Feedipedia
Animal feed resources information system
Feedipedia
Feedipedia

Pearl millet (Pennisetum glaucum), forage

Datasheet

Description
Click on the "Nutritional aspects" tab for recommendations for ruminants, pigs, poultry, rabbits, horses, fish and crustaceans
Common names 

Pearl millet, candle millet, dark millet, bajra, indian millet, horse millet [English]; bulrush millet [English/Australia]; cattail millet [English/USA]; mahangu [English/Namibia]; mijo perla, mijo negro, panizo mamoso [Spanish]; mil à chandelle, millet perle, mil pénicillaire, petit mil [French]; milheto-pérola [Portuguese/Brazil]; mexoeira [Portuguese/Mozambique]; parelgierst [Dutch]; mwele, miwele, mlezi [Swahili]; ثيوم أغبر [Arabic]; બાજરો [Gujarati]; बजड़ी [Hindi]; トウジンビエ [Japanese]; ಸಜ್ಜೆ [Kannada]; ബജ്റ [Malayalam]; बाजरी [Marathi]; aфриканское просо [Russian]; கம்பு [Tamil]; సజ్జలు [Telugu]

Synonyms 

Pennisetum americanum (L.) Leeke, Pennisetum typhoides (Burm. f.) Stapf & CE Hubb, Pennisetum typhoideum Rich., Pennisetum spicatum (L.) Körn., Setaria glauca (L.) P. Beauv. (USDA, 2009)

Description 

Pearl millet (Pennisetum glaucum (L.) R. Br.) is an erect annual grass, reaching up to 3 m high with a profuse root system. Culms are slender, 1-3 cm wide. Leaves are alternate, simple, blade linear, pubescent and minutely serrated, up to 1.5 m long x 8 cm wide. The inflorescence is a panicle, 12 to 30 cm long. Fruits are grains whose shape differs according to cultivars. It uses C4 carbon fixation (Andrews et al., 1992).

Pearl millet grain is considered as a staple food in Africa and India where it is used to make flour, bread, porridge and "couscous" (Ecoport, 2009). As a feedstuff it is mainly grown to produce hay, silage, green-chop, pasture and standover feed grazed directly (FAO, 2009).

Pearl millet stover is the part of the plant that remains after grain harvest and is a fibrous by-product with a low nutritive value. However, dual purpose (grain and forage) varieties with higher forage quality are being developed in South and West Asia (Alexander et al., 2007; Blümmel et al., 2003b). Pearl millet "brown mid-rib" mutants have been used to increase forage quality: they give lower yields but contain less lignin, more crude protein, have higher DM degradability and digestibility, and their overall quality does not drop as quickly as they mature, as occurs with normal mid-rib types (Hassanat, 2007).

Hybrids of pearl millet and Napier grass (Pennisetum purpureum) have been developed. They benefit from the desirable characteristics of pearl millet such as vigor, drought resistance, disease tolerance, forage quality and seed size, whereas Napier grass provides rusticity, aggressiveness, perennity, palatability and high dry matter yield (Timbo et al., 2010).

Distribution 

Pearl millet is native to the Sahel. It has spread across Africa from West to East and from there to Southern Africa. It was introduced to India in 3000 BC and later to America, Brazil and Australia (Andrews et al., 1992). It can be grown between 14 and 32°, N and S, and in every dry tropical area. It thrives well where other C4 cereals (maize, sorghum) cannot grow because of drought or heat. It can be found in regions where annual rainfalls range from 125 to 900 mm. Ideal growth temperatures range from 21°C to 35°C. Pearl millet is known to tolerate acid sandy soils and is able to grow on saline soils (FAO, 2009).

Forage management 

Yield

Dry matter yields of pearl millet forage vary greatly depending on environmental conditions (soil fertility, soil moisture, temperature) and varieties. In semi-arid environments, DM yields can be as low as 0.25-3 t/ha, while under ideal conditions they can reach 27 t/ha and even more than 40 t/ha. However, yields are often about 20 t/ha in the tropics, and 8-10 t/ha in the subtropics (Cook et al., 2005).

