Providing calves different feed source early in life would not affect feed sorting and rumen fermentation for a long term

Abstract

This study aimed to investigate the short and long-term effect of early in life exposure to different feed sources on feed sorting and rumen fermentation of calves. Forty newborn female Holstein calves were randomly divided based on supplementation of concentrate (CON) or hay (HAY) only during the milk-feeding stage (d 1 to 56). After that, all calves were offered a total mixed ration (TMR) containing 43% of forage and 57% of concentrate until the end of the experiment (d 57 to 196). Calves were weighed immediately after birth and raised in individual hutches until d 70. The calves were then transferred to a heifer barn, housed within treatment in pairs (2 calves/pen). Rectal temperature, feed intake, body weight, body structural measurement, fecal and cough score were recorded ranges from day 1 to 196. Fresh and orts feed were sampled daily at the first two weeks (d 57-70) once TMR was offered and at the last week of the experiment (d 190 to 196) for analysis of feed sorting. Rumen fluid samples were collected at ranges from d 14-190 for detecting rumen pH and volatile fatty acids (VFA) concentrations. Our findings showed that early feed exposure did not influence calf health and growth performance but affected feed sorting in a short period. Upon transition to the same mixed diet, differences were found between treatments in the sorting of the different particle fractions. At week 9 and 10, calves early exposed to concentrates began to sort for fine particle fraction (primarily concentrate in this fraction), and against the long particle fraction (solely forage in this fraction), whereas calves early fed hay sorted for the long particle fraction, and against the fine particle fraction. However, no carryover effect was found, the differences between treatments fade away when detecting feed sorting at the last week, all calves sorted for short and fine particle fractions, and sort against long and medium particle fractions. Although the pattern of feed sorting initially differed between treatments, the rumen pH and VFA concentration were not altered once all calves transitioned to a TMR. These results suggested that the feed familiarity established early in life would not affect diet selection and rumen fermentation in heifer later in life, the dietary experience after transition to same TMR would eventually override the effect of early feed experience.