Dados do Trabalho

Título

Zootechnical indexes: a comparative study between traditional and new herds under official milk-recording

Titulo em português

Índices zootécnicos: um estudo comparativo entre rebanhos tradicionais e novos sob controle leiteiro oficial

Contribuição para a sociedade (opcional)

This study is relevant and even unique because there are no previous studies (as far our knowledge goes) which compared traditional and new herds under official milk-recorded testing, including almost all dairy herds in the same region, since this study is the first one to encourage the practice of official DHI on all dairy herds associated with dairy cooperatives.

Introdução (obrigatório)

Zootechnical indexes are indicators used to evaluate the performance of dairy herds. They are based on quantitative and qualitative data, collected over time, and provide important information about the productive efficiency of dairy animals and profitability of dairy herds. In Paraná State, these indexes are measured by an official milk recording program, carried out by the Associação Paranaense de Criadores de Bovinos da Raça Holandesa (APCBRH), the most important DHI (Dairy Herd Improvement) organization in Brazil, with almost 70% of all Brazilian official milk-recorded cows. Despite their importance, there is no data (as far as our knowledge goes) on the relevance of measuring these indexes within herds, in a comparison between herds that have controlled these indexes for a longer time and the ones that just recently started to collect this information. This study aimed to compare these indexes between large and traditional herds, early adopters of the official milk-recording, with those observed in small and medium-sized herds, which began to be monitored only last year.

Material e métodos (obrigatório)

The present study compiled data from herds enrolled in the DHI service, from July 2023 to April 2024, from 247 dairy herds from the Campos Gerais region of Paraná State, Southern Brazil. From these 247 herds, 99 were categorized as traditional and more technologically advanced herds and 148 were categorized as new small and medium-sized herds. A total of 1,662 monthly reports were analyzed; 992 (59.7%) of which came from traditional and consolidated herds, which already carried out their official milk recording monthly and, consequently, obtained information on their zootechnical indexes. The other 670 (40.3%) reports refer to the new small and medium-sized herds, which began their monitoring in 2023. Within the official milk recording monthly reports, ten indexes were measured: average daily milk production, milk production corrected for 180 days in milk (DIM), DIM itself, milk fat %, milk protein %, milk lactose %, milk total solids %, somatic cell count (SCC), cows’ average age, and days open. SAS software version 9.4 (SAS Institute Inc., Cary, NC) was used for data editing and analysis. The effects of breed (Holstein, Jersey or mixed and crossbred) and herd’s category (new-DHI or traditional-DHI) were considered as fixed effects, whereas herd ID was included as a random effect. Data editing was carried out using MEANS and FREQ procedures of SAS, while associations of fixed and random effects were obtained using the MIXED procedure. A significance level of 5% was used in all tests.

Resultados e discussão (obrigatório)

Milk yield and milk yield corrected for 180 DIM Traditional herds showed higher (P<0.01) average milk production than new herds (29.44 vs. 21.66 kg/d), and milk production corrected for 180 DIM also was higher (P<0.01) in traditional herds compared to the new ones (32.35 vs. 22.66, respectively). Previous studies have shown that, typically, the size of the herd will affect daily production, where larger herds produced more kg of milk per day when compared to medium or small herds. Our present study corroborated the results found previously, showing that traditional and large dairy herds, typically well-established ones, have a considerably higher daily milk production than new herds that are still growing. Days in milk Days in milk did not differ (P=0.70) between traditional and new DHI herds: 201.6 vs. 203.1 d, respectively. Both traditional and new herds showed unsatisfactory results, above 180 DIM, which is considered a target for dairy herds.  Milk fat, milk protein, and milk total solids contents No differences were found between traditional and new herds for milk fat content (3.98 vs. 3.99%; P=0.85), milk protein content (3.42 vs. 3.41%; P=0.66), and milk total solids content (12.94 vs. 12.86%; P=0.16), suggesting that the payment system for milk components adopted by the Pool Leite, an integrated system of the three main cooperatives in the region, benefits both large and traditional herds, as well as small and medium herds.  Milk lactose and somatic cell count The percentage of lactose was significantly higher (P<0.01) in traditional herds than in the new ones (4.58 vs. 4.49%, respectively). Average somatic cell count in large and traditional herds was lower (P=0.03) than on smaller and newer herds (277.4 vs. 357.9 x103 cells/mL). The higher lactose content and the lower SCC suggest that large and traditional herds produce milk with superior quality which can be explained due to the several years of monitoring these indexes, where the early identification and treatment of infections such as subclinical mastitis and constant search for improvement, resulted in higher milk quality delivered to the industry. Cow’s average age Average age of the cows also differed (P<0.01) between herds: 50.2 vs. 61.1 months for traditional and new herds, respectively, showing that traditional herds cull cows more intensively than the new ones. Larger herds tend to cull more cows than small or medium herds, either because they are already stabilized or because they adopt a higher herd replacement rate. Days open No differences were found (P=0.46) for days open between traditional and new herds (149.9 vs. 155.3 d, respectively), suggesting that both herds must improve their reproductive indexes. 

Conclusão (obrigatório)

Our results suggest that large and traditional herds produced more milk, with slightly better milk quality indexes, but their cows have a shorter productive life, being discarded around one lactation earlier than cows from small and medium-sized and new-DHI-adopter’s herds. In general, herds which have been carrying out this measurement for a longer time through official milk recording showed better indexes when compared to herds which started recently. These results suggest that it is only possible to evolve and advance in the productivity and profitability of the dairy business when zootechnical indexes are measured in a regular basis.