Pasture

Pasture can be grazed 40-50 days after seeding, when it is about 40-50 cm high, but it should not be grazed below 15-30 cm (Teutsch, 2009; Andrews et al., 1992; Lang, 2001). Regular rotational grazing or mowing is advisable, because it increases the productive season by preventing heading and maintains high nutritive value (Andrews et al., 1992). A rest period of 5 weeks gives better results than a 2-week period. Optimal height of regrowth appears to be between 50 and 86 cm as it yields better compared to shorter or taller heights (Beaty et al., 1965).

Hay

Pearl millet intended for hay should be cut at the boot stage. A 3-4-week cutting interval is advisable and 2-3 cuts can be taken during the warm season (Teutsch, 2009; Lang, 2001). Stand management should promote extensive tillering in order to reduce culm thickness. This is possible with a high seeding rate. Pearl millet can be ensiled at the soft dough stage (Newman et al., 2006).

Silage

Pearl millet should be cut from boot to soft dough stage rather than at the vegetative stage as it makes more stable silage (Hassanat, 2007). Pearl millet silage has proved itself the equal of maize silage when cut at 8 to 12 weeks (full flowering): the best time would be three weeks after flowering, when its dry-matter yield compares favourably with maize (FAO, 2009). There are many ways to ensile pearl millet forage: it can be ensiled alone (taking the whole plant or only tillers or leaves), or mixed with other grass or legume (Amodu et al., 2005; Tielkes et al., 1998). Pearl millet is reported to yield better than other silages crops in South Africa (Andrews et al., 1992).

Pearl millet silage is prone to lose 13% to 23% of its dry matter and up to 50% of the crude protein (Amodu et al., 2005; Tielkes et al., 1998). The protein of pearl millet forage is very soluble and, during ensiling, almost 50% of the crude protein was degraded into non-protein N due to extensive proteolysis (Guimaraes et al., 2010; Hassanat, 2007). It is advisable to pre-wilt and chop green material before ensiling pearl millet in order to prevent those losses (Amodu et al., 2005). Silage inoculation with homo-fermentative lactic acid bacteria is not necessary and even unadvisable as it does not avoid protein losses and decreases the aerobic stability of the silage (Hassanat, 2007). Pearl millet silage (soft dough grain stage) has a higher pH and lower lactic acid content than corn silage (Hill et al., 1999). Its overall nutritive value may vary according to the variety of pearl millet (Guimaraes et al., 2010).

Environmental impact 

Pearl millet is able to thrive in high salinity soils, where it maintains its good nutritive value. It can be used to increase the economic value of marginal saline soils in Egypt (Fahmy et al., 2010).

Nutritional aspects
Nutritional attributes 

Pearl millet is palatable to livestock but its nutritive value depends on variety, growing conditions, stand management and preservation methods.

Several varieties have been developed in order to enhance forage yield, palatability and digestibility. Breeding programs have created shorter varieties (half the height of natural pearl millet) with a higher nutritive value because the dwarf trait increases the leaf:stem ratio and subsequently crude protein. In brown mid-rib varieties the lignin content is much lower than in normal pearl millet, in vitro DM digestibility is thus enhanced (Andrews et al., 1992). Pearl millet is able to grow in scarce conditions (irrigation with high level of water salinity) without losing nutritive value (Fahmy et al., 2010).

The crude protein content of green pearl millet forage varies from 6 to 20%. The fresh forage is fairly well digested by ruminants, with DMD being about 66-69%. In pearl millet silage, crude protein content is low (from 4% to 10%) due to protein losses, and the rumen degradable fibre fraction is low (Guimaraes et al., 2010).

The nutritive value of pearl millet stover depends on chemical composition and in vitro OMD (ranging between 40% and 60%), and also on simple morphological traits such as culm diameter (the greater the diameter, the less digestible the stover) (Alexander et al., 2007).

Pearl millet stalks have a low nutritive value that can be improved with urea treatment, which increases nitrogen content, DM intake and digestibility (Choudhary et al., 2004; Ramana et al., 1989).

Potential constraints 

Nitrate poisoning

Nitrates are generally non toxic to ruminants but their transformation into ammonia in the rumen produces toxic nitrites that bind with haemoglobin and prevent blood from binding with oxygen, resulting in oxygen starvation of the tissues and animal death in the most severe cases (Marais, 2001). Nitrate levels ranging from 0.5% DM to 1% in the plants are considered potentially toxic to ruminants while levels higher than 1% DM are considered dangerous (Yaremcio, 1991).

Levels of nitrate ranging from 0.24 to 0.98% have been reported in pearl millet (Krejsa et al., 1984). Grazing pearl millet can potentially cause nitrate poisoning, and above 0.6% nitrate reduced milk yield in dairy cattle (Newman et al., 2006). High nitrate levels can happen under drought (Sedivec et al., 1991) or after heavy applications of nitrogen fertilizer (FAO, 2009). A period of four to six weeks of growth is recommended before grazing since young pearl millet plants may have nitrate levels toxic to livestock (Sedivec et al., 1991). Recommended grazing height above 30-40 cm normally guarantees low levels of nitrate since nitrates are mainly concentrated in the lower parts of the stems (below 15 cm) (Lang, 2001). Making hay does not reduce nitrate levels but ensiling can result in a 40 to 60% nitrate reduction (Newman et al., 2006).

Alkaloids

Some pearl millet varieties contain alkaloids at levels ranging from 17 to 101 mg kg-1 (Krejsa et al., 1984). Water stress as well as added N fertilizer appear to increase nitrate and alkaloid contents. Non-drought-stressed forage was found to contain 1% nitrate and 10 to 20 mg/kg alkaloids, while drought-stressed forage had 3% nitrate and 180 to 460 mg/kg alkaloids (Krejsa et al., 1984; Rouquette et al., 1980). Supplying water to pearl millet during dry periods decreases its alkaloid content. Under extreme drought stress conditions, palatability and total consumption were negatively altered as total alkaloids and nitrate content increased (Rouquette et al., 1980).

Oxalic acid

Oxalic acid acts as an antimetabolite, interfering with protein metabolism and thereby reducing the quality of pearl millet forage (Rachie et al., 1980). High levels of oxalic acid were found in twigs, and weight losses were observed when they were offered as sole forage (Verma et al., 2004). Oxalic acid, combined with high K, Mn and Na content is suspected to have a deleterious effect on the milk fat content of cows’ milk (Andrews et al., 1992). Limiting K fertilizer and correcting Ca and Mg deficiencies appear to reduce oxalate content while increasing milk butterfat (Schneider et al., 1970 cited by Andrews et al., 1992). Soaking pearl millet forage before feeding dairy cows also decreases oxalate toxicity (Parveen et al., 1988 cited by Andrews et al., 1992).

Other feeding risks

Pearl millet forage contains HCN but not enough to be hazardous to stock, including horses, and does not contain tannins (Newman et al., 2006). Rust diseases in pearl millet result in decreased nutritive value for livestock. Rust-resistant varieties have been developed to solve this problem (Andrews et al., 1992).

Ruminants 

Pearl millet is a valuable forage for ruminants, it is palatable and digestible. There are very few toxicological concerns with pearl millet even when grown under scarce conditions.

The table below sums up some nutritive characteristics (DM intake and digestibility) of green grass, hay and stover of regular and selected varieties of pearl millet fed to ruminants:

Material Animal Intake Digestibility References
Green        
Normal green forage Sheep   66.6% in vitro DMD Cherney et al., 1990a
Brown mid-rib forage Sheep   69.1% in vitro DMD Cherney et al., 1990a
Hay        
Hay harvested at boot stage   22 g OM/kg LW 73.9% OMD Cherney et al., 1990b
Brown mid-rib hay Sheep (44.4 kg) 23 g DM/kg LW 66.7% DMD Cherney et al., 1990a
Normal Sheep (44.4 kg) 23 g DM/kg LW 64.4% DMD Cherney et al., 1990a
Silage        
Pearl millet silage Sheep 23.1 g DM /kg LW0.75 60% DMD Pinto et al., 1999
Stover and straw        
Stover (stalks+leaves), low fertilizer levels Bulls (262 kg) 34.9-44.4 g OM/kg LW0.75 45.3-51.3% OMD Blümmel et al., 2003a
Stover (stalks+leaves), high fertilizer levels Bulls (262 kg) 41.3-49.3 g OM/kg LW0.75 40.1-48.1% OMD Blümmel et al., 2003a
Stover Sheep (males, 20kg) 36.9-59.6 g OM/kg LW0.75 47.7-60.1% OMD Alexander et al., 2007
Straw Sheep (27 kg) 35 g DM/kg LW0.75 43.6% DMD Nantoumé et al., 2000
Stover leaves Sheep (40 kg) 53.5 g DM/kg LW0.75   Fernandez Rivera et al., 1994

