title: Divergence for residual feed intake of Holstein-Friesian cattle during growth did not affect production and reproduction during lactation.
abstract: Residual feed intake (RFI) is the difference between actual and predicted dry matter intake (DMI) of individual animals. Recent studies with Holstein-Friesian calves have identified an ~20% difference in RFI during growth (calf RFI) and these groups remained divergent in RFI during lactation. The objective of the experiment described here was to determine if cows selected for divergent RFI as calves differed in milk production, reproduction or in the profiles of BW and body condition score (BCS) change during lactation, when grazing pasture. The cows used in the experiment (n=126) had an RFI of -0.88 and +0.75 kg DM intake/day for growth as calves (efficient and inefficient calf RFI groups, respectively) and were intensively grazed at four stocking rates (SR) of 2.2, 2.6, 3.1 and 3.6 cows/ha on self-contained farmlets, over 3 years. Each SR treatment had equal number of cows identified as low and high calf RFI, with 24, 28, 34 and 40/11 ha farmlet. The cows divergent for calf RFI were randomly allocated to each SR. Although SR affected production, calf RFI group (low or high) did not affect milk production, reproduction, BW, BCS or changes in these parameters throughout lactation. The most efficient animals (low calf RFI) lost similar BW and BCS as the least efficient (high calf RFI) immediately post-calving, and regained similar BW and BCS before their next calving. These results indicate that selection for RFI as calves to increase efficiency of feed utilisation did not negatively affect farm productivity variables (milk production, BCS, BW and reproduction) as adults when managed under an intensive pastoral grazing system.
authors.affiliation: 1DairyNZ,Cnr. Ruakura & Morrinsville Rds,Hamilton 3240,New Zealand.
authors.forename: K A
authors.initials: KA
authors.lastname: Macdonald
authors.affiliation: 2DairyNZ,WTARS,42 Whareroa Rd,RD 12,Hawera 4672,New Zealand.
authors.forename: B P
authors.initials: BP
authors.lastname: Thomson
authors.affiliation: 1DairyNZ,Cnr. Ruakura & Morrinsville Rds,Hamilton 3240,New Zealand.
authors.forename: G C
authors.initials: GC
authors.lastname: Waghorn
mesh_terms: D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000254:growth & development* / Q000378:metabolism*; D004032:Diet / Q000662:veterinary*; D004435:Eating; D005260:Female; D007774:Lactation / Q000502:physiology*; D008892:Milk; D012098:Reproduction / Q000502:physiology*
keywords: feed efficiency; lactating cow; pasture; residual feed intake; stocking rate