Whats a Good Age to Breed Beef Heifers

Selecting and Managing Heifers for Breeding

The backbone of a moo-cow calf production system is the choice and integration of heifers into the beef herd. The replacement rate varies considerably betwixt farms but on average lies between ten to 20%. The decisions around which cow to choose ranges from age of cow, breeding success, calf quality, rearing success, temperament of cow, moo-cow health etc. In the majority of cases, the historic period of the cow is the number one determinant on which moo-cow should be culled.

Since the replacement heifer is the foundation of a productive moo-cow herd, the choice of heifer and her development can greatly touch the economics of the farm operation through her genetics, future performance, and longevity. Time of first calving has a major influence on life time productivity, which is one of the most of import traits to consider. Enquiry has consistently shown that targeting first calving at 24 months maximises lifetime productivity, provided the cow continues to produce a calf each year. Research from Oklahoma State Academy College of Agriculture Sciences showed that heifers calving at 24 months produced 330 lbs of calf more over their lifetime than heifers calving at 36 months.

To dogie at 24 months, heifers must be bred by 15 months of age. The onset of puberty in cattle is determined by weight, age and brood. Weight is the major factor. The historic period at which puberty occurs is breed dependant with larger, later maturing breeds coming into puberty afterwards than smaller, before maturing breeds.

Table 1. Weight (lbs) at which fourteen - 15 month old heifers of different breeds reaches puberty.

% of heifers in oestrus	Angus	Hereford	Charolais	Angus x Hereford	Simmental x British	Lim x British
50	550	600	700	550	650	650
65 - seventy	600	650	725	600	700	700
85 - 90	650	700	750	650	750	750

Source: J. Field, OMAFRA

Tabular array 1 shows the result of weight on the % of heifers in a herd at 14 - 15 months of age which testify showtime heats, (onset of puberty). It demonstrates that before maturing breeds, i.e Angus, Heredford, reach puberty at a lighter weight than larger framed breeds, i.e. Charolais, Simmental. Farmers should bear these target weights in listen when selecting heifers to breed. Larger framed breeds must weight heavier at the target breeding appointment, i.e fifteen months, compared to smaller framed breeds. Feeding the correct nutrition to heifer calves, taking into account breed, is of import to ensure heifers reach their target weight by 15 months of age.

Replacement beef heifers should attain 65 to 70% of their potential mature weight past the time they are bred at 14-xv months of age. From weaning to beginning breeding, heifers should gain an average of 0.56 kgs to 0.80 kgs, (1.25 lbs to 1.75 lbs), per 24-hour interval or 115 to 160 kgs, (250 to 350 lbs), full (depending on breed). For most breeds and crosses, heifers should weigh between 300 to 390 kgs, (650 to 850 lbs.), at breeding time.

Lifetime productivity rates are afflicted by feeding management during critical phases. Research has shown that energy intake in excess of requirement can atomic number 82 to the infiltration of fatty into the developing udder which may restrict milk production in those heifers as cows afterwards in life. Poor milk product leads to poor calf functioning and earlier culling than planned for that animal.

Table 2. Nutrient Requirement for Replacement Heifers (growing at 1.25 lbs per day).

Medium Framed Heifers

Body Weight (lbs)	Dry Matter Intake (lbs)	Total Poly peptide (lbs)	TDN (lbs)
400	x.03	i.08	6.65
500	xi.86	1.xvi	7.86
600	13.60	1.24	9.01

Large Framed Heifers

Body Weight (lbs)	Dry Matter Intake (lbs)	Total Protein (lbs)	TDN (lbs)
500	12.75	i.24	7.82
600	14.61	1.33	8.97
700	16.41	1.41	10.07

Source: J. Field, OMAFRA

Table 2 shows the ideal nutrient requirement of growing heifers at various trunk weights. Medium framed heifers have a lower feed requirement at the aforementioned weight as large framed heifers. Producers must exist conscious of the frame type of heifer on their subcontract to avert underfeeding or overfeeding.

