The effect of body condition score change 15 days prior to calving on lactation curve and production parameters in grazing dairy cows in Ireland M.R. Sheehy* 1,2, F.J. Mulligan 1, M.A. Crowe 1, S.P.M. Aungier 1, and A.G. Fahey 3 1 School of Veterinary Medicine, University College Dublin, Ireland 2 Devenish Nutrition Ltd., Belfast, Northern Ireland 3 School of Agriculture & Food Science, University College Dublin, Ireland

Introduction The transition period extends from 3 weeks before to 3 weeks after calving It is the most critical period of the lactation – Nutrition and energy balance – Production – Metabolic Health Issues Economic and welfare implications

Introduction INPUTS OUTPUTS ENERGY BALANCE Energy balance can be assessed during transition by body condition score change

Previous Studies Have been concerned with the implications of cows reaching target BCS at various stages of lactation However, little is known about the effect of BCS change immediately pre-calving on the lactation characteristics of the dairy cow StageBody Condition Score Dry off2.75 – 3.00 Calving3.00 – 3.25 BreedingMinimum to 250 days in milk2.75 – 3.00 (Mulligan, 2012)

Objective To determine if change in BCS in the last 15 days before calving has an affect on subsequent lactation characteristics

Materials and Methods Commercial Irish dairy farm 98 Spring-calving Holstein-Friesian cows 305 day yields Milk (kg)9125 Fat (kg)331 Protein (kg)298 Fat (%)3.62 Protein (%)3.27 SCC (‘000 per ml)308 Calving Interval (days)445

Treatments MAINLOSS Parity 1N238 ∆ BCS Parity 2N1215 ∆ BCS Parity 3N20 ∆ BCS MAIN– cows that maintained BCS 15 d prior to calving LOSS – cows that lost BCS 15 d prior to calving

Body Condition Scoring 1 to 5 BCS scale (Edmonson et al., 1989) Same trained researcher every 2 weeks Eliminate inter-observer variation

Dairy Cow BCS

Body Condition Score (BCS) Records Analysis

Milk Sampling Cows milked at 0700 and 1600 h daily Milk was sampled every two weeks – Mid infrared spectrophotometry – Milk, fat, and protein yields – Fat, protein, and lactose concentrations Energy Corrected Milk (KirchgeBner 1997) (Milk yield x ) + (Fat yield x 12.86) + (Prot yield x 7.04)

Lactation Curve Modelling Woods Incomplete Gamma Function (Woods, 1967) Non-linear function y(t) = at b e -ct – t = time – a = estimate of initial milk yield – b= rate of increase until peak production – c = rate of decrease after peak production

Curve Shape ShapeParameterCurve Shape description bc C1+-Standard lactation curve C2++Continuous increase C3--Continuous decrease C4-+Inverted lactation curve a b c

Lactation Curve Characteristics Initial milk yield (a) Rate of increase to peak yield (b) Rate of decline after peak yield (c) Lactation persistency (p) Time at which peak yield is attained (Tm) Peak yield (Ym)

Statistical Analysis Y ijkl = BCS + C i + T j + P k + TP jk + TC ij + PC ki + e ijkl Y ijkl = lactation curve characteristics of the l th cow in ith calving month, the jth treatment, and the kth parity, BCS = covariate of BCS on d -15 C i = the i th calving month of Jan, Feb, Mar, or Apr T j = the j th treatment of MAIN or LOSS P k = the k th parity of 1, 2, or ≥ 3 TP jk = the interaction of the j th treatment and the k th parity TC ij = the interaction of the j th treatment and the i th calving month PC ij = the interaction of the k h parity and the i th calving month e ijkl = random residual error

Results: Milk (kg) MAINLOSSSignificance Parity 1Parity 2Parity 3Parity 1Parity 2Parity 3TPT × P Milk a (2.34) (2.75) (2.23) (3.53) (2.67) (2.16) <0.05NS c Aa (0.0005) (0.0004) B (0.0004) b (0.0007) (0.0005) (0.0005) <0.10NS tmtm ACc (4.35) B (4.20) D (3.63) d (6.04) (4.07) (3.12) <0.10NS YmYm CE (1.21) D (1.42) F (1.24) E (1.74) EF (1.31) F (1.06) NS<0.01NS

Results: Fat (kg) MAINLOSSSignificance Parity 1Parity 2Parity 3Parity 1Parity 2Parity 3TPT × P Fat kg P 6.62 a (0.10) 6.41 (0.19) 6.42 (0.14) 6.15 b (0.23) 6.44 (0.16) 6.33 (0.14) NS tmtm (6.12) (8.11) c (5.78) (12.12) (6.99) d (5.87) NS YmYm 1.11 E (0.04) 1.34 F (0.06) 1.33 F (0.04) 1.25 (0.09) 1.24 A (0.05) 1.37 B (0.05) NS<0.05NS

305 Day Production Yields MAINLOSSSignificance Parity 1Parity 2Parity 3Parity 1Parity 2Parity 3TPT × P Milk (kg) CE (240.35) DE (284.42) F (232.48) E (362.43) AF (276.44) BF (224.38) NS<0.01NS Fat (kg) E (16.24) C (20.58) DF (16.48) (25.59) (19.10) (16.11) NS <0.01NS Prot (kg) E (6.69) CF (7.92) DF (6.47) E (10.09) EF (7.69) F (6.25) NS<0.10NS SCC (,000) A (63.41) (58.62) aB (48.37) C (88.61) (59.04) bD (45.65) <0.05 NS

Summary Overall – MAIN significantly greater initial milk yield (a) than LOSS – MAIN significantly lower SCC than loss – LOSS cows tended to reach peak milk yield sooner – LOSS cows tended to have a faster rate of decline post peak Parity 1 – MAIN took longer to reach peak milk yield – MAIN lower rate of decline post peak milk yield – MAIN more persistent fat yield curve Parity 3 – MAIN took longer to reach peak fat yield – MAIN had lower somatic cell count

Conclusion Ideal lactation curve – Cows that reach peak milk and component yields slowly and remain persistent – More beneficial to the cows’ metabolic and health status (Solkner and Funchs, 1987) Therefore MAIN parity 1 and parity 3 cows had improved lactation curve characteristics compared to LOSS parity 1 and parity 3

Thank you for your attention

The effect of body condition score change 15 days prior to calving on lactation curve and production parameters in grazing dairy cows in Ireland M.R. Sheehy* 1,2, F.J. Mulligan 1, M.A. Crowe 1, S.P.M. Aungier 1, and A.G. Fahey 3 1 School of Veterinary Medicine, University College Dublin, Ireland 2 Devenish Nutrition Ltd., Belfast, Northern Ireland 3 School of Agriculture & Food Science, University College Dublin, Ireland

Lactation Curve Characteristics Initial milk yield (a) Rate of increase to peak yield (b) Rate of decline after peak yield (c) Lactation persistency (p) – p = -(b+1)*ln(c) Time at which peak yield is attained (Tm) – Tm =b/c Peak yield (Ym) – Ym = a(b/c) b e -b