Managing suckler herds so as to achieve a 365-day calving index should be regarded as an achievable target.<\/p>\n\n\n\n
This was one of the key messages delivered by Teagasc\u2019s Dr. David Kenny, who presented at the recent Agri-Food and Biosciences Institute (AFBI) beef open day.<\/p>\n\n\n\n
He also confirmed that reproductive efficiency is key to the economic and environmental sustainability of suckler beef herds.<\/p>\n\n\n\n
According to Dr. Kenny, fertility within beef herds is determined by four factors. <\/p>\n\n\n\n
These are: puberty and age at first calving; duration of the post calving anoestrous interval; heat detection efficiency, if using artificial insemination and bull fertility in herds using natural service.<\/p>\n\n\n\n
\u201cReproductive efficiency is a major factor determining the productivity and ultimately, profitability of beef cow enterprises.<\/p>\n\n\n\n
\n\u201cIn both the Republic of Ireland and Northern Ireland, there is evidence that less than 20% of heifers calves for the first time at 24-months-of-age and the calving-to-calving interval is frequently close to 400 days.<\/p>\n<\/blockquote>\n\n\n\n
\u201cReducing the age of first calving and calving-to-calving interval are also important for reducing the environmental footprint of beef production,” he said. <\/p>\n\n\n\n
Kenny stressed the absolute importance of managing replacement suckler heifers efficiently.<\/p>\n\n\n\n
These animals represent the next generation of cows in a herd and ideally each year\u2019s cohort of heifers should be genetically superior to their predecessors.<\/p>\n\n\n\n
Significant costs are incurred during the rearing of replacement heifers.<\/p>\n\n\n\n
Suckler <\/a>herds<\/h2>\n\n\n\n
It is imperative that these animal become pregnant early in their first breeding season, encounter minimal dystocia, are successfully re-bred to calve again within 365 days, and ultimately have long and productive lives within the herd.<\/p>\n\n\n\n
The Teagsc beef breeding specialist continued:<\/p>\n\n\n\n
\u201cResearch studies clearly show that delaying first calving from two years of age significantly increases costs.<\/p>\n\n\n\n
\n\u201cIndeed, beef heifers that conceived early during their initial breeding season and calved as two-year-old females have a greater probability of becoming pregnant as first calving cows, have greater lifetime production and tend to calve earlier in subsequent years.\u201d<\/p>\n<\/blockquote>\n\n\n\n
\u201cAge at which puberty occurs will impact on the time of conception in the first breeding season and, ultimately, lifetime productivity.<\/p>\n\n\n\n
\u201cAdditionally, conception rates are typically lower at the pubertal compared with subsequent heats.\u201d<\/p>\n\n\n\n
Research has confirmed that crossbred heifers typically reach puberty up to six weeks earlier than the average of their parental breeds.<\/p>\n\n\n\n
Larger European continental breeds of cattle are older at puberty than traditional British beef breeds or dairy breeds.<\/p>\n\n\n\n
However, breeds historically selected for milk production such as the Simmental, reached puberty at significantly younger than breeds such as the Charolais and Limousin.<\/p>\n\n\n\n
Dr. Kenny continued: <\/p>\n\n\n\n
\u201cReplacement heifers should reach approximately 65% of their mature body weight at the start of the breeding period.<\/p>\n\n\n\n
\u201cOn that basis, a high proportion of them will have reach puberty and conceive early in the breeding season.<\/p>\n\n\n\n
\n\u201cA 60 to 70% pregnancy target, to be achieved after three weeks of the breeding season should be set.\u201d<\/p>\n<\/blockquote>\n\n\n\n
Recommended 14-month live weight targets for a selection of suckler replacement heifer breed types follow: Aberdeen-Angus cross \u2013 370kg; Simmental cross \u2013 400kg; Limousin cross \u2013 420kg; Charolais cross \u2013 430kg.<\/p>\n\n\n