Relationships between protein and energy consumed from milk replacer and starter and calf growth and first-lactation production of Holstein dairy cows

摘要

The objective was to determine relationships betweenprotein and energy consumed from milk replacer andstarter and calf growth and first-lactation production ofHolstein heifer calves. Milk replacer and starter proteinintake and metabolizable energy (ME) intake data werecollected from 4,534 Holstein heifer calves for growthand 3,627 Holstein cows for production from birth yearof 2004 through 2014. Calves from 3 commercial dairyfarms were assigned to 45 different calf research trialsat the University of Minnesota Southern Research andOutreach Center, Waseca, Minnesota, from 3 to 195d of life. Calves were moved to heifer growers at 6 moof age, and calves were returned to their farm of birtha few weeks before calving. Most calves (85%) werefed a 20% crude protein and 20% fat milk replacer ata rate of 0.57 kg/calf daily. Metabolizable energy andprotein consumed from milk replacer and starter werecalculated for each individual calf for 6 and 8 wk ofage. Mixed model analyses were conducted to determinethe effect of protein and energy consumed fromboth milk replacer and starter on calf growth and firstlactation305-d production of milk, fat, and protein,adjusting for herd, season of birth, year, average dailygain (ADG), and calf trial. Calves with ADG ＞0.80kg/d consumed more combined protein and ME thancalves with lower ADG. Protein and ME intake fromcalf starter affected growth more than protein and MEintake from milk replacer because most calves were fedthe same fixed amount of milk replacer. Calves bornduring the fall and winter had greater combined proteinand ME intake than calves born during the springand summer. Milk replacer protein and ME intake didnot have a relationship with first-lactation 305-d milk,fat, and protein production. However, starter proteinand ME intake during the first 6 and 8 wk of age hada significant positive relationship with first-lactation305-d milk, fat, and protein production. Consequently,combined protein and combined ME intake had a positiveeffect on 305-d milk, fat, and protein production.Variance in protein and ME intake was high, suggestingthat additional factors affect calf growth during thefirst 8 wk of life and milk production in first lactation.