Producers should programme breeding of heifers at least 3 weeks earlier breeding the residue of the herd. Heifers accept longer to wheel mail calving than mature cows. By allowing a 3 week gap at breeding, start calf heifers will likely testify heats mail calving at the same time every bit the main herd. A breeding season of 45 days is adequate for heifers provided they are in skillful nutritional status. To maximise the return from heifers, information technology'south important to pregnancy check all heifers and cull those non in calf.

Heifers are very sensitive to calving difficulties. Enquiry by Ontario Veterinary Higher has shown that on average 22% of first dogie 2 year olds require help, and work by the University of Arkansas has shown that upward 34% of offset calf two year olds require help. Heifers must not exist over or underfed as both conditions can lead to calving difficulties. The nascency weight of the calf is related to genetics, less nutrition. Underfeeding will restrict the growth charge per unit of heifers, reduce the size of the pelvis and increase the charge per unit of calving difficulty. Overfeeding equally reduces the size of the birth canal due to backlog fat deposition.

First calf heifers should be separated away from the main herd prior to calving. Calving should exist monitored closely, but not obtrusively, to avert increasing stress on the animal (which may delay calving), and provide assistance where necessary. The calving process tends to take longer in start calf heifers versus mature cows.

Always check that the newborn calf has sucked. Commencement calf heifers are very inexperienced in allowing calves to suckle and help may be required. Great intendance must exist taken when treatment calves of heifers. A previously quite heifer may become extremely dangerous and unpredictable post calving.

The best method to reduce the risk of calving difficulties with start calf heifers is to breed heifers to an piece of cake calving bull. Calving ease is the relationship between calf birthweight and moo-cow pelvic size. Research has shown than in eighty% of cases where calves die at birth, they were normal, and presented in the correct "diving" position, but the cause of death was suffocation. These types of deaths are primarily due to a mismatch between dogie nascency weight and dam pelvic size. Calf birthweight varies betwixt breeds and within breeds, but a articulate distinction exists betwixt smaller framed, before maturing breeds and larger framed, afterwards maturing breeds. Producers should select bulls with low calf birth weight when breeding heifers.

Pelvic measurements have been used past some producers as a means of selecting heifers for breeding. The University of Nebraska has developed ratios that can be used to determine the dogie birthweight that a heifer could potentially successfully deliver. Measurements are taken at 12 to 13 months of age using a pelvimeter and from those measurements a maximum calf birthweight tin can exist adamant.

In Australia, pelvic measurements are primarily used as a alternative tool to successfully identify abnormally small or abnormally shaped pelvises rather than as a convenance option tool. These situations, if left unidentified, are associated with extreme calving difficulty, resulting in caesarean delivery and fifty-fifty death of the calf, cow or both.

Good selection and direction of heifers for breeding is critical to the genetic advocacy of the herd and the long term profitability of the beef farming enterprise.

References

Field, J. 2015, Feeding and Managing Replacement Beef Heifers, OMAFRA Fact Sheet.

Carson, Mark E., 2011, Preparing Heifers for Breeding, OMAFRA.

Lardner, Dr. Bart, 2014, Effect of Evolution System on Growth and Reproductive Performance of Beef Heifers. J. Anim. Sci. 7:3116-26.

Comerford, John W., 2011, Replacement Heifer Pick, PennState Extension.

Patterson, John, 2013, Tips to consider when selecting replacement heifers, Beef USA.

Patterson, David J., 1997, Pelvic Measurements and Calving Difficulty, University of Missouri Extension.

Troxel, Tom R., 2011, Pelvic Area Measurements in the Measurements of Replacement Heifers, University of Arkansas Agriculture and Natural Resources, FSA 3010.

Fahey, Thou., Boothby, D., Fordyce, G. and Sullivan, M. 2000, Female Selection in Beef Cattle, Queensland Beef Industry Institute, Q10047

lylescrianizied.blogspot.com

Source: http://www.omafra.gov.on.ca/english/livestock/beef/news/vbn0718a2.htm

Share this post