Langhill G x E Study

Background

High Energy (HE) and Standard Energy (SE) rations replaced Home-grown and By-product diets in May 2017. SE & HE  total mixed rations are fed ad lib to both Select (S) and Control (C) merit Holstein Friesian cows. Each of the four herds comprises of approximately 50 cows calving all year round. Cows are milked 3 times per day and continuously housed.

Feed rations

Dry Matter (DM) components of the rations in are shown in the bar chart below. The High Energy and Standard Energy rations are designed to supply DM 12.2 MJ/kg and 11.3 MJ/kg DM respectively. Rumen protected fat and straw each represent 2% of the HE diet.

Variables were extracted directly from the Langhill database for data obtained between 1st July 2017 and 2018. Figures were averaged by feed type and genetic group. Average daily milk production, feed intake, and live weight are illustrated. Milk composition, body condition and locomotion scores were measured fortnightly.

feeds diagram

Results

Outputs from the dairy systems will consider production, health and environmental effects of rations with contrasting forage and concentrate components, which contain different amounts of metabolisable energy.

The High Energy diet consists of approximately 4.5 tonnes of concentrate/cow/year and forages which include grass silage, whole-crop wheat and maize. The Standard Energy diet consists of approximately 1.5 tonnes of concentrate/cow/year and includes grass silage, whole-crop wheat and maize.

Average Yeild

The average yield of cows milking for at least 300 days in one lactation during the first year of the experiment is shown in the bar chart opposite. Select cows consuming a High Energy diet averaged 12,295 litres and control cows averaged 10,500 litres.

Select cows in the Standard Energy diet group averaged 10,329 litres and control cows average 8,669 litres.

On average Select cows in the High Energy diet group weighed 10kg more, consumed 4.1kg more feed and yielded 10.8 kg more milk per day than control cows in the Standard Energy group.

Average
July 2017 - 2018

Cows milking
/ month

Daily Feed
Intake (kg DM)

Daily Yeild
(kg)

Fat
(%)

Protein
(%)

Live Weight
(kg)

Condition
Score (1-5)

Locomotion
Score (1-5)

High Energy Select 44 22.7 38.4 4.05 3.39 640 2.1 2.4
Control 33 20.5 33.3 3.67 3.19 629 2.3 2.6
Standard Energy Select 51 20.0 29.2 4.36 3.38 626 2.0 2.4
Control 35 18.6 27.6 3.96 3.15 630 2.2 2.3

 

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