# Are the recommended proportions of mature body weight being achieved in different stages of growth in Brazilian Holstein and Jersey dairy cattle?

## TL;DR

This study compares the growth patterns of Holstein and Jersey dairy cattle in Brazil, finding that Jerseys mature later than Holsteins and suggesting current feeding guidelines may need updating.

## Contribution

The study provides breed-specific mature body weight estimates and highlights the need for revised nutritional standards for different dairy cattle breeds.

## Key findings

- Holstein cows reach mature body weight by the third lactation, while Jersey cows do so by the fourth lactation.
- Jersey cows exceed recommended %MBW at first calving, indicating faster maturation.
- Both breeds meet target body weight growth standards in early life stages.

## Abstract

Summary: This study explored the relationship between live body weight (LBW) and mature body weight (MBW) in dairy cattle, focusing on Holstein and Jersey breeds. The research involved collecting LBW data across different cattle growth stages from 19 Holstein and 9 Jersey herds from Paraná State, Southern Brazil. Using nonlinear mixed models, the estimated MBW was 705 kg for Holsteins and 460 kg for Jerseys, with Jersey cattle maturing faster. Findings indicated both breeds met target BW (TBW) at critical growth stages, but primiparous Jerseys exceeded the recommended %MBW at first calving. While Holstein cows reached MBW by the third lactation, Jerseys achieved it by the fourth calving, similar to beef cattle. This suggests that current nutritional standards, currently based on Holstein data, need to be revised to accurately reflect the growth patterns of different breeds.

Summary: This study explored the relationship between live body weight (LBW) and mature body weight (MBW) in dairy cattle, focusing on Holstein and Jersey breeds. The research involved collecting LBW data across different cattle growth stages from 19 Holstein and 9 Jersey herds from Paraná State, Southern Brazil. Using nonlinear mixed models, the estimated MBW was 705 kg for Holsteins and 460 kg for Jerseys, with Jersey cattle maturing faster. Findings indicated both breeds met target BW (TBW) at critical growth stages, but primiparous Jerseys exceeded the recommended %MBW at first calving. While Holstein cows reached MBW by the third lactation, Jerseys achieved it by the fourth calving, similar to beef cattle. This suggests that current nutritional standards, currently based on Holstein data, need to be revised to accurately reflect the growth patterns of different breeds.

•MBW was estimated as 705 kg for Holstein and 460 kg for Jersey Brazilian cows.•Both breeds are within the recommended TBW growth in younger life stages (2, 6, and 13-15 months of age).•Brazilian Holstein cows reached the MBW in the third calving.•Brazilian Jersey cows reached the MBW in the fourth calving.

MBW was estimated as 705 kg for Holstein and 460 kg for Jersey Brazilian cows.

Both breeds are within the recommended TBW growth in younger life stages (2, 6, and 13-15 months of age).

Brazilian Holstein cows reached the MBW in the third calving.

Brazilian Jersey cows reached the MBW in the fourth calving.

The relationship between live BW (LBW) and mature BW (MBW) is critical for formulating optimal diets in dairy cattle, particularly regarding target BW (TBW) growth. Current nutritional guidelines suggest dairy cows reach MBW by the third calving (based on Holstein data), whereas beef cows reach it by the fourth calving. This study investigated LBW variations among different parities in Holstein and Jersey lactating cows, assessing the applicability of established proportion of MBW (%MBW) values across breeds. An observational study was conducted in dairy herds in Paraná State, Southern Brazil, comprising 19 Holstein and 9 Jersey herds, collecting LBW data at various growth stages. Nonlinear mixed models indicated MBW values of 705 kg for Holsteins and 460 kg for Jerseys, with Jersey cows showing faster maturation rate. Our findings revealed both breeds achieved recommended TBW verified by the %MBW at critical growth stages, but primiparous Jerseys exceeded the recommended values at first calving. Notably, while Holstein cows reach MBW by their third lactation, Jersey cows seem to achieve it by the fourth lactation, similar to beef cattle. This highlights the need for revised nutritional standards that better reflect the growth potential of different dairy breeds.