Can we enhance fertility with grain? Chris Burke Farmers Forum Roadshow April 2015

Feed her grain Cow calves A miracle happens Cow is more fertile

How could grain help? Starch In theory, cow…. Cycles faster Glucose In theory, cow…. Cycles faster Stronger heats More fertile + Ovary Insulin 60-75% of DM is non-structural carbohydrate (NSC), 90% being starch. Gong et al., 2002; Garnsworthy et al., 2009; Burke et al 2010 Insulin-like Growth Factor 1(IGF-1)

We hypothesised that.. At a farm-system scale: …feeding 4 kg DM of maize/barley grain during the first 5 weeks after calving: Gets cows cycling faster Increases the 6-week in-calf rate What is the basis of this hypothesis?

The ‘carbohydrate’ study Conducted by Scott McDougall, Cognosco Funded by dairy farmers (DairyNZ Inc) and MBIE 900 cows in 3 commercial herds For 5 weeks after calving, cows assigned to: Starch diet: 4 kg barley/maize grain Fibre diet: 5 kg Soyhull/PKE (or pasture only) Starch diet – Non-fibre CHO = 34% Fibre diet – Non-fibre CHO = 22%

Did grain feeding improve fertility? Fibre Starch Sig. 3-wk Submission rate (%) 90 88 P = 0.05 Conception rate (%)* 58 53 P < 0.001 6-week in-calf rate (%) 84 79 Not-in-calf rate (%) 4 6 *to first AB during the first 3 weeks mating

Why didn’t grain improve fertility? Consistent with Irish studies (Kennedy et al., 2002 ) Complex interactions of feed substitution, BCS, DMI, genetics, timing, control group, etc. Grain did not get cows cycling faster Fibre Starch Sig. Calve to 1st ovulation* 31.0 28.9 n.s. Calve to 1st oestrus* 33.5 32.7 (*Subsample of 96 cows per herd, wkly milk progesterone by Shane Leane, Moorepark)

Take home message Reproductive performance is not improved with a high starch feed (e.g. grain) Go to the InCalf programme to navigate through the complexities of improving reproductive performance Improving reproductive performance should not be one of the reasons for feeding grain Nutrition is only part of it, and may not be what is limiting reproductive performance dairynz.co.nz/incalf

Can we enhance fertility with grain? Chris Burke Farmers Forum Roadshow April 2015

Not likely! The general conclusion was that: …. increasing the proportion of non-structural carbohydrate (NSC) in the early lactation diet reduced reproductive performance.

Extra slides beyond here:

5 wks postcalving 4 wks precalving Isoenergetic diets Pre: n.s Post: P = 0.01 Pre x Post: n.s 5 wks postcalving 4 wks precalving Burke et al., 2010 Isoenergetic diets Cows cycled 8 day faster when fed 5 kg DM grain after calving That increased the 6-wk in-calf rate by 17% Past-grain had an 81% first service conception rate (vs. 53-58%) But only 16 cows per treatment in a very well controlled study

Timeline Actual DMI for in-shed supplements Weekly pre- & post-grazed pasture mass Intake estimates Control diet* Early and late foetal-aging PDs AB Bull High NSC diet (grain) -4 (PSM) +5 +12 -12 Also measured PPAI (milks on d 21, 28, 35 & 42 +/- 3 d) and metricheck/BCS (d 28 +/- 3) in Herd 2 *Control diet – Low NSC supplement for Herds 1 & 3; pasture/pasture silage for Herd 2

Feed analysis estimates Herd 1 Herd 2 Herd 3 NSC Con Pasture 7.9 13.5 10.8 Maize silage 4.9 - 1.5 Pasture silage 1.1 PKE/DDG 3.6 Hay/Straw 0.3 Canola 0.2 Maize-barley grain (75:25) 4.0 4.1 PKE/soy hulls (50:50) 5.0 Total DM intake 16.8 17.8 18.7 14.6 16.4 17.3 ME (MJ) 248 242 229 171 206 199 Metabolisable protein (kg) 2.52 2.73 2.81 2.31 2.26 2.46 Non-fibre carbohydrate (%) 33.5 22.2 33.8 22.9 36.9 22.5

Did grain feeding improve health? Control High NSC Sig. BHBA (mmol/L) * (95% CI) 1.29 (0.82-2.02) 0.58 (0.42-0.78) P < 0.01 Subclinical ketosis (%) Clinical ketosis (%) Metricheck +ve (%) BCS *14 ± 3 d postpartum

Liveweight & Milk production Control High NSC Sig. Liveweight (kg) 449.4 448.0 P = 0.72 Milk volume (l) 21.9 22.3 P = 0.08 Fat % 4.50 4.57 P = 0.19 Protein % 3.78 3.77 Log SCC x 1,000 4.14 3.90 P < 0.01