Invited review: Transitioning from milk to solid feed in dairy heifers

Abstract

Calves are born with a physically and metabolically underdeveloped rumen and initially rely on milk to meet nutrient demands for maintenance and growth. Initiation of solid feed consumption, acquisition of anaerobic microbes, establishment of rumen fermentation, expansion of rumen in volume, differentiation and growth of papillae, development of absorption and metabolic pathways, maturation of salivary apparatus and development of rumination behavior are all needed as the calf shifts from dependence on milk to solid feed. In nature and some production systems (e.g., most beef calves), young ruminants obtain nutrients from milk and fresh forages. In intensive dairying, calves are typically fed restricted amounts of milk and weaned onto starter feeds. Here we review the empirical work on the role of feeding and management during the transition from milk to solid feed in establishing the rumen ecosystem, rumen fermentation, rumen development, rumination behavior, and growth of dairy calves. In recent years, several studies have illustrated the benefits of feeding more milk and group rearing of dairy calves to take advantage of social facilitation (e.g., housing with peers or dam), and this review also examines the role of solid feed on rumen development and growth of calves fed large quantities of milk and reared under different housing situations. We conclude that the provision of high-starch and low-fiber starter feeds may negatively affect rumen development and that forage supplementation is beneficial for promoting development of the gut and rumination behavior in young calves. It is important to note that both the physical form of starter diets and their nutritional composition affect various aspects of development in calves. Further research is warranted to identify an optimal balance between physically effective fiber and readily degradable carbohydrates in starter diets to support development of a healthy gut and rumen, rumination behavior, and growth in young calves.

Caracterização físico-química e microbiológica do fluido ruminal e do conteúdo gastrointestinal de bezerros alimentados com silagem de leite de transição

“…O pH pode estabilizar com o tempo, principalmente pela ação tamponante da saliva ou pela capacidade da mucosa do rúmen em absorver mais rapidamente os ácidos livres resultantes da fermentação, (Dirksen, 1993). Segundo Khan et al (2016), a avaliação pontual não leva em consideração a variação diurna ou o comprimento e a extensão das condições das concentrações de ácidos ruminais, sendo mais indicada a avaliação contínua de pH ruminal em bezerros em desenvolvimento.…”

“…O rápido desenvolvimento desses compartimentos está associado ao tipo de manejo alimentar adotado durante a fase de cria (Khan et al, 2016). Pouco se conhece sobre os efeitos da administração da silagem de colostro ou de leite de transição na microbiota em formação do trato digestório dos ruminantes.…”

Desenvolvimento Dos Estômagos De Bezerros Aleitados Com Leite Em Pó E Soro De Queijo Em Pó Reconstituídos

“…O rápido desenvolvimento desses compartimentos está associado ao tipo de manejo alimentar adotado na fase de cria (Khan et al, 2016).…”

“…O rápido desenvolvimento desses compartimentos está associado ao tipo de manejo alimentar adotado na fase de cria (Khan et al, 2016).A capacidade de todos os compartimentos estomacais se modificam de maneira distinta com o avanço da idade dos bezerros, com uma aceleração do crescimento ruminal e uma retração do crescimento abomasal. Ao nascer, a atividade digestiva no bezerro é exercida pelo abomaso.…”

The effect of different physical forms of starter feed on rumen fermentation indicators and weight gain in calves after weaning

“…In nature, calves obtain nutrients from milk and forages. On dairy farms, calves are mostly fed restricted amounts of milk and weaned onto starter feeds (Khan et al 2016). Early transition to functional rumen microbial fermentation is economically important in dairy calves (Khan et al 2007).…”