Dairy cows

Pasture

Pearl millet pasture is palatable to cows who prefer young leaves to older ones (Ball, 1903). It can sustain high stocking rates (4.7-6.7 cows/ha), medium to high milk yield (19.8 kg/day) and lower weight losses compared to sudangrass or sorghum x sudangrass hybrid over a three-year period (Clark et al., 1965). It can sustain 13 to 15 kg milk/day/cow without supplementation during the pre-dry season (Benedetti, 1999).

Pearl millet cultivated under a warm climate contained enough metabolizable protein to meet the needs of high yielding dairy cows (600 kg LW, 30 litres milk/day/cow) if they ate 11.6 kg DM/day. However, pearl millet forage may not meet the energy requirements of lactating dairy cows (Fulkerson et al., 2008). High yielding dairy cows grazing a mixed pasture of pearl millet forage and cowpea had higher intake and milk yield when they were supplemented, however the economic return was greater with no supplementation (Hanisch et al., 2005).

A significant depression of milk butterfat occurred in cows grazing pearl millet forage (see Potential constraints above) (Clark et al., 1965).

Silage

Pearl millet silage may be included at 50% (DM basis) in a lucerne silage/concentrate-based diet, or 36% (DM basis) of a concentrate-based diet, and sustain 24-26.3 kg/d milk yield in lactating dairy cows (Kochakpadee et al., 2002; Messman et al., 1991). Milk fat and protein content were 3.6% and 2.8% respectively (Kochakpadee et al., 2002). Pearl millet silage (38.5% DM, 15% CP) offered to 325 kg dairy heifers was eaten at 2.4% of body weight on DM basis and the DM digestibility was 64.3% (Jaster et al., 1985).

Growing and fattening cattle

Pasture

Weanling beef heifers reared on pearl millet pasture in a continuous grazing system had to be supplemented with a high-energy concentrate feed (corn grain or dried citrus pulp or soyhulls) at 0.9% of the body weight in order to support growth requirements and normal first mating at 18-24 months (Santos et al., 2005). In older beef heifers (15 months, 250 kg), providing pearl millet forage yielding 1125-1770 kg DM/ha over 3 months resulted in a 14-15 kg forage DM intake and sustained a growth rate of 800 g/d; an earlier mating age (18-20 months) was then possible (Montagner et al., 2009). Pearl millet pasture, either unfertilized or fertilized (0,150 or 300 N kg/ha) supported daily live-weight gains of 553 g (unfertilized) to 764 g/d (300 kg N/ha) in 13-14 month steers weighing 230 kg (Moojen et al., 1999).

Cut-and-carry system

In Mali, pearl millet green leaves are collected 65 to 85 days after sowing, before grain harvest, and are fed fresh to draught cattle. Earless tillers which bear no grains can be collected as early as 45-65 days after sowing; they provide early season fodder. Green leaves and earless tillers meet recommendations for crude protein and metabolizable energy for 300 kg beef cattle fed rice straw ad libitum (Tielkes et al., 1998).

Silage

Pearl millet silage fed to fattening steers at 84% (DM basis) plus 16% concentrate for 6 months resulted in decreasing average daily weight gain from 710 g/day for the first 2 months, 400 g/day during the next two months and 200 g/day during the last 2 months (Bolsen et al., 1980).

Pearl milllet silage did not compare favourably with maize silage: it resulted in lower DM intake (2.9 kg vs7 kg) and lower average daily weight gain (150-200 g/day vs950g/day) in growing heifers. Even when pearl millet silage was inoculated and supplemented with 0.5% ground maize, steers had a lower daily weight gain than with maize silage (770 g/day vs1220 g/day) (Hill et al., 1999).

Sheep

Pasture

Pearl millet is a valuable pasture for sheep. During a period of strong drought, pearl millet pasture was able to support higher stocking rates than regular or improved native grassland (914 kg LW/ha vs. 261 and 467 kg LW/ha respectively) and resulted in higher daily weight gains (151 g/d vs. 53 and 58g/d respectively) (Brum et al., 2008).

Pearl millet can be sown with Lablab purpureus, which provides crude protein supplementation. The association compares favourably with other grass/legume combinations and results in 120 g of daily weight gain in sheep grazing the stand (Aganga et al., 2000). Supplementing sheep fed on a pearl millet forage basal diet with crude protein sources such as cassava meal, corn gluten feed or with commercial concentrate results in greater animal performance:

  • 133 g daily weight gain on pearl millet + corn gluten feed were observed, vs. 72 g daily weight gain on pearl millet alone (Jochims et al., 2010);
  • 96 g daily weight gain on pearl millet + commercial concentrate (19.8% CP) vs. 54 g daily weight gain on pearl millet alone (Elejalde et al., 2010);
  • 110-120 g daily weight gain on pearl millet + commercial concentrate (21.8% CP) (Camargo et al., 2009).

Recommended levels of supplementation range from 0.5% to 1.5% body weight (Jochims et al., 2010; Elejalde et al., 2010; Camargo et al., 2009). Daily weight gain is more sensitive to supplementation and positively correlated when pasture quality decreases (Camargo et al., 2009).

Silage

In sheep, pearl millet silage was not as readily eaten as stover (see Nutritional attributes above) but its digestibility was similar (Pinto et al., 1999). In order to increase crude protein content and cell wall digestibility, pearl millet can be ensiled with cowpea (Silveira et al., 1981). However, this mixture did not sustain animal requirements and some supplementation (in energy and protein) was needed (Singh et al., 1980).

Straw

Pearl millet straw can be fed to sheep. Urea treatment enhances its palatability and total digestible nutrients (Choudhary et al., 2004). Straw ammoniation (4%) is advisable as it enhances DM intake, crude protein and crude fibre digestibility by more than 10% in a pearl millet straw/concentrate-based diet (Ramana et al., 1989). Treating millet straw with a 5% urea solution increased DM digestibility by 23%, DM intake by 16% (from 42.6 to 49.2 g/kg W0.75) and average daily gain by 12% (from 41 to 51 g/kg) in Djallonké rams (Mattoni et al., 2007).

Goats

Pearl millet forage can be fed to goats. It results in similar DM, OM and NDF intakes as Sudan grass, elephant grass or forage sorghum. The crude protein intake and digestibility of pearl millet forage are higher than for other forages in goats (Aguiar et al., 2006). Pearl millet hay replaced clover hay without altering the reproduction of female goats and the performance of the kids (Hanafy et al., 2007).

Rabbits 

No information found (2011).

Horses and donkeys 

Because of its low HCN content, pearl millet forage can be safely fed to horses under rotational grazing (Sedivec et al., 1993).

Nutritional tables

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 19.4 4.2 14.1 28.5 17  
Crude protein % DM 12.4 2.9 6.6 17.0 19  
Crude fibre % DM 29.2 4.8 21.1 39.7 19  
NDF % DM 64.8 8.8 46.1 64.8 4 *
ADF % DM 34.5 8.0 30.7 45.1 3 *
Lignin % DM 4.2         *
Ether extract % DM 2.0 0.5 1.4 3.0 18  
Ash % DM 12.3 2.0 9.2 15.8 17  
Water-soluble carbohydrates % DM 2.7       1  
Gross energy MJ/kg DM 17.6         *
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 5.5 2.3 2.9 8.5 8  
Phosphorus g/kg DM 2.8 1.3 0.4 4.5 8  
Potassium g/kg DM 31.5 11.0 16.0 41.9 6  
Magnesium g/kg DM 3.2 0.8 2.4 4.5 6  
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, Ruminant % 68.5 1.7 68.5 75.2 8 *
Energy digestibility, ruminants % 65.5         *
DE ruminants MJ/kg DM 11.5         *
ME ruminants MJ/kg DM 9.2         *
Nitrogen digestibility, ruminants % 64.1 8.1 51.5 72.3 8  
a (N) % 36.5   30.0 43.0 2  
b (N) % 48.5   48.0 48.9 2  
c (N) h-1 0.034   0.030 0.038 2  
Nitrogen degradability (effective, k=4%) % 59         *
Nitrogen degradability (effective, k=6%) % 54   46 62 2 *

The asterisk * indicates that the average value was obtained by an equation.

References

Aguiar et al., 2006; CIRAD, 1991; French, 1943; Fulkerson et al., 2008; Patel, 1966; Prado et al., 2004; Sen, 1938; Van Wyk et al., 1951; Zaharaby et al., 2001

Last updated on 02/05/2013 17:22:31

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 90.1 89.6 90.6 2
Crude protein % DM 9.6 2.0 6.6 10.9 4
Crude fibre % DM 41.2 1
NDF % DM 76.0 2.0 66.5 76.0 3 *
ADF % DM 47.7 2.3 44.0 48.5 3 *
Lignin % DM 7.1 0.9 5.9 7.6 3 *
Ether extract % DM 1.4 0.1 1.3 1.4 3
Ash % DM 10.7 0.6 10.0 11.4 4
Gross energy MJ/kg DM 18.0 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 3.7 1
Phosphorus g/kg DM 4.2 1
Potassium g/kg DM 39.4 1
Magnesium g/kg DM 2.3 1
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 52.7 52.7 60.2 2 *
Energy digestibility, ruminants % 49.4 *
DE ruminants MJ/kg DM 8.9 *
ME ruminants MJ/kg DM 7.1 *
Nitrogen digestibility, ruminants % 46.0 32.9 59.1 2

The asterisk * indicates that the average value was obtained by an equation.

References

Aguiar et al., 2006; Aguiar et al., 2006; Arieli et al., 1989; Van Wyk et al., 1951

Last updated on 24/10/2012 00:44:46

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 93.1 0.7 92.2 94.5 19
Crude protein % DM 5.2 1.2 3.0 6.6 20
Crude fibre % DM 41.8 1.5 37.9 43.6 17
NDF % DM 80.0 2.1 76.3 83.5 17
ADF % DM 52.9 3.7 42.9 57.2 19
Lignin % DM 10.7 1.3 8.3 13.2 18
Ether extract % DM 0.7 0.2 0.4 1.1 18
Ash % DM 8.6 1.4 5.9 11.4 21
Gross energy MJ/kg DM 17.7 0.6 17.7 19.2 5 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 2.5 1.1 1.0 5.7 18
Phosphorus g/kg DM 1.5 0.6 0.7 3.2 18
Potassium g/kg DM 23.8 6.6 12.7 43.6 18
Sodium g/kg DM 0.2 0.0 0.1 0.3 9
Magnesium g/kg DM 3.8 1.2 1.7 5.9 19
Manganese mg/kg DM 96 33 43 141 9
Zinc mg/kg DM 26 8 15 36 10
Copper mg/kg DM 7 4 4 16 10
Iron mg/kg DM 667 1
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 47.4 6.5 38.0 52.8 4
Energy digestibility, ruminants % 43.7 *
DE ruminants MJ/kg DM 7.7 *
ME ruminants MJ/kg DM 6.3 *
Nitrogen digestibility, ruminants % 7.0 1.0 12.9 2

The asterisk * indicates that the average value was obtained by an equation.

References

Bennison et al., 1998; CIRAD, 1991; French, 1943; Gowda et al., 2004; Ncube et al., 1992; Richard et al., 1989; Sen, 1938

Last updated on 24/10/2012 00:44:46

References
References 
Datasheet citation 

Heuzé V., Tran G., Hassoun P., Sauvant D., 2015. Pearl millet (Pennisetum glaucum), forage. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/399 Last updated on September 30, 2015, 14:02

English correction by Tim Smith (Animal Science consultant) and Hélène Thiollet (AFZ)
Image credits