Heritage chickens in pasture-based systems: Leveraging terminal crosses for genetic conservation, animal welfare, and enhanced profitabilit

Commodities

Practices

Intensive selection for commercial chicken breeds over ~50+ years has resulted in rapidly-maturing, extremely feed efficient commercial Cornish-cross broilers that excel in intensive, indoor production systems. However, in pasture-based systems these birds can suffer from poor welfare. For example, inadequate immune function and rapid growth-related cardiovascular compromise result in frequent mortalities (sudden death, parasitism, viral disease). Significant morbidities like injuries [e.g., fractures], cardiovascular collapse, and arthritis limit bird’s mobility and effective foraging. Despite these welfare issues, most regenerative farms continue to use commercial broilers because their rapid growth and high feed efficiency make economic sense. Heritage breeds offer an alternative with better foraging and less morbidity/mortality. These breeds also harbor critical genetic diversity. Intense genetic selection in commercial strains has wiped out their genetic diversity leaving them vulnerable to future challenges like climate change and new or emerging disease. Heritage breeds are the largest global reservoir for domestic chicken genetic diversity and conserving their diversity could be key to the species long-term survival. Despite being a requisite for future sustainability and a solution to welfare concerns,  heritage breeds are rarely used by regenerative farmers because their slow-growth and lower feed efficiency make them less profitable than commercial hybrids.

Despite heritage chickens’ potential, genetic improvement efforts are scattered and rarely documented with data. Our long-term goal is to develop economically-viable, locally-adapted heritage chickens that excel in pasture-based systems. In this project, we will improve heritage chicken production through selection and using hybrid vigor from terminal crosses. We believe optimizing production efficiency in heritage chickens represents an opportunity to increase small farm sustainability through increased profits, improved pasture utilization and optimized animal welfare. Importantly, increasing heritage breed use will create a reservoir of heritage genetic diversity needed to respond to future threats.

We will experiment with four heritage breeds well suited to our climate and production system, are among the faster-maturing breeds, and produce product with good table characteristics: New Hampshire (NH), Delaware (DEL), Buckeye (BUC), and American Bresse (BRE). Birds will be sourced from breeders that are selecting for production traits. In 2025, we will grow 100 broilers from each breed, and 100 broilers from two commercial hybrids: Freedom Rangers (FRE, a hybrid developed for pasture-based systems) and Cornish-Cross broilers (CC). Birds will either be hatched on our farm (NH) or purchased (see Budget). Growth rate, size, and feed efficiency will be calculated from successive weights over a 16 week period; welfare will be measured using the 11-part Welfare Quality^® Assessment Protocol (Butterworth et. al. 2009); and pasture use will be estimated using accelerometers data to quantify movement for two randomly selected broilers in each shelter (see Pearce et. al. 2023). Broilers will be assessed for additional indicators of production using the Livestock Conservency’s Assessment Protocol  on three occasions to identify individuals to keep as breeding pairs for 2026 (Appendix Figure 1A). A total of  600 hundred broilers will be grown out in two 300 bird batches (Figure 1B). After leaving the brooder after 3 weeks, birds will be housed in six  groups of 50. Each group will have a 12 x 8 ft. shelter (nighttime protection) with access to a 310 x 16 ft pasture access during the day. Individual birds will have ~1.5 sqft. of “indoor” and ~100 sqft. “outdoor” space (Figure 1C). Broilers will be slaughtered at ~6.5 lb live weight and carcass traits including dressing percent, cut size/proportion and cook loss determined for 10 birds in each of the 6 groups.

In 2026, breeding trios will be created from breeding birds identified in 2025. We will hatch 100 chicks for each heritage breed, and 100 chicks for each of 6 possible crosses between the purebred “parent” strains ( Figure 1B). Each cross will be reciprocal (i.e., in NH x DEL crosses 50 chicks will be NH father x DEL mother, and 50 chicks will be DEL father x NH mother). 400 purebred, 600 terminal cross, and 100 FRE, and 100 CC broilers will be grown out in four 300-bird batches. Data from each batch will be as described above for 2025. In addition, consumer tasting data will be collected during the on-farm field day (see Outreach).

Objectives. A few studies have evaluated heritage and heritage x commercial broiler crosses, but none have compared heritage x heritage crosses to purebred heritage and commercial broilers. Our objectives are to:

1) Compare production in heritage strains undergoing selection to production in heritage crosses and commercial hybrids.

2) Compare welfare and pasture utilization between heritage, heritage cross and commercial hybrids in our production system.

3) Measure production gains over a single generation of selection (i.e., 2025 to 2026) in heritage broilers compared to heterosis gains in heritage crosses.

4) Identify heritage breeds and crosses best suited to our local environment and system.