Apple pomace and whole apples contain high amounts of sugars (mainly fructose and glucose) and are, therefore, a good source of rapidly digestible energy in the rumen (Gullon et al., 2007; Kolodziejczyk et al., 2007). Because of its low nitrogen content and intake level when fed alone, apple pomace (fresh, dried or ensiled) must be supplemented with a good protein source and fibrous material such as straw. It is not recommended to use it alone.
Palatability
Apple pomace and culled apples are palatable to ruminants (NRC, 1983; NDDB, 2012). Cattle grazing in apple orchards are fond of picking apples directly from the trees (Tran, personal communication).
Digestibility and degradability
The in vitro DM degradability of fresh apple pomace is high at around 75% (Edwards et al., 1995). In sacco DM degradability (DMD) of fresh apple pomace ranged from 77 to more than 90% after 24h incubation (Anrique et al., 2002; Kafilzadeh et al., 2008 ). After 42 or 48h incubation DMD ranged from 84 to more than 90% (Kafilzadeh et al., 2008; Anrique et al., 2002). Dried and ensiled apple pomace gave similar values with 67-73% after 24h and 82-84% after 42 or 48h (Singh et al., 1992; Anrique et al., 2002). The potential degradability of fresh apple pomace measured with the gas production method showed a rapid degradability with 86% within 24h and 98% after 48h incubation (Tagliapietra et al., 2015). All these measures confirm that apple pomace DM is rapidly degradable, which is explained by its high soluble fraction.
In vivo OM digestibility of apple pomace silage supplemented with nitrogen (soybean meal, alfalfa or urea) when measured on sheep ranged from 70 to 78% (Alibes et al., 1984), which is in agreement with the above in vitro values (Alibes et al., 1984). The in vivo DMD and OMD of dried apple pomace, measured in sheep with only urea as a supplement, was relatively high with 66.8% and 69.9%, respectively (Taasoli et al., 2008). Based on in vitro digestibility estimates, apple pomace could fully replace barley as an energy source in an alfalfa hay based diet (Khatooni et al., 2014).
Figure 1: DM degradability of fresh, ensiled or dried apple pomace measured with the in sacco method (adapted from Singh et al., 1992; Anrique et al., 2002; Kafilzadeh et al., 2008).
Dairy cows
Apple pomace (fresh or as silage) can be introduced at up to 30% in a dairy cow diet fed indoors or at pasture. It increases total DM intake, milk yield and milk composition (see Table 1 below) with no apparent adverse effects.
Beef cattle
Growing cattle
Apple pomace replaced half of maize grain in a diet for steers based on good ryegrass forage (Ribeiro et al., 2012). When offered to 175 kg calves as sole feed, supplemented with only minerals, dried or fresh apple pomace DM intake and digestibility were 1.21 and 1.98% of body weight and 43.8% and 57.8%, respectively (Singhal et al., 1991).
In India, ground and dried apples were incorporated as an energy source at up to 30% of the concentrate mixture of crossbred calves, thereby totally replacing the maize (NDDB, 2012).
Beef cows
Apple pomace silage used as fibrous feed during the gestation of beef cows should be supplemented with a protein supplement rather than with non-protein supplement, as the cows supplemented with non-protein supplements had calves that, although born alive, were lighter, weaker, and had skeletal abnormalities. Besides, calf mortality was increased (Fontenot et al., 1977).
When fresh apple pomace was included at increasing levels (5 to 20% on a DM basis) into a total mixed ration (TMR), prepared as silage and offered to beef cows, the DM and OM digestibility of the TMR tended to decrease from 53 to 51% and from 58 to 55.4%, respectively, with increasing levels of apple pomace (Fang et al., 2016).
