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California is the leading state for the production of almonds, with more than 400,000 bearing hectares of orchards that produced approximately 1 billion kg of shelled nuts in 2017. Almond hulls (AH) are a regional by-product feedstuff fed predominately to dairy cattle in California. A 2012 study surveyed 40 dairy farms in California and found that 39 out of 104 total mixed rations contained AH, with a mean daily feeding rate of 1.45 kg/cow. In 2017, approximately 2 billion kg of AH was produced. At a feeding rate of 1.45 kg/cow daily, even if all 1.7 million lactating cows in California are consuming AH, there will be a surplus of AH on the market as the approximately 130,000 nonbearing hectares come into nut production. Therefore, the potential of feeding varying amounts of AH to lactating dairy cows was investigated using 12 Holstein cows with 4 primiparous and 8 multiparous cows. The dietary treatments were 4 total mixed rations containing 0, 7, 13, or 20% AH. The AH used contained 12.8% crude fiber (as-is basis), which was below the 15% legal limit set by state feed regulations. Diets were formulated so that as the inclusion rate of AH increased, the amount of steam-flaked corn and soyhull pellets decreased and soybean meal inclusion increased. Experimental design was a replicated 4 × 4 Latin square. Diet had a cubic effect on actual milk yield, energy-corrected milk yield, and dry matter intake, with the 7% AH diet having the highest values and the 13% AH diet having the lowest. The percent and yield of total solids and the yields of lactose and fat did not differ with diet, but percent and yield of protein declined linearly with increased AH inclusion, and fat percent increased linearly. Apparent total-tract digestibilities of dry matter and organic matter were higher with the inclusion of AH in the diet. Total percentage of the day spent ruminating increased linearly with higher amounts of AH. Overall, this work demonstrated that AH can be fed at vary-ing amounts, up to 20% of the diet, to lactating dairy cows to support high levels of milk production and that increasing amounts of AH (up to 20%) in the diet could lead to improved digestibility and milk fat percentage but decreased milk protein production.

Whole tomato seeds, a novel by-product feedstuff, were fed to lactating Holstein cows to determine the nutritive value of whole tomato seeds by replacing whole cottonseed in the total mixed ration. Four primiparous and 4 multiparous Holstein cows were used in a 4×4 Latin square design and fed 1 of 4 total mixed rations. Whole tomato seeds replaced whole cottonseed on a weight-to-weight basis for lipid. The proportion of whole tomato seeds to whole cottonseed in the diets were 100:0, 50:50, 25:75, and 0:100 on a lipid basis. Thus, tomato seeds were 4.0, 2.4, 1.1, and 0% of the ration dry matter, respectively. Milk yield and the concentrations and yields of protein, lactose, and solids-not-fat did not differ for the effect of diet. However, milk fat concentration decreased and milk fat yield tended to decrease as whole tomato seeds replaced whole cottonseed. Intakes of dry matter, lipid, and crude protein did not differ. Whole-tract apparent digestibility of dry matter and ash-free neutral detergent fiber did not differ, but digestibility of total fatty acids and crude protein decreased with increasing proportion of whole tomato seeds. Urea concentration in milk and plasma both decreased with increasing whole tomato seeds. Fecal concentration of linoleic and α-linolenic acids increased with increasing whole tomato seeds, suggesting that seeds were passing out of the digestive tract undigested. The concentrations of C18:2n-6 and C18:3n-3 in milk fat had small increases, but their yields were not different, suggesting that only a small amount of whole-tomato-seed lipid might have been digested postruminally. Amounts of trans C18:1 fatty acids in milk fat were higher with increasing whole cottonseed, which might suggest a shift in rumen biohydrogenation pathways. At the level of feeding used in the current study, whole tomato seeds replaced whole cottonseed in the diet of lactating dairy cows without a change in production.

The aim of this study was to determine the in vitro digestibility and in sacco disappearance of dry matter (DM) and neutral detergent fibre (NDF) in total almond hulls (TAