An Evaluation of Over-Wintering Feeding Strategies Prior to Finishing at Pasture for Cull Dairy Cows

Transcription

1 Moorepark Dairy Research An Evaluation of OverWintering Feeding Strategies Prior to Finishing at Pasture for Cull Dairy Cows W.Minchin 1,2, F.Buckley 1, D.A.Kenny 2, F.J.Monahan 2, L.Shalloo 1 and M.O Donovan 1 1 Teagasc, Moorepark Dairy Research Centre, Fermoy, Co. Cork. 2 School of Agriculture, Food Science & Veterinary Medicine,UCD

2 An experiment was conducted to evaluate four experimental treatments for cull dairy cows. Fiftysix spring calving HolsteinFriesian nonpregnant cull dairy cows were randomly assigned to a four treatment experiment. The experiment was split into two periods; wintering period, OWP and spring finishing period, PII. The treatments were; the control (C) treatment, slaughtered on day 1; 75% grass silage and 25% straw (GS+SW); ad libitum grass silage (GS); and grass silage plus 6 kg concentrate DM/cow/day and milked twice daily (MGS+6C). Subsequently, cows were assembled as one herd and offered adlibitum herbage on a daily basis (SFP). All cows were finished to predefined carcass specification: carcass weight > 272 kgs, fat score 3 and carcass class P+ or O. Individual DM intake, live weight, body condition score, carcass classification and grazing management were measured. Total feed utilized DM was 2.0, 1.9 and 2.5 tonnes/cow for the GS+SW, GS and MGS+6C treatments, respectively. Cows on the GS treatment (115 days) finished on average 115, 33 and 38 days earlier than those on the C, GS+SW and MGS+6C treatments. Achieving finishing criteria, irrespective of diet will result in no difference in carcass characteristics however; ADG and days to slaughter are affected by overwintering strategies and finished at pasture.

3 Background Increased numbers (23% of dairy cow population) of cows are being presented for slaughter each year decline in fertility (Evans, 2004) Previous finishing trial based on grass silage and concentrate resulted in 50% of production costs associated with feed Grazed grass attractive due to its high feed quality and low cost

4 Background Little research for finishing cull cows at pasture, which is most relevant to profit for commercial farmers Previous cull cow finishing at spring/summer pasture high ADG, improved carcase characteristics and favourable financial returns 70 day finishing period (Walsh, 1986)

5 Objective To compare the live and carcass performance of cull dairy cows subjected to three overwintering strategies prior to finishing at pasture

6 Materials and Methods Four treatment study (n = 14) with a randomised block design Cows were blocked by liveweight, age, lactation number, body condition score and Holstein % 18% of the herd were primiparous cows.

7 Experimental treatments Over wintering period (OWP) Control group slaughtered on day 0 (C) 75 % grass silage and 25% straw (GS+SW) 100 % grass silage (GS) Milking treatment offered grass silage plus 6 kg conc. DM/cow/day (EXTLAC) Spring finishing period (SFP) Turnout to pasture until finish

8 Finishing criteria Targets Liveweight BCS Carcass weight Carcass Grade Fat Score 620kgs > 272 P+ O 3 4L

9 Days to slaughter 157 GS P+2= CW EXTLAC P+4 CW GS+SW P+3= CW

10 Trial Measurements (OWP) Liveweight Body condition score Skeletal measurements Back fat measure Group DM intake Milk production Individual DMI (week 7 using nalkanen technique)

11 Treatment performance Treatment GS+SW GS EXTLAC Sed Sig (OWP) Initial Liveweight (kg) NS End Liveweight (kg) 653 a 674 a 619 b ** Initial BCS NS End BCS 3.13 a 3.41 b 2.98 a 0.01 ** ADG (kg) 0.53 a 0.89 b 0.03 c 0.11

12 Milk production Treatment Milk Yield (kg/day) EXTLAC 16.4 s.d 3.51 Milk fat content (g/kg) Milk protein content (g/kg) Milk lactose content (g/kg)

13 Mean Group DM intake (OWP) Conc. Straw Silage kg/dm Treatment GS+SW GS EXTLAC

14 Trial Measurements (SFP) Liveweight Body condition score Skeletal measurements Back fat measure Individual DMI (week 15) Grass measurements (Pre/post heights, grass allowance, etc)

15 Grazing Management Pregrazing sward height 14.3 cm (s.d. 5.54) Postgrazing sward height 5.2 cm (s.d. 1.26) Daily herbage allowance Daily herbage mass Sward Utilization 15.2 kg DM/cow (s.d. 5.31) 2812 kg DM/ha (s.d ) 0.91 (s.d. 0.15)

16 Treatment performance Treatment C GS+SW GS EXTLAC Sed Sig NS NS Days on trial 64ab 34a 73b 7.24 * ADG (kg) 0.96a 0.62b 0.91a 0.16 * SFP End Liveweight (kg) BCS ADG Total experimental period Initial Liveweight (kg) NS End Liveweight (kg) 599a 714b 695b 685b Slaughter BCS 2.79a 3.52b 3.59c 3.50b a 0.81a 0.44b 0.15 * 0a 148b 115c 153b 8.55 ADG (kg) Days to slaughter

17 Daily DM intake (SFP) 16 Herbage intake 15 kg/dm GS EXTLAC GS+SW Treatment

18 Ingredient Composition (g/kg) Dry Matter DMD Silage Straw 912 Conc. 917 Grass ph 4.2 Crude protein NDF UFL OMD

19 Total feed budget Treatment (kg GS+SW GS EXTLAC Sed Sig DM/cow) OWP Feed utilized SFP Herbage utilized Total OWP+ SFP Feed utilized Total UFL Intake 1984a 1455b 2400c 15.9

20 Factory Measurements Kidney Channel Fat Weighed in factory on day of slaughter Carcass Grade and fat score achieved on day of slaughter at mechanical grading machine Each carcass boned out 48 hrs post slaughter individual cuts weighed Ultimate carcass ph

21 Boning cuts Fillet Knuckle Topside Strip loin

22 Boning data Treatment C GS+SW GS EXTLAC Sed Sig 64.2a 84.4b 84.3b 82.1b NS Bones NS Lean trim 4.0a 9.2b 8.3c 8.5c a 0.75b 0.75b 0.75b 0.01 Silverside full 6.5a 9.2b 9.3b 8.9b 0.25 Topside 7.9a 9.8b 9.8b 9.5b 0.28 Knuckle 5.0a 5.7b 5.7b 5.6b 0.19 Rump 4.9a 6.1b 6.2b 6.0b 0.22 Fillet 2.3a 2.8b 2.8b 2.7b 0.09 Strip loin 4.1a 6.4bc 6.6b 6.1c 0.22 Flank steak 0.5a 1.0b 0.9c 0.9bc 0.06 Cuts (kg) Total Hind Fat trim Saleable meat %

23 Summary Over winter feed restriction and milk production created prolonged finishing periods by 35 days Grass silage: the most efficient in terms of physical performance Significant differences in finishing feed budget Over winter feed restriction encouraged high pasture intake capacity and compensatory growth during SFP 36% improvement in carcass saleable meat for offering finishing diet Pasture based finishing strategies are attractive (high ADG) in a high feed price scenario

24 Questions?

25 Meat Measurements Sample of each carcass taken (800g) on day of boning, vacuum packed and stored at 20 C. Muscle colour Fat colour Protein content Fat content Moisture and Ash Tenderness

26 Meat quality analysis results Measurement C GS+SW GS EXTLAC Sed Sig Protein % NS Moisture % NS Ash % NS Fat % 2.1a 3.4b 3.6b 3.6b 0.30 Shear force (N/cm2) NS (L) NS (a) 11.7a 13.6b 14.2b 14.3b 0.50 (L) NS (b) NS Muscle Colour Fat Colour

27 Table 1. Fixed parameters (OWP) Variables Silage ( /t DM) 130 Concentrate ( /t DM) 280 Straw ( /kg DM) 94 Housing ( /wk) 1.4 Purchase price ( /kg) Labour ( /wk) Labour Milking ( /wk) 7.34 Milking facilities ( /wk) 1.92

28 Table 1. Fixed parameters (SFP) Variables Grass ( /kg DM) 70 Sell price ( /kg) 2.42 Labour ( /wk) Sell price ( /kg) Med vet and other Mortality (%) 2 Interest (%) 8

29 Table 1. Medium buying and selling price 2 milk prices ( 06 and 07) Purchase Price /cow Selling Price /cow Housing Cost /wk Margin /cow C GS+SW GS EXTLAC 308 (M) (1.26) 778 (M) (2.42) (Dec 07) 308 (M) (1.26) 778 (M) (2.42) (Nov 06) (L) (L)