Lupinus angustifolius is a valuable species for ruminants. In Australia, blue lupin seeds are the main feed for sheep (Nelson et al., 2000). The high protein of blue lupin seeds makes them valuable alternative to soybean meal. Blue lupin seeds are more variable in terms of protein than white and yellow lupins. Blue lupin seeds have, like the other lupins, slightly higher energy than soybean meal in beef and dairy cattle (Berk et al., 2008). Blue lupin seeds can be used whole or ground, raw or roasted (Yu et al., 1999a; Yu et al., 1999b; Yu et al., 2001 ; Niwińska et al., 2011). As for white and yellow lupin seeds, the high rumen degradability of protein and amino acids may result in a low metabolisable protein (MP) value. Only scarce information could be found on the usefulness of roasting or grinding the seeds for better nutritive value. However, it can be inferred that processing could have the same effects as for white lupin seeds.
Degradability and digestibility
The rumen effective protein degradation coefficient (EPD) of blue lupin seeds assessed in sheep was found to be much higher (0.77) than that of soybean meal (0.65) but lower than that of yellow lupin seeds (0.82) (Niwińska, 2001; Zebrowska et al., 1997). The soluble fraction was much higher (60% vs. 20%) than that of soybean meal, and the degradable fraction was degraded more slowly in blue than in yellow lupin seeds (Niwińska, 2001). When blue lupin seeds were ground, it was shown that coarse grinding 5.7 mm vs. 1.0 mm decreased rumen degradability and increased the amount of protein digested in the small intestine (Niwińska et al., 2011). In lupin, only 3% of N and 2% of essential amino acids were absorbed in the intestine (Zebrowska et al., 1997).
Blue lupin seeds have relatively high digestibilities in ruminants. Digestibilities of OM, CP and EE were respectively 79%, 71% and 30% (Roth-Maier et al., 2003). Energy values were 11.9 MJ/kg DM for ME and 7.2 MJ/kg DM for NEL (Net Energy of Lactation), slightly higher than yellow lupin seeds, but much lower than white lupin seeds (-3 MJ for ME and -1.5 MJ for NEL) (Roth-Maier et al., 2003; Roth-Maier et al., 1995).
Technological treatments
Though only few experiments have been reported on the effect of treatments on the digestibility of blue lupin seeds, it is probable that processing would increase their nutritional value like in other lupin species.
Heat treatment
Dry roasting of whole white lupin seeds has been reported to significantly reduce the effective degradability of protein while increasing undegraded feed protein and starch and increasing the estimated intestinal digestion (Yu et al., 1999a; Yu et al., 1999b). The benefit of dry roasting was confirmed with blue lupin seeds fed in isoenergetic, isonitrogenous diets to 6 month old lambs (35 kg BW). Dry roasting resulted in increased ADG (+9-10 g/d) and increased gain to feed ratio (+8 g/d) in comparison to raw blue lupin seeds (Yu et al., 2001).
Tannin treatment
Condensed grape seed tannins reduced soluble and degradable fractions of blue lupin seeds, improving their protein efficiency (Bruno-Soares et al., 2011).
Sheep
Protein supplement
In Australia, blue lupin seeds are commonly used as a protein source in sheep diets. They are often used in control diets in experiments at levels varying from 35% to 70% for comparisons with other grain legumes such as Lathyrus cicera or lablab (Lablab purpureus) (White et al., 2002; Dixon et al., 1998). However, inclusion at 70% resulted in digestive upsets such as mild diarrhea and anorexia (White et al., 2002).
Roughage supplement
In a comparison with cowpea (Vigna unguiculata) and navy beans (Phaseolus vulgaris), lupins seeds were included at 10, 20 and 40 g/kg LW0.75 as a supplement to low quality roughage (50% chopped oaten hay and 50% barley straw) in a sheep (33 kg LW) diet, corresponding to 16, 32 and 59% of total DM intake (Paduano et al., 1995). Lupins resulted in increasing overall dietary intake, increasing liveweight gain, increasing wool growth and improved feed conversion ratio. The digestible OM intake was increased substantially with each increase in level of lupin supplement. The rapid disappearance of DM from lupin has suggested that lupins could mainly provide substrate for fermentation while bringing only a low proportion of rumen undegradable protein for digestion in the small intestine. This is consistent with results obtained by other authors with white lupins (Benchaar et al., 1994; Kibelolaud et al., 1993; Cros et al., 1992). Animals fed on lupins had higher growth performance than those fed no supplement but, contrary to what had been observed previously, lupins did not yield better results than the other grain legumes (Paduano et al., 1995; Holmes et al., 1991).
Concentrate and soybean meal replacer
In Ethiopia, sweet blue lupin seeds could potentially replace commercial concentrate supplement feed to a crop residue based diet. The relatively high protein content and low alkaloid content of blue lupin seeds combined with a good palatability to sheep suggested that lupin seeds could be used to replace other protein sources. Increasing levels of blue lupin seeds had no effect on DM, protein, ash and OM intake but resulted in a decreasing trend for body weight gain (Yeheyis et al., 2012). Washera lambs (17 kg BW) fed on natural pasture hay could be supplemented with increasing levels of blue lupin seeds during 90 days. Diets were designed in order to provide increasing levels of crude protein i.e. 110 g, 127 g and 144 g/d, with the intermediary level corresponding to NRC requirements for lambs (10 kg BW) (Nahom Ephrem et al., 2015). Increasing levels of blue lupin seeds increased the intake and digestibility of DM, protein and OM, as well as average daily gain. Optimal level was found to be the intermediary level providing 127 g/d crude protein with 150 g wheat bran and 245 g blue lupin seeds, corresponding to about 30% (DM basis) of blue lupin seeds in the diet (Nahom Ephrem et al., 2015).
In Poland, blue lupin cultivars with different alkaloid contents, sweet (0.10-0.12% alkaloids), semi-bitter (0.3%) and bitter (1.98%), were used to replace soybean meal in isonitrogenous diets (15% protein). Sweet and semi-bitter blue lupin seeds could replace soybean meal and yielded 180-188 g/d average daily gain, except for the seeds from the bitter cultivar which yielded significantly less gain (175 g/d) (Urbaniak, 1995). Other parameters such as carcass yield, dressing percentage, lean yield, bone and fat, wool production and wool sulphur content were similar in all diets (Urbaniak, 1999a; Urbaniak, 1999b; Urbaniak, 1995).
Cattle
Calves
Weaning calves were given increasing levels (0, 33, 67 and 100%) of steam-rolled blue lupin seeds as a complement of the concentrate and of a milk substitute during 15 weeks after weaning. Calves on 100% blue lupin seeds ate less, grew less rapidly and suffered anorexia from week 5 to 7. Blue lupin seeds were then abandoned. It was concluded that calves could be fed up to 67% blue lupin steam-rolled seeds without negative effect on rumen development or blood parameters (Hoang et al., 1995).
Heifers
In Chili, it was possible to finish heifers with a mixture of 60% barley whole crop silage and 40% concentrate made out of 38% blue lupine seeds (entire or ground) and 62% oat grain. Blue lupin seeds represented about 15% of the diet (Rojas et al., 2011). Grinding had no significant effect on daily intake or growth performance. The optimal cost was obtained with barley silage and whole grain of both oats and lupin (Rojas et al., 2011). In Belarus, blue lupin seed meal could be fed to 6-9 months heifers and had positive effects on digestibilities of DM, OM, protein and crude fibre compared to control (Kapustin et al., 1997). When fed to heifers of different classes of age (from 6 to 18 months), lupin seed meal resulted in all cases in higher average daily gains (Goryachev et al., 1997).
Steers
In Chile, finishing Hereford steers (9-10 month-old) had higher DM intake with blue lupin seeds in the diet than with white lupin seeds (6.23 kg vs. 5.74 kg DM overall dietary intake). The amount of blue lupin seeds was also relatively higher (25% DM intake vs. 22% for white lupin seeds) (Rojas et al., 1998). Finishing Hereford steers fed in similar conditions on ground or whole blue lupin seeds in a comparison with white lupin seeds showed no different performance when they were fed ground or whole seeds (Rojas et al., 1999). In Russia, Russian Black Pied bullocks were fed during 10 months on blue lupin seed meal at levels increasing with bullock age, from 6.5 to 20%. The use of blue lupin seeds resulted in improved growth, development and reproductive function when compared to pea seed meal diet (Vashchekin et al., 2005).
Dairy cows
In Australia, the use of blue lupin seed meal was assessed in a comparison with common vetch seed meal for high-yielding dairy cows in early lactation. The diet was based on a silage of wilted perennial ryegrass (Lolium perenne) and subterranean clover (Trifolium subterraneum) offered ad libitum, supplemented with 8 kg (fresh weight) of a mixture (50:50) of rolled-barley grain and a grain legume (lupin or vetch) and 1 kg concentrate including minerals. Lupin seed meal resulted in lower body weight gain (0.2 kg less than common vetch) but yielded more milk, milk fat and milk protein than common vetch seed meal (Valentine et al., 1996). This positive effect was confirmed later in Belarus where high-yielding cows receiving lupin seeds representing 4-10% of the nutritive value of the ration had higher milk productivity (+4.5-6.1%) and improved health (Goryachev et al., 2001). A study assessing the nutritive value of organically grown blue lupin in Denmark showed that high yielding cows could be fed on a grass-clover silage supplemented with a concentrate mixture containing barley grain and blue lupin seeds, either raw or heat treated, in roughly equal proportion. The study showed that the mixture containing untreated blue lupin seeds yielded similar results than cereals used in the control diet, while heat-treated lupin seeds tended to yield more milk (Mogensen et al., 2008).