Feather meal is a rather inexpensive protein source, with high rumen undegradable protein (RUP). It is important to note that, at the time of writing (September 2020), its use in ruminant feeding is banned in the European Union (Regulation EC n° 999/2001, Annex IV) and in other countries such as Brazil (ABRA, 2020).
Degradability and digestibility
Values of in situ protein ruminal degradation of feather meal range from 40 to 60% (Mora-Luna et al., 2015; Habib et al., 2013; Scholljegerdes et al., 2005; Moreira et al., 2003; Loest et al., 2002; Bargo et al., 2001; Hernandez et al., 1998; England et al., 1997; Chiou et al., 1995; Blasi et al., 1991). Hydrolyzed feather meal was found to have a lower crude protein (CP) degradability than soybean meal (Mora-Luna et al., 2015) and than sunflower meal (Bargo et al., 2001). Protein from feather meal has a high intestinal true digestibility (Branco et al., 2006; de Oliveira et al., 2003; Rodriguez et al., 2003; Strzetelski et al., 1999; Lee et al., 1997; Calsamiglia et al., 1995). In wethers, at similar intake, hydrolyzed feather meal resulted in similar portal and hepatic nitrogenous nutrient flows (alpha-amino nitrogen, ammonia and urea) as other protein sources (soybean meal, corn gluten meal) (Branco et al., 2004).
Feather meal is an effective source of metabolisable protein and of sulfur amino-acids, mainly consisting in cysteine, while only very little methionine is available and could be limiting.
Dairy cattle
Feather meal can be an effective supplemental protein source for lactating dairy cattle in certain conditions. In mid-lactation Holstein cows, feather meal at 3% of DM intake was beneficial for milk production with maize silage diet at 14% CP but not at 18% CP; feather meal at 6% of DM intake, had no effect on DM intake and milk fat percentage, but reduced CP digestibility and milk protein concentration (Harris et al., 1992).
Indeed, despite a high level of metabolizable protein, the amino acid profile in feather meal can be limiting for milk production. Iso-metabolizable protein substitution of a balanced protein source by feather meal resulted in a decrease in DM intake, milk yield, milk protein content, and to a higher milk fat content (Stahel et al., 2014). Feeding hydrolysed feather meal above 6.7% of dietary DM decreased DM intake, leading to a linear decrease in milk yield and in milk protein concentration (Morris et al., 2020). When cows were given feather meal, the deficiency in specific amino acids compromised the increase in milk and protein yield in response to increasing the frequency of milking, as observed with a better amino acid balance (Yeo et al., 2003). In lactating dairy cows consuming a diet of grass silage and a cereal-based supplement containing feather meal, response of milk production to infusions of histidine revealed that this amino-acid is first limiting (Kim et al., 1999). In contrast, when associated to other protein sources to support metabolizable Met and Lys supply, feather meal gave comparable milk production than heat- and lignosulfonate-treated canola meal (Johnson-VanWieringen et al., 2007). A combination of feather meal and blood meal can be used as supplemental protein to support high milk production (>37 kg/day) in early lactation (Johnson et al., 1994). Feeding a combination of feather meal and blood meal was also found to increase milk production in dairy cattle (Grant et al., 1998).
In several cases, higher rumen undegradable protein supply provided by feather meal is not limiting for milk production, e.g. for cows on pasture producing less than 22 kg of milk (Bargo et al., 2001). In lactating beef cows fed ad libitum on brome grass hay, supplement as feather meal-blood meal combination had only little effect on body weight, condition score, milk production, or calf body weight compared to vegetable supplements (Encinias et al., 2005)
Beef cattle
At similar DM intake, feather meal led to higher or similar daily weight gain compared to other protein sources (urea or soybean meal) in crossbred (Charoles/RedAngus/Nelore) castrated calves fed sorghum (Vargas et al., 2003). In calves fed iso-metabolizable protein and energy diets based on 40% sorghum silage and 60% of concentrate, feather meal provided lower weight gains, higher intake and lower feed:gain ratio than the fish meal, soybean meal being intermediary (de Oliveira et al., 2002). Compared to soybean meal given at 1 kg/d from 45 days prior calving to the end of the breeding season in Brahman pregnant heifers, hydrolyzed feather meal induced lower body weight and condition score, but pregnancy rate was not affected (Mora-Luna, et al., 2014).
The lack of a response in protein efficiency to ruminally protected methionine and lysine suggested that feather meal as primary supplemental protein was adequate in these amino acids for growing calves (Klemesrud et al., 1998), but in a further experiment feather meal promoted a gain response equal to only 50% of the response obtained with rumen-protected Met (Klemesrud et al., 2000). The replacement of a traditional grain by feather meal higher in metabolizable arginine (56 to 175 mg/kg body weight), did not affect weight gain in grazing growing Limousin heifers (Johnson et al., 2019). When feather meal was incorporated into liquid supplements to replace a portion of the CP provided by urea, average daily gain and reproductive performance was improved in mature beef cows (Pate et al., 1995). Feeding a combination of feather and blood meals resulted in the best growth in calves (Blasi et al., 1991).
Sheep
In lambs, supplementation with feather meal had no effect on straw digestion in lambs (Thomas et al., 1994). In contrast, feather meal increased daily gain when it replaced soybean meal and urea or soybean meal alone (Thomas et al., 1994; Punsri, 1991). In wethers, substitution of soybean meal/urea by hydrolyzed feather meal produced an increase in protein intake and nitrogen retention, but also in feces and urine nitrogen excretion, while the digestibility of nutrients was reduced (Branco et al., 2003). The nitrogen utilization of diets was comparable when soybean meal was replaced by feather meal and blood meal (Viswanathan et al., 2009; Cozzi et al., 1995). In a diet containing 70% concentrate and at least 13% CP, differences in amino acid profiles among blood, corn gluten, feather, fish and soybean meals did not impact rate or efficiency of growth in crossbred (Boer x Spanish) wethers (Soto-Navarro et al., 2004). Wool fibre diametre and sulfur content of wool did not differ in lambs fed feather meal vs. soybean meal (Thomas et al., 1994).
Goats
The use of hydrolyzed feather meal with blood meal in dairy goats improved the nutritive value of the diet and milk quality (Andrighetto et al., 1994). Hydrolyzing the hard tissue (feather and bone) and coextruding it with soybean hulls resulted in a palatable by-product meal for meat goats, supporting nitrogen metabolism similar to that of traditional protein sources (Freeman et al., 2009). West African Dwarf goats fed 12.5% feather meal plus 12.5% rice husk showed encouraging results in terms of DM intake, and nutrient digestibilities (Belewu, et al., 2009).