Early lactation pasture allowance and duration: the effect on bodyweight and body condition score in cows

HAL Id: hal-02738945

https://hal.inrae.fr/hal-02738945

Submitted on 2 Jun 2020

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Early lactation pasture allowance and duration: the effect on bodyweight and body condition score in cows

E. Kennedy, Luc Delaby, J. Roche, Brendan Horan, E. Lewis

To cite this version:

E. Kennedy, Luc Delaby, J. Roche, Brendan Horan, E. Lewis. Early lactation pasture allowance

and duration: the effect on bodyweight and body condition score in cows. 26. General meeting of

the European Grassland Federation (EGF), Sep 2016, Trondheim, Norway. Wageningen Academic

Publishers, Grassland Science in Europe, 21, 2016, The multiple roles of grassland in the European

bioeconomy. �hal-02738945�

Grassland Science in Europe, Vol. 21 – The multiple roles of grassland in the European bioeconomy 495

Early lactation pasture allowance and duration: the effect on bodyweight and body condition score in cows

Kennedy E.¹, Delaby L.³, Roche J.², Horan B.¹ and Lewis E.¹

1

Teagasc, Animal & Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland;

Down to Earth Advice Ltd., P.O. Box 12520, Chartwell, Hamilton, New Zealand;

INRA, AgroCampus Ouest, UMR 1348, Physiologie, Environnement and Génétique pour l’Animal et les Systèmes d’Elevage, 35590 Saint-Gilles, France; emer.kennedy@teagasc.ie

Abstract

Feed deficits can occur in grazing systems due to low spring grass growth. The objective of this experiment was to investigate if different pasture allowances (PA) offered to early lactation grazing dairy cows for varying time durations influenced bodyweight (BW) and body condition score (BCS; 5 point scale). The two-year experiment offered cows one of four PA (60, 80, 100 or 120% of intake capacity), for either 2 or 6-weeks. Once the 2- and 6-week time durations had elapsed, the cows were offered 100% PA. At the end of the first 2 weeks, there was a linear increase in BW with increasing PA (441, 449, 456 and 464 kg, respectively), but there was no effect of PA on BCS (2.99). There was no effect of the interaction between PA and duration on BW at the end of week 6; BW increased linearly with increasing PA (443, 453, 456 and 466 kg; 60, 80, 100 and 120%, respectively), but, there was no effect of PA or duration on BCS at the end of 6-weeks (2.91). After 10-weeks there were no differences in BW or BCS. However, these results cannot be examined in isolation; other variables such as milk production and fertility need to be considered in order to obtain a complete picture of the residual effects of altering PA in early lactation.

Keywords: pasture allowance, early lactation, bodyweight, body condition score, dairy cow

Introduction

Increased pasture utilisation can reduce the feed costs associated with dairy production systems and increase profitability (Shalloo et al., 2004). An increase in grass utilisation is generally achieved with lower post grazing sward heights, but this results in lower pasture allowances being offered to grazing dairy cows (Ganche et al., 2013). Furthermore, feed deficits can lead to lower pasture allowances in grazing systems due to low spring grass growth which can result in the mobilisation of body reserves as cows try to balance the deficit between reduced energy intake and early lactation milk production requirements. The objective of this experiment was to investigate if different pasture allowances (PA) offered to early lactation grazing dairy cows for varying time durations influenced bodyweight (BW) and body condition score (BCS; 5 point scale).

Materials and methods

The study was undertaken over a two year period; from March 25 to November 27, 2014 and March 9 to November 23, 2015 at the Teagasc Moorepark research farm, Fermoy, Co. Cork, Southern Ireland.

Each year 96 dairy cows (41 primiparous and 55 multiparous in year one (Y1); 24 primiparous and 72 multiparous in year two (Y2)) were assigned to a randomised complete block design with a 4×2 factorial arrangement of treatments. Cows were completely re-randomised in 2015. Cows were balanced and randomly assigned to one of four PA (60, 80, 100 or 120% of intake capacity; IC) for either 2 or 6 weeks. Once the 2- and 6-week time durations had elapsed, the treatments were offered 100% of IC.

No concentrate was offered to cows during the experiment. Intake capacity was calculated using the equation of Faverdin et al. (2011) based on age, parity, days in milk, BW, BCS and potential milk yield.