Sheep
As observed with cows, fresh or dried apple pomace supplemented with urea did not meet the requirements for gestating ewes. Compared to a control diet, there were more stillbirths, birth weights were lower, lamb survival was poor and there were structural abnormalities. Supplementing apple pomace with a good protein source (soybean meal) and fibrous feed (straw or forage) improved or alleviated these negative effects (Rumsey et al., 1982). Dried or ensiled apple pomace included into a total mixed ration at 20 or 30% allowed a good daily weight gain in fattening lambs and a higher carcass dressing percentage (Taasoli et al., 2008). In sheep, diet DM intake tended to be higher when apple pomace was supplemented with a good quality nitrogen such as alfalfa (55.4 g/kg0.75), rather than with urea (38.7 g/kg0.75) (Alibes et al., 1984).
Table 1. Effects of apple pomace in ruminant diets
Animal |
Breed/physiological stage |
Country |
Experiment |
Rate of apple pomace |
Main results |
Reference |
Dairy cows |
Black Friesian
(early lactation) |
Chile |
Increasing levels of AP in diet based on HS |
0, 20 or 30% |
The higher level of AP increased milk yield (25.4 vs. 23.3 L/d), milk fat (36 vs. 33 g/L) and protein (34 vs. 33 g/L) contents. Increasing levels of AP decreased HS intake but increased total forage intake from 8.2 to 11.2 kg DM/d. |
Anrique et al., 2003 |
|
Friesian-Jersey
(490 kg, 196 days) |
New Zealand |
Pasture + HS or half HS replaced with AP with or without protein concentrate |
limited (3-4 kg DM/d) |
AP increased pasture intake (+0.65 kg DM), milk yield (14.4 vs. 12.1 kg), and milk protein and fat content. |
Edwards et al., 1995 |
|
Holstein
(565 kg, 75 days) |
Iran |
AP silage included in a TMR |
15 or 30% in TMR |
No effect on diet DMI, milk yield and milk composition with 30% AP silage. |
Ghoreishi et al., 2007 |
|
Holstein (640 kg, early lactation) |
Iran |
Silage of AP (57%) and poultry litter (43%) on DM basis, included in a TMR at various levels |
0, 15, 30 or 45% in TMR |
DMI increased or tended to increase with 15 and 30% inclusion. Milk yield increased with 15% AP but not more with the higher levels. |
Azizi et al., 2014 |
Beef cows |
Angus, Herefords, Shorthorns (gestation) |
USA |
AP silage compared to CS with CSM or NPN supplement |
ad libitum |
AP vs. CS with NPN supplement gave lower DMI (12-15 vs. 18-19 kg DM/d), lower weight change (-16 to 2 vs. 14-37), and lower veal birth weight (12-16 kg vs. 28-33 kg). |
Fontenot et al., 1977 |
Steers |
Holstein fattening (219 kg) |
Brazil |
Steers fed ryegrass (16 CP) and supplemented at 0.5% BW with AP, corn grain or 50% AP and 50% CG |
0.5% BW |
AP supplementation did not modify forage DMI (2.2% BW) or DM digestibility of the diet (74%). DMI of AP fed as sole supplement was lower (0.27% BW) than when associated with CG (0.42% BW). |
Ribeiro et al., 2012 |
Sheep |
Sanjabi fattening lambs (38 kg) |
Iran |
Dried AP included into a TMR for finishing and growing lambs compared to control diet (alfalfa hay and barley grain) |
20% in TMR |
DMI was not different, but DWG was higher with AP (192 g/d) than with the control (124 g/d). |
Taasoli et al., 2008 |
|
Sanjabi fattening lambs (25 kg) |
Iran |
Ensiled AP (with 20% sugar beet pulp) included into a TMR and compared to control diet (alfalfa hay and barley grain) |
30% in TMR |
DMI and DWG were higher with ensiled AP diet than with the control with 0.94 kg DM/d and 0.80 kg DM/d, and 200 g/d and 156 g/d, respectively. |
Taasoli et al., 2008 |
AP: apple pomace; CG: corn grain; CS: corn silage; CSM: cottonseed meal; HS: herbage silage; NPN: non-protein nitrogen