Dunne calves 100 continental-type cows in 10 weeks from the beginning of February. His farm comprises just under 300ac, split into two large blocks.
There are three bulls currently in the herd, their pedigree and relevant trait index values are outlines below (May 2017 evaluation):
Aberdeen Angus
Charolais
Simmental
John plans to increase his cow numbers from 100 to 120 during the BETTER farm programme to help bolster farm output. Up until this year, no heifers from the Aberdeen Angus bull – heifer’s heifer calves, that is – have been kept as replacements.
However, owing to the fact that John is looking to increase numbers relatively quickly, he is considering breeding from some of these Angus-sired animals.
At a recent farm planning meeting, six heifers were identified as being suitable to breed. They all weighed in excess of 380kg and had five stars on the replacement index.
Though their figures point towards easy calvings, Dunne is hesitant to let these heifers to his Charolais or Simmental bulls. Obviously, they cannot be bred by his Angus bull, their sire, so John is using AI for the very first time.
On such a big holding, labour is an issue – Dunne does not have a lot of free time for heat detection and is not yet set up to round up animals at ease. Synchronisation of oestrus represents his best option for breeding these heifers to AI.
Relative to mature cows, heifer synchronisation is much cheaper working out at €6 to €7/head (not inclusive of AI straw).
Options
Dunne has two options.
He can heat-detect the heifers for six days, serving any animals displaying heat and then inject non-bred animals with estrumate (2cc) on day six. These animals should come into heat between days seven and 11.
Alternatively, he can reduce the necessary heat detection period by injecting all animals with estrumate, serving any animals in heat during the following three to four days and then injecting any non-served animals a second time on day 11.
Again, he will bull to standing heats in the subsequent three to four days after the second injection.
Listen to “Ciarán Lenehan speaks to BETTER farmer John Dunne” on Spreaker.
Given it’s his first time using AI, Dunne must be clear on a couple of principles. Heat detection cannot be rushed.
During the periods where he is expecting heats, he must spend 15 to 20 minutes with the cattle three times daily. He will use scratch card-based heat detection patches to help pick up heats.
Dunne will also adhere to the AM/PM rule – animals standing in heat in the evening will be bulled the following morning and vice versa.
Given the good weather, seemingly good breeding and good quality grass that Dunne has ahead of these heifers – fertility should not be an issue.
Provided he gets his management right, it is questionable whether he should repeat serve any of these heifers should they not hold to first service.
This might seem needlessly ruthless, but fertility is exceptional in the herd at present with an average calving interval of 375 days.
Dunne wants only the most fertile heifers incorporating into his herd to maintain and potentially improve this performance.
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