Pastures were >80% perennial ryegrass. Fresh pasture areas were offered after each milking during the

treatment period and on a 24-hour basis thereafter. Pre- and post-grazing sward heights were measured

496 Grassland Science in Europe, Vol. 21 – The multiple roles of grassland in the European bioeconomy

daily using a rising plate meter. Herbage mass (HM; >3.5 cm) was measured twice weekly. Treatment groups grazed adjacent to each other to ensure similar HM was offered. Pasture allowance (>3.5 cm) for the 60, 80 and 120% treatments were calculated based on the IC of the 100×6 treatment, the mean IC value of all animals in the 100×6 group was used. As HM was similar between treatments daily area allocations were different. An electronic portable weighing scale with the Winweigh software package (Tru-test Limited, Auckland, New Zealand) was used to record BW weekly. Body condition was scored by the same individual throughout the study on a weekly basis using a scale from 1 to 5 (where 1 = emaciated and 5 = extremely fat) with 0.25 increments (Edmondson et al., 1989). Data were analysed using covariate analysis and mixed models in SAS v9.3. Fixed terms for year, parity, breed, PA, duration and the interaction of PA and duration were included, with cow as the random effect. Pre-experimental values were used as covariates.

Results and discussion

The mean PA for the 60, 80, 100 and 120% treatments for the first two weeks were 8.0, 10.7, 13.4 and 16.0 kg dry matter (DM) cow

day

, respectively (P<0.001). This resulted in post-grazing heights (PGH) of 2.4, 2.9, 3.5 and 4.1 cm, respectively (P<0.001). The mean PA and PGH during weeks 3-6 were 9.1, 12.1, 15.1, 18.2 kg DM cow

day

and 2.5, 3.1, 3.8, 4.3 cm for the 60, 80, 100 and 120% 6-week treatments. PA and PGH for the 2-week treatment, which was grazed as a single herd during weeks 3-6, were 14.8 kg DM ha

and 3.7 cm, respectively.

There was no interaction between PA and duration on BW or BCS. At the end of the first 2 weeks of the experiment, BW increased linearly with increasing PA (441, 449, 456 and 464 kg, respectively; Figure 1).

For each percentage increase in PA cow BW increased by 0.38 kg. At the end of the six-week experimental period, there was no interaction between PA and duration but there was an effect of PA (P<0.001) and duration (P<0.01) on cow BW. Similar to the first two-weeks of the experiment BW increased linearly with increasing PA (443, 453, 456 and 466 kg, respectively). At the end of the six week experimental period the linear increase in BW was the same as at the end of the first two-weeks – for each percentage increase in PA cow BW increased by 0.38 kg. Bodyweight was similar for all PA treatments at the end of the tenth week (464 kg). Kennedy et al. (this volume) reported that the 60x6 treatment reduced their yield of milk fat plus protein during this six-week period, indicating that these cows reduced their energy output rather than excessively mobilising body reserves to maintain milk production. Given the

400 410 420 430 440 450 460 470 480

1 2 3 4 7 8 9 10

kg

5 6

Week of experiment

60x2 60x6 80x2 80x6

100x2 100x6 120x2 120x6

Figure 1. Bodyweight profile of early lactation dairy cows offered 1 of 4 pasture allowances (60, 80, 100 or 120% of intake capacity) for either 2 or 6 weeks.

Grassland Science in Europe, Vol. 21 – The multiple roles of grassland in the European bioeconomy 497

difference between the treatments (<20 kg) they may have been a result of differences in gut fill. This is further reinforced when BCS was observed as there was no effect of PA or duration on the herd average BCS after either two (2.99) or six (2.91) weeks on treatment.

Conclusions

Any differences in BW observed when different PAs were imposed may have been due to differences in gut fill as no difference in BCS at any of the time points were evident. However, the results of this experiment need to be considered alongside milk production, fertility and behaviour and welfare measurements to draw definite conclusions and to understand the true effect of offering different PA for different durations of time to cows in early lactation.

Acknowledgements

The authors wish to thank the Moorepark farm staff and technicians for their care of the experimental animals and assistance with experimental measurements. This experiment was funded by Teagasc Core Funding and the Irish Dairy Levy.

References

Edmondson A.J., Lean I.J., Weaver L.D., Farvver T., and Webster G. (1989) A body condition scoring chart for Holstein dairy cows.

Journal of Dairy Science 72, 68-78.

Faverdin P., Baratte C., Delagarde R., and Peyraud J.L. (2011) GrazeIn: a model of herbage intake and milk production for grazing dairy cows. 1. Prediction of intake capacity, voluntary intake and milk production during lactation. Grass and Forage Science 66, 29-44.

Ganche E., Delaby L., O’Donovan M., Boland T.M., and Kennedy E. (2013) Direct and carryover effect of post-grazing sward height on total lactation dairy cow performance. Animal 7, 1390-1400.

Shalloo, L., Dillon P., O’Loughlin J., Rath M., and Wallace M. (2004) Comparison of a pasture-based system of milk production on a high rainfall, heavy-clay soil with that on a lower rainfall, free-draining soil. Grass and Forage Science 59, 157-168.