similar or just marginally harder than the control milk fats which indicates that butter made from such milk fat would not have the soft oily texture observed with butters made from milk fat high in polyunsaturated fatty acids (Badings et al., 1976). 4.3. Cow pelformance The milk yield response by cows to supplementation at pasture depends on a range of factors including grass supply, grass quality, concentrate feeding level, concentrate type, stage of lactation, appetite capacity and dairy merit of the cows. Leaver et al. ( 1968) reported an average response of 0.33 kg milk per kg of concentrates; Joumet and Demarquilly (1979) reported a response of 0.40 kg milk per kg of concentrate and Stakelum et al. ( 1988) reviewing a number of experiments at these Research Centres reported responses ranging from 0.13-0.98 with a mean of 0.53 kg milk per kg of concentrate. The response to supplementation at pasture can only be assessed here in Expt. 1, because in Expt. 2 grass meal was also fed, and in Expt. 3 a portion of the experimental period was indoors. Feeding 1.6 kg of FFS gave a milk response of 0.38 kg per kg of supplement and feeding 3.2 kg of FFS or SBM gave responses of 0.16 and 0.31 kg milk per kg of supplement, respectively. Because of the high ME concentrations of FFS the energetic response observed here is quite low. This may be due to the oil intake from the FFS, having a negative effect on fibre digestion in the rumen. These responses are in general lower than those previously reported and should be treated cautiously as the increases in milk yield due to supplementation were not statistically significant. Supplementation with FFR, in Expt. 2, significantly increased protein yield and had no significant effect in the other two experiments. The significant reduction in milk fat concentration with FFR supplementation in Expts. 2 and 3 was probably a ‘dilution’ effect because milk yield was significantly increased. Also, fat yield was significantly increased by supplementation with the low FFR concentrate and unaffected in the other cases. No significant effect on fat concentration was observed with FFS supplementation but this was probably due to the absence of a

24

J.J. Murphy et al. /Livestock Production Science 44 (1995) 13-25

significant increase in yield, precluding a ‘dilution’ effect, rather than any specific effect of the different oilseeds.

5. Conclusions Overall, feeding supplements containing FFS or FFR to lactating cows on pasture did not reduce animal performance in terms of milk, fat, protein and lactose yield and did not apparently affect cow fertility or udder health. Supplementation with the oilseeds altered the fatty acid and triglyceride composition of the milk resulting in decreases in the short to medium chainlength fatty acids and increases in the Cl8 fatty acids particularly C18:l. These changes in fatty acid composition resulted in a softer milk fat from which a high monounsaturated fatty acid butter, spreadable at refrigeration temperatures, could be manufactured.

Acknowledgements The authors thank Mr. S. Aheme, Mr. Noel Byrne, Mr. Michael Dolan, Mr. D. Eason, Mr. P. Feeney and Mr. M. Nolan for technical help, Dr. D. Harrington for statistical analysis, and Irish dairy farmers and the European Community Co-Responsibility fund for partial financing of this project.

References Badings, H.T., Tamminga, S. and Schaap, J.E., 1976. Production of milk with a high content of polyunsaturated fatty acids. 2. Fatty acid composition of milk in relation to the quality of pasteurized milk, butter and cheese. Neth. Milk Dairy J., 30: 118-131. Banks, W., 1987. Opportunities for varying the composition of cows’ milk. J. Sot. Dairy Technol., 40: 96-99. Clapperton, J.L. add Banks, W., 1985. Factors affecting the yield of milk and its constituents, particularly fatty acids, when dairy cows consume diets containing added fat. J. Sci. Fd. Agric., 36: 1205-1211. Cullinane, N., Condon, D., Eason, D., Phelan, J.A. and Connolly, J.F., 1984. Influence of season and processing parameters on the

physical properties of Irish butter. Ir. J. Fd. Sci. Technol., 8: 1325. Davies, D.T., Holt, C. and Christie, W.W., 1983. The composition of milk. In: Mepham, T.B. (Ed.), Biochemistry of Lactation. Elsevier, Amsterdam, pp. 71-117. De Peters, E.J., Taylor, S.J., Franke, A.A. and Aguirre, A., 1985. Effects of feeding whole cottonseed on composition of milk. J. Dairy Sci., 68: 897-902. Emanuelson, M., 1989. Rapeseed products of double low cultivars to dairy cows. Effects of long term feeding and studies on rumen metabolism. Report 189. Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Uppsala. Gibney, M.J., 1993. Animal products in a healthy diet. In: Farrell, D.J. (Ed.), Recent Advances in Animal Nutrition in Australia. Department of Biochemistry, Microbiology and Nutrition, University of New England, pp. 145-152. Grummer, R.R., 1991. Effect of feed on the composition of milk fat. J. Dairy Sci., 74: 3244-3257. Handy, K.W. and Kennelly, J.J., 1983. Influence of feeding whole canola seed, ground canola seed and a protected lipid supplement on milk yield and composition. Agriculture and Forestry Bulletin of the University of Alberta Special Issue, pp. 83-86. Joumet, M. and Demaquilly, C., 1979. Grazing. In: Broster, W.H. and Swan, H. (Eds.), Feeding Strategies for High Yielding Dairy Cows. Granada Publishing, London, pp. 295-321. Leaver, J.D., Campling, R.C. and Holmes, W., 1968. Use of supplementary feeds for grazing dairy cattle. Dairy Sci. Abstr., 30: 355361. Mattson, F.H. and Gmndy, S.M., 1985. A comparison of effects of dietary saturated, monounsatumted and polyunsaturated fatty acids on plasma lipids and lipoproteins in man. J. Lipid Res., 26: 194-202. McGuffey, R.K. and Schingoethe, D.J., 1982.Whole sunflower seeds for high producing dairy cows. J. Dairy Sci., 65: 1479-1483. Murphy, J.J., Connolly, J.F. and McNeill, G.P., 1995. Effects on milk fat composition and cow performance of feeding concentrates containing full fat rapeseed and maize distillers grains on grass-silage based diets. Livest. Prod. Sci., 44: l-l 1. Murphy, J.J., McNeill, G.P., Connolly, J.F. and Gleeson, P.A., 1990. Effect on cow performance and milk fat composition of including full fat soyabeans and rapeseeds in the concentrate mixture for lactating dairy cows. J. Dairy Res., 57: 295-306. Palmquist, D.L., Beaulieu, D.A. and Barbano, D.M., 1993. Feed and animal factors influencing milk fat composition. J. Dairy Sci., 76: 1753-1771. Perry, F.G. and McLeod, G.K., 1968.Effects of feeding raw soybeans on rumen metabolism and milk composition of dairy cows. J. Dairy Sci., 51: 1233-1238. Stakelum, G., Dillon, P. and Murphy, J.J., 1988. Supplementary feeding of grazing dairy cows. In: O’FarreIl, K. (Ed.), Moorepark Dairy Farmers’ Conference, Teagasc, Ireland, pp. 25-27.

J.J. Murphy et al. /Livestock

Production Science 44 (1995) 13-25

25

R&urn6 Murphy, J.J., Connolly, J.F. et McNeill, G.P., Effets de IImentation de graines de sojaet de colza entieres sur les performances de vaches latietes au plturage. Lioest.Prod. Sci., 44: 13-25.

et le taux butyreux

Trois essais ont Bte emtrepis pour ttudier les effets de I’ahmentation de graines de soja (FFS) et de colza (FFR) non d&lipid& sur les performances et la composition du lait de vaches latieres au plturage. Darts l’essai 1 quatre lots de 15 vaches tous au pfiturage ont 6tb mis chacun sur les regimes de compldmentation suivants, ( 1) aucune complementation (temoin), (2) 1,6 kg/vache/jour de FFS ( 1.6FFS). (3) 3,2 kg/ vache/jour de FFS (3,2 FFS ), et (4) 3,2 kg/vache/jour de tourteau de soja SBM (3.2 SBM), pendant 11 semaines. Ni la producion laitiete, ni la composition du lait ou la quantitt de constituants secretes ont signiticativement differes entre traitements. La composition en acides gras et la teneur en matieres grasses du lait ont ete les m&nes avec le temoin et avec le lot 3.2 SBM. Cependant les deux niveaux de FFS ont signilicativement mduit les proportions de C6:O (PC O,Ol), CS:O, ClO:O, C12:0, C14:0, C14:l et C16:l (P
Kurzfassung Murphy, J.J., Connolly, J.F. und McNeill, G.P., 1995. EinBuO der Filtterung von Konzentraten mit Raps-und Sojabohnenschrot und Milchzusammensetzung von Milchkilhen auf der WEide. Liuest. Prod. Sci., 44: 13-25.

auf die Leistung

Es wurden drei Experimente durchgeftihrt, urn den EinfluS der Filtterung von Sojabohnenschrot (nicht extrahiert, FFS) und Rapsschrot (nicht extrahiert, FFR) auf die Milchfettzusammensetzung lund die Milchleistung von K&n zu untersuchen. Im ersten Experiment wurden 4 Gruppen von je 15 Kilhen auf der Weide folgenden Behandlungen unterzogen, in denen dem Krafifutter 1. nichts ( Kontrolle),2. 1.6 kg FFS ( 1,6 FFS) , 3. 3,2 kg FFS (3.2 FFS) und 3,,2 kg Sojabohnemnehl (3.2 SBM) zugesetzt und 11 Tage lang verabreicht wurde. Die Milchleistung, die Leistungen an Milchinhaltstoffen und die Milchzusammensetzung wurden zwischen den verschiedenen Behandlungen nicht signifikant beeinflu8t. Die Fettsiiurenzusammensetzung und der Gehalt an festen Fetten in der Milch waren bei der Kontrolle und 3,2 SBM Lhnlich. Jedoch senkte dieFiJtterungvon Rapsschrot aufbeiden Niveaustufen die Anteile von C6:O (P< 0.01). C8:0, ClO:O, C12:0, C14:0, C14: 1 undC16: 1 (P < 0,001) und erhohte den Anteil von C18:0, Cl&l, C18:2 (P