Farm systems research at Ruakura – a 60-year legacy underpinning profitable and sustainable pasture-based dairy systems

Figures & data

Table 1. Timing and brief description of, and references for major farm systems experiments at No. 2 Dairy between 1944 and 2004.

Period	Experiment #	Type of Experiment^a	Theme	Experiment name	References
1944–1957	1	F	1 & 3	Nutrition - Lifetime project	McMeekan and Walshe (1963)
1945–1957	2	F	1	Effects of grazing method – ‘controlled versus uncontrolled’ grazing	McMeekan (1947, 1954, 1956, 1960)
1957–1961	3	F	1	Interaction of grazing method and stocking rate	McMeekan and Walshe (1963)
1958–1961	4	C	1	Grazed pasture parameters	Campbell (1966a, 1966b, 1966c)
1961–1965	5	F	7	Genetic quality, stocking rate and pasture management	Carter (1964)
1965–1966	6	F	2	Redistribution of available feed	Campbell and Clayton (1966)
1966–1967	7	F	6	Meal feeding of dairy cows	Annual report (1966–67)
1967–1968	8	F	6	Feeding and management of dairy cows	Annual report (1967–68)
1968–1974	9	F	8	Integration of dairying and beef raising	Campbell et al. (1974)
1972–1976	10	F	7	Comparison of Jersey and Friesian-Jersey crossbreds	Campbell (1977)
1977–1979	11	F	6	Pasture and maize rotation in dairying	Campbell et al. (1978)
1979–1982	12	F	10	Effects on production of milksolids of using nitrogen to increase pasture growth	Bryant et al. (1981), Bryant (1983)
1982–1986	13	F	2	Autumn-winter management and dairy production	Bryant (1984, 1990), Bryant and L'Huillier (1986)
1986	14	C	7	Comparative performance of Jersey and Friesians in mid-lactation	L’Huiller et al. (1988)
1986–1987	15	C	2	Management of the dairy herd during a dry summer	Bryant and Macdonald (1987)
1986–1987	16	C^1	11	The effect of bovine somatotropin in a sustained release preparation (Somidobove) on milk production of cows at pasture in New Zealand	Davis et al. (1999)
1986–1988	17	F	4	New ryegrasses and Matua Prairie grass	Thom et al. (1990, 1992)
1989–1990	18	F	2	Early spring management	Bryant (1990)
1990–1993	19	F	7	Friesian vs Jersey comparison	Ahlborn and Bryant (1992), Penno (1998), Spaans et al. (2018)
1991–1993	20	F	4	Pasture cultivar comparison	Thom and Prestidge (1996), Thom and Bryant (1996)
1993–1998	21	F	6 & 10	1.75 t MS/ha	Penno et al. (1996); Macdonald (1999); Macdonald et al. (2017)
1996–1997	22	C	6	Balancing pasture and maize silage diets for dairy cows using urea, soybean meal or fishmeal	Macdonald et al. (1998)
1997–1998	23	C	2	Mowing pasture to improve milk production	Kolver et al. (1999)
1998–2001	24	F	5 & 11	Whole farm efficiency experiment	Macdonald et al. (2001, 2008a, 2010, 2011), Roche et al. (2016)
1998–2001	25	F	9	Effects of time on calving on dairy production	Auldist et al. (2002), Spaans et al. (2019)
2001–2004	26	F	7	Holstein-Friesian Strain experiment	Macdonald et al. (2005, 2007, 2008b), Lucy et al. (2009)

^a Signifies type of experiment. F = Farmlet, C = Component, C¹ = Component imposed on a Farmlet experiment.

Table 2. Summary results from a series of experiments investigating the effect of grazing strategy (Rotational Grazing: RG; Set Stocking: SS) on milk and pasture production, and how these effects were modified by interacting system-level factors: stocking rate (SR) and cow genetic merit (GM)^a.

Experiment^b	Comparison	Year		Grazing management		Stocking rate		Genetic merit			Main effects P-value			Interaction P-value
				RG	SS	Low	High	High	Low	SED^c	MGT	SR	GM	MGT-SR	MGT-GM	SR-GM	MGT-SR-GM
1	Grazing strategy	1948–1957	FCM^c, kg/cow
			Fat, kg/cow	160.0	141.4					2.30	<0.001
2	Grazing strategy × SR	1957–1961	FCM^c, kg/cow	4085	3728	4142	3671			84.2	<0.01	<0.001		0.07
			Fat, kg/cow	186.4	169.4	188.6	167.2			3.96	<0.01	<0.001		<0.05
			Fat, kg/ha	494	449	443	493
			Lwt^c, kg	366	380	376	371			3.6	<0.01	0.22		0.17
			Pasture, kg/ha	12,738	11,124	11,637	12,226			1358	0.28	0.68		0.87
3	Grazing strategy × SR × GM	1961–1965	FCM^c, kg/cow
				173.4	150.6	167.5	156.5	175.4	148.6	2.08	<0.001	<0.001	<0.001	<0.01	0.2	0.79	0.38
			Fat, kg/ha	460	399	394	462

^a LSR – Low stocking rate = 2.35 cows/ha; HSR – High Stocking rate = 2.95 cows/ha; HGM – High Genetic merit; LGM – Low Genetic merit;

^b Experiment 1 compared the two grazing management strategies (RG versus SS) over a 12-year period. Experiment 2 compared cows in either RG or SS at 2 stocking rates (Low = 2.35 & High = 2.95 cows/ha). Exp 3 again compared grazing management & SR and included cows of High Genetic Merit, from the Ruakura herd or Low Genetic Merit cows sourced from commercial farms.

^c SED = Standard Error of the Difference; FCM = fat corrected milk; Lwt = cow live weight.

Figure 1. Daily pasture growth rate (vertical bars; kg DM/ha/d) and per ha DMI of dairy cows at 2 stocking rates, 2.2 (

), and 4.3 (

) cows/ha. PSC = Planned start of calving, PSM = planned start of mating.

Table 3. No. 2 dairy experiment design for 1982/83 & 1983/84 for autumn-winter (April to July), (Experiment 13, Phase 1: Adapted from Bryant and L'Huillier 1986).

	Nominal rotation* (days)		Actual average rotation (days)
Farmlet	April–May	June–July	April–July	Aug–Nov
1	128	96	99	27
2		64	84	26
3	96	96	84	26
4		64	72	25
5	64	96	67	24
6		64	55	25
7	32	96	60	24
8		64	46	25

*A rotation of 100 days means that 1/100th of the farm was grazed each day.

Table 4. Experimental design at No. 2 dairy for 1984/85 and 1985/86. (Experiment 13, Phase 2: adapted from Bryant and L'Huillier 1986).

	Nominal rotation* (days)		Actual average rotation (days)
Farmlet	April–July	August–November	April–July	August–November
1	128	16	107	23
2		32	107	36
3	96	16	77	22
4		32	77	34
5		8	77	11
6	32/64	16	46	21
7		32	46	34
8		8	46	11

*A rotation of 100 days means that 1/100th of the farm was grazed each day.

Table 5. Effect of differing rotation lengths on farm cover (kg DM/ha) and subsequent milksolids production (Experiment 18; 1989/90).

Treatment	1	2	3	4
Period	*Rotation length (Days)
21/7 – 3/8	100	58	41	33
4/8 – 17/8	60	37	26	20
18/8 – 31/8	52	35	21	14
1/9 – 14/9	42	28	14	7
No. of rotations (21/7 – 14/9, 56 days)	1.0	1.5	2.5	4.1
Farm cover at 18 July kg DM/ha	2000	1900	1900	1900
Farm cover at 22 Sept kg DM/ha	1600	1500	1200	1100
MS/cow to 1 October	78	88	83	81
MS/cow to 9 February	248	267	257	246

*A rotation of 100 days means that 1/100th of the farm was grazed each day.

Figure 2. Relationship between proportion of farm grazed during April, May and June, and the amount of pasture on the farm in July (Experiment 13, Phase 1).

Note: A rotation of 100 days means that 1/100th of the farm was grazed each day.

Figure 3. The effect of rotation length in a winter-spring feed deficit on the long-term pasture cover (i.e. feed availability; Experiment 13 Phase 2). Treatments were: a slow rotation prior to calving and post-planned start of calving (

), a fast rotation prior to calving and slow post-calving (

), fast rotation prior to calving and post-calving (

).

Figure 4. The spring rotation planner dictates how much area should be allocated each day from calving to 'balance day' (i.e., when pasture growth is equal to herd demand). The farmer must ration this area between dry and lactating cows. The area allocated increases with time, matching the increasing number of cows calved and the greater dry matter intake of lactating cows (Developed from Experiment 13 & 15). The provided example is a 100 ha farm with a planned start of calving in early July. Rotation length (

), Area grazed/day (

).

Figure 5. The autumn rotation planner developed from autumn-winter grazing management experiment that dictates how much area can be allocated each day. This area is rationed between dry and lactating cows to ensure dry cows are allocated enough for condition score gain, while the milkers are allocated enough for maintenance and milk production. The provided example is for a 100 ha farm, with a planned start of calving (PSC) in early July. Rotation length (

), Area grazed/day (

).

Figure 6. Live weight gain profile of animals from weaning (9 weeks) until post-calving in their third lactation: A =

Rotational grazing or =

Set-stocking up to pre-calving and then rotational grazing as lactating cows; B =

Rotational grazing or =

Set-stocking up to pre-calving and then set-stocked grazing as lactating cows (Experiment 1).

Table 6. Effects of grazing management strategy^a as replacement heifers (pre-calving) and during lactation (Lactating) on annual milk fat yield/cow (kg; estimated^b MS (fat and protein) yields in parentheses).

	Lactating		SED	P-value
Pre-calving	Rotational Grazing	Set-Stocking		Pre-calving	Lactating	Pre-calving × Lactating
Rotational grazing	160.0 (280)	141.3 (280)	3.25	0.97	<0.001	0.99
Set-Stocking	160.1 (247)	141.4 (247)

^a Grazing management strategies were either Rotational Grazing (i.e. Controlled) or Set-Stocking (i.e. uncontrolled), either as young stock (pre-calving) or post-calving (i.e. lactating cows).

^b Estimated milk fat and protein yields = milk fat yield × 1.75.

Figure 7. Live weight targets for Jersey calves from 9 wks of age until pre-calving at 24 mo (i.e. the ‘Plunket graph’; Adapted from McMeekan 1954). The middle line depicts the desired growth rate with the bottom being below the target and the top line being above the target.

Figure 8. Average annual pasture growth (t DM/ha/yr; ) for No 2 Dairy over 5 yr periods (estimated for 1960s & 1970s using 15.0 kg DM/kg MS; from 1979 growth calculated from weekly farm walks).

Table 7. Summary of Whole Farm Efficiency experiment: experimental design, and summary pasture growth, and production results (Experiment 24).

	Stocking rate					P-value
	2.2	2.7	3.1	3.7	4.3	Linear	Quadratic
Planned CSR^a kg Lwt/t DM	62	76	90	103	120
Actual CSR	60	70	76	89	91
Pasture grown kg DM/ha/yr	18,048	18,050	19,484	18,538	20,394	0.11	0.74
Days in milk	291	274	258	234	221	<0.001	0.74
Milksolids kg/cow	407	365	338	295	265	<0.01	0.01
Milksolids kg/ha	895	972	1047	1092	1141	<0.01	<0.01

^a CSR-Comparative stocking rate (kg Lwt/t/DM/ha).

Figure 9. The effect of stocking rate (cows/ha) on pasture harvest (t DM/ha;

) and estimated (est.) methane (CH₄) emissions/ha (kg CO₂-eq;

), milksolids production/ha (kg;

) and operating profit/ha (NZ$;

), and nitrate leached/ha (kg;

). Methane emissions/ha were estimated from the equation: kg DM × 21.6 (Clark 2008, Macdonald et al. 2008b, 2011. Roche et al. 2016).

Table 8. Treatment details for 1.75 t MS/ha experiment (Experiment 21; Phase 1; 1993–1995 adapted from Penno et al. 1996).

Farmlet	1	2	3	4	5	6	7
Cows/ha	3.24	3.24	3.24	3.24	4.48	4.48	4.48
Number of cows	21	21	21	21	29	29	29
N kg/h/yr (nominal)	0	0	200	400	0	200	400
N kg/h/yr (applied)	0	0	215	380	0	206	370
Maize grain supplement	No	Yes	Yes	Yes	Yes	Yes	Yes
Maize grain offered (kg DM/c/yr)^a		548	139	105	1460	1043	958

^a Average of 2 years.

Table 9. Experimental design, and summary production and economic results (for the 1.75 t MS/ha experiment ( Least square means over 3 years: 1995/96–1997/98). Effects of nitrogen fertiliser use, stocking rate, and supplementary feeding on modelled per ha greenhouse gas (GHG) emissions are presented (Experiment 21; Phase 2; adapted from Macdonald 1999 & Macdonald et al. 2017).

Herd	1	2	3	4	5	6	7	8
Treatment	LSR^a 0N^c	LSR 200N	LSR 400N	HSR^b 200N	HSR 400N	HSR 200N MG^d	HSR 200N MS^e	HSR 200N BR^f
Stocking rate (cows/ha)	3.4	3.4	3.4	4.4	4.4	4.4	4.4	4.4
Nitrogen used (Kg N/ha)	0	202	418	203	416	207	209	211
Milksolids (Kg/cow)	311	357	390	267	296	396	359	400
Milksolids (Kg/ha)	1042	1196	1306	1177	1305	1746	1574	1764
Total GHG –(kg CO2 eq/ha)	11,779	15,431	17,753	16,758	19,080	22,590	19,928	22,823
Operating profit^g ($/ha)	$3138	$3722	$4112	$3004	$3572	$3116	$3369	$1650^h

^a LSR-Low stocking rate = 3.3 cows/ha.

^b HSR-High stocking rate = 4.4 cows/ha.

^c N-Nitrogen.

^d MG-Maize grain-1.25 t DM/c/yr.

^e MS-Maize silage-1.28 t DM/c/yr.

^f BR-Balance ration-1.46 t DM/c/yr.

^g Operating profit calculated as outlined in Macdonald et al. (2017), but with a MS price of $6.50/kg MS. All expenses remained the same.

^h Operating profit estimated from Macdonald et al. (2017), with the assumption that the balanced ration supplement cost $750/t and the MS price was $6.50.

Table 10. The effects of grazing strategy (Controlled vs Uncontrolled), Stocking rate (Low: 2.35 cows/ha vs High: 2.95 cows/ha), and cow genetic merit (HGM vs LGM) on milk fat production/cow and per ha and the % increase in milk production from genetic merit, stocking rate, and grazing strategy (Experiment 5).

	CL	CH	UL	UH
Per cow
HGM	189	184	170	149
LGM	162	155	148	127
Difference	26	29	21	22
Per ha
HGM	443	543	398	440
LGM	381	457	348	375
Difference	62	86	50	64
%increase/ha
GM	16%	19%	14%	17%
SR		39%		39%
Grazing strategy			23%	33%

Table 11. Principal results summarising the effects of stocking rate and breed on pasture and animal production variables and economic outcomes (Experiment 19; from Spaans et al. 2018).

Breed	Jersey		Holstein-Friesian			P-value
Stocking Rate	CSR80	CSR100	CSR80	CSR100	SED	Breed	CSR	Breed × CSR
Pasture production, kg DM/ha	17,267	16,214	16,273	13,424	533.9	<0.01	<0.01	0.05
Lactation length, d	262	223	261	226	3.3	0.64	<0.001	0.38
Pasture disappearance, kg/cow/yr	4340	3590	4856	3541	88.8	<0.01	<0.001	<0.01
Supplementary feed, kg/cow/yr	154	159	160	167	7.5	0.24	0.3	0.88
DMI, kg/cow/yr	4494	3749	5016	3708	87.9	<0.01	<0.001	<0.01
4% FCM, kg/cow/yr	4265	3520	5000	3635	69.1	<0.001	<0.001	<0.001
Fat, kg/cow/yr	198	163	211	153	3.2	0.6	<0.001	<0.01
Protein, kg/cow/yr	136	108	161	115	2.7	<0.001	<0.001	<0.01
Lwt post-calving, kg	364	356	450	416	5.8	<0.001	<0.001	<0.05
BCS at calving, 1–10 scale	4.9	4.8	4.9	4.6	0.06	0.16	<0.05	0.17
Calf birth weight, kg	25	26	36	36	1.2	<0.001	0.95	0.72
Total ME/cow, MJ	42,636	37,530	49,308	40,946	413.4	<0.001	<0.001	<0.01
Total ME/ha, MJ	152,230	168,884	147,923	163,783	1834.40	<0.01	<0.001	0.77
DIM to first heat	28	28	38	56	4.4	<0.001	<0.05	<0.05
Non-cyclers^3 (%)	3	1	18	13	2.8	<0.001	0.11	0.35
Submission rate^4 (%)	97	96	98	89	3.5	0.25	0.07	0.15
Conception (%)	60	62	68	64	5	0.21	0.72	0.43
Services/conception	1.6	1.6	1.5	1.5	0.12	0.36	0.94	0.88
AI pregnancy rate	74	78	85	75	6.3	0.46	0.5	0.18
In Calf (%)	91	94	98	91	4.3	0.5	0.5	0.14
Milk price	$5.88	$5.85	$5.97	$5.96
Gross Farm Revenue	7522	7767	7216	7005
Total Dairy Operating Expenses	4186	4891	3710	4515
Dairy Operating Profit	3336	2876	3505	2490
Expenses – cost/kg fat and protein	3.51	3.97	3.29	4.24

Table 12. Summary data for the three strains of Holstein-Friesian from birth to end of second lactation (Experiment 26).

	NZ70	NZ90	NA90	P-value
Age at puberty, d	329	356	373	<0.05
Lwt – 6 month, kg	153	162	169	<0.05
Lwt – 12 month, kg	239	248	258	<0.05
Lwt – puberty, kg	230	253	274	<0.05
Lwt – 24 month, kg	481	491	515	<0.05
Total feed allowance, t DM/cow	6.0	6.0	6.0
Stocking rate, cows/ha	3.1	3.1	3.1
CSR, kg Lwt/t DM	86	83	85
Milk, kg/cow	4811	5593	5479	<0.001
Milk fat, kg/cow	218	264	228	<0.001
Milk protein, kg/cow	162	204	187	<0.001
Milksolids, kg/cow	380	468	415
Efficiency, kgmilksolids/kg Lwt^0.75	4.24	4.39	3.93	<0.001
Postpartum anoestrous interval, d	32.2	38.7	28.4	<0.001
Conception to first AI, %	45	46	39	NS
Conception to second AI, %	54	48	44	NS
Interval 1st to 2nd AI, d	23.7	22.8	26.2	<0.05
Pregnant in 6 wk, %	70	69	54	<0.001
Pregnant in 8 wk, %	80	75	62	<0.001
Mean final Pregnancy rate, %	93	93	87	<0.05
Yr 3 calving date	Jul-30	Jul-28	Aug-07	<0.05

Notes: Milk production and reproduction data are presented from herds receiving 5.5 t DM pasture and 0.5 t DM supplementary feed per cow (i.e. total feed allowance of 6 t DM/cow) (adapted from Macdonald et al. 2007, 2008a).

Figure 10. Body condition score for the three strains of Holstein-Friesians over consecutive lactations that were evaluated at a range of feeding allowances in Experiment 26: 'The Dexcel Strain Trial'. (

NZ70 = a 1970s high Breeding Worth strain of New Zealand Friesian,

NZ90 = a 1990s high Breeding Worth Holstein-Friesian of New Zealand origin,

NA90 = a 1990s high Breeding Worth Holstein-Friesian of North American origin).

Table 13. Lactation lengths, yields of milk, milk fat and protein, and operating profit for herds of cows calving in July, October, January and April (Experiment 25; adapted from Spaans et al. 2019).

Planned start of calving	July	October	January	April	SED	P
Annual pasture intake, kg DM/cow	4073	4306	4679	4205	256.6	0.28
Annual DMI, kg DM/cow	4772	4677	5026	4905	160.4	0.32
Lactation length (d)	261	262	292	287	12.3	0.17
Milk kg/cow	4018	3681	3726	3843	188.2	0.07
4% Fat corrected milk, kg/cow	4057	4236	4878	4002	218.9	0.08
Milkfat (kg/cow)	184	169	171	180	8.3	0.08
Protein (kg/cow)	136	123	128	134	6.5	0.06
Milksolids (kg/cow)	320	292	299	314	14.8	0.07
Operating Profit ($/ha)	3137	2199	2455	2850

Figure 11. Daily rate of change in BCS in pasture-based cows. Profile derived from the average BCS profile of 1172 cows across 3209 lactations at No. 2 Dairy between 1986 and 2004. Source: Roche et al. (2007a).

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