Three-breed rotational crossbreds of Montbéliarde, Viking Red, and Holstein compared with Holstein cows for feed efficiency, income over feed cost, and residual feed intake

摘要

Rotational 3-breed crossbred cows of Montbéliarde,Viking Red, and Holstein (CB) were compared withHolstein (HO) cows for alternative measures of feedefficiency as well as income over feed cost (IOFC)and residual feed intake (RFI) during the first 150 dof first, second, and third lactations. Primiparous andmultiparous CB (n = 63 and n = 43, respectively) andHO (n = 60 and n = 37, respectively) cows were fedthe same total mixed ration twice daily with refusalsweighed once daily. Feed was analyzed for dry mattercontent, net energy for lactation, and crude proteincontent. Body weight (BW) was recorded twice weekly.Daily production of milk, fat, and protein were estimatedfrom monthly test days with best prediction.Measures of efficiency from 4 to 150 d in milk (DIM)were feed conversion efficiency (FCE), defined as fatplus protein production (kg) per kilogram of dry matterintake (DMI); ECM/DMI, defined as kilograms ofenergy-corrected milk (ECM) per kilogram of DMI; netenergy for lactation efficiency (NELE), defined as ECM(kg) per megacalorie of net energy for lactation intake;crude protein efficiency (CPE), defined as true proteinproduction (kg) per kilogram of crude protein intake;and DMI/BW, defined as DMI (kg) per kilogram ofBW. The IOFC was defined as revenue from fat plusprotein production minus feed cost. The RFI from 4 to150 DIM for each lactation was the residual error remainingfrom regression of DMI on milk energy output(Mcal), metabolic BW, and energy required for changein BW (Mcal). Statistical analysis of measures of feedefficiency and RFI for primiparous cows included thefixed effects of year of calving and breed group. Formultiparous cows, statistical analysis included breedas a fixed effect and cow as a repeated effect nestedwithin breed group. Primiparous CB cows had highermeans for FCE (+5.5%), ECM/DMI (+4.0%), NE_LE(+4.0%), and CPE (+5.2%) and a lower mean DMI/BW (–5.3%) than primiparous HO cows. PrimiparousCB cows ($875) also had higher mean IOFC than primiparousHO cows ($825). In addition, mean RFI from4 to 150 DIM was significantly lower (more desirable)for primiparous CB cows than HO cows. Likewise, multiparousCB cows had higher means for FCE (+8.2%),ECM/DMI (+5.9%), NELE (+5.8%), and CPE (+8.1%)and a lower mean for DMI/BW (–4.8%) than multiparousHO cows. Multiparous CB cows ($1,296) also hada higher mean for IOFC than multiparous HO cows($1,208) and a lower mean for RFI from 4 to 150 DIMthan HO cows.