Dados do Trabalho

Título

Energy Corrected Milk Yield of Holstein Cows in Organic HighInput and Low-Input Feeding Systems

Titulo em português

Leite Corrigido para Energia de Vacas Holandesas em Sistemas de Alimentação Orgânica de High-Input e Low-Input

Introdução (obrigatório)

Organic milk production plays a crucial role in Europe sustainable agriculture, with increasing efforts to expand the number of organic farms. However, factors such as animal feeding and seasonal variations significantly affect the efficiency and quality of organic dairy production (BLANCO-PENEDO et. al., 2019).
In organic systems, the seasons significantly impact milk production because the cows feed is primarily produced on the farm, making the quality of forage consumed by the animals crucial.
In general, milk yields are higher in feeding systems that contain high amounts of corn silage and concentrates as energy sources compared with pasture-based systems due to the physiological factors of the animals and their increased susceptibility to variations in forage quality (EISERT 2019).
The objective of this study is to understand how different feeding regimes, (high-input vs. low-input) impact the milk yield in organic milk production systems.

Material e métodos (obrigatório)

 The study was conducted at the Gladbacherhof Experimental Farm, Justus Liebig University (JLU) Giessen, Germany, utilizing a herd of Holstein cows raised under an organic production system. This experiment is part of the GreenDairy project, which focuses on integrated animal and plant production to assess the environmental impacts of various cow feeding systems. The cows were divided into two groups: one receiving a high-input (HI) diet, which included corn silage and a higher amount of concentrate (6.7 Kg/cow/day), and the other on a low-input (LI) diet, which excluded corn silage and involved a lower concentrate amount (4.2 Kg/cow/day) Before the start of the project, both groups were receiving a HI diet. The transition from the HI diet to the LI diet was conducted over a period of 14 weeks. Each group was kept separate in the dairy barn, with access to a Lely A5 automated milking system (AMS). The AMS collected individual data on milk volume, fat and protein content, at each milking time. Data collection was conducted over one year, from June 2023 to June 2024. Information from 143 dairy cows, totaling 32,895 data points, was used. The energy-corrected milk yield (ECM) was calculated using the equation: ECM = (0.327 * Milk Yield MY) + (12.95% * Fat * MY / 100) + (7.65% * Protein * MY / 100) (TYRREL & REID, 1965). A variance analysis was conducted using the MIXED model (SAS). The REML model included the fixed effects of feeding group (HI and LI), season, days in milk (DIM), and lactation number (LN – 1, 2 or 3+ and more lactations), as well as the interaction between feeding group and LN and the interaction between feeding group and season. The significance level was set at P<0.05.

Resultados e discussão (obrigatório)

The study investigated the ECM yield of cows under HI and LI feeding systems, with particular attention to lactation number and season. The findings are summarized in the Table 1. Table 1: Milk yield (kg ECM +- standard deviation) of the High-input and Low-input feeding group, separated lactation number and season.   ECM   High- Input Low - Input  Yield Average  27.8 ± 0,60 A 19.1 ± 0,57 B  Lactation Number 1 27 ± 0,61Ab 20.6 ± 0,59 Ba 2 27.1 ± 0,61 Ab 19.5 ± 0,58 Bb  3+ 29.4 ± 0,61 Aa 17.24 ± 0,59 Bc  Season Winter  28+0,60 Ab 19.5 ± 0,57 Bb Spring 28.8 ± 0,60 Aa 20.8 ± 0,58 Ba Summer 27 ± 0,60 Ad  18.4 ± 0,57 Bc Autumm 27.5 ± 0,60 Ac 17.6 ± 0,58 Bd Uppercase letters indicate differences within rows, while lowercase letters represent differences within columns. Significance level p < 0.05.  Cows in the HI group have more ECM than those in the LI group.  ECM yield was over 8 kg higher in the HI group (27.8) compared to the LI group (19.1). An interaction was observed between feeding system and lactation number. In the HI group, ECM increased with lactation number, peaking in third-lactation cows . The LI group showed a decrease with increasing lactation number. First-lactation cows in the LI group yielded 20.6 kg, while third-lactation cows yielded only 17.2 kg. The decrease in ECM for older cows in the LI group may be due to their sensitivity to changing from a HI to a LI diet since we start our data evaluation right after we finished our 14 weeks transition period from the HI to the LI diet. The first-lactation cows, that calved for the first time on the evaluation period (calved from June 2023 to June 2024) did not have to go through the transition feeding, they receive already the LI diet from the start of their productive life, and this could result on a better adaptation. More evaluations have to be made to better understand this pattern along the time. Seasonal variations also influenced ECM yield. In the HI group, ECM yield was highest in spring (28.78 ± 0.60 kg) and lowest in summer (27 ± 0.69 0kg). The LI group had the highest ECM yield in spring (20.28 ± 0.58 kg) and lowest in autumn (17.6 ± 0.58 kg). These ECM yield trends were seen, likely due to changes in environmental conditions and forage quality.

Conclusão (obrigatório)

In conclusion, the findings underscore the critical role of corn silage and higher concentrate supplementation in maximizing milk production in organic dairy cows. Additionally, the results highlight that older cows in the LI system are more sensitive to diet changes.

Referências bibliográficas (opcional)

BLANCO-PENEDO, I., KRUUSE, E., EMANUELSON, U., FALL, N., KIRINO, Y., & NORRING, M. (2019). Organic Dairy Farming in Europe: Animal Health Management and Challenges to Sustainability. Frontiers in Veterinary Science, 6, 193. doi:10.3389/fvets.2019.00193

EISERT, J. Environmental impact of organic milk production: The case of low- versus high-input at Gladbacherhof. 2019. Thesis (PhD) – Universität für Bodenkultur Wien, Vienna, 2019.

TYRRELL, H.F.; REID, J.T. Prediction of the energy value of cow’s milk. J. Dairy Sci. 1965, 48, 1215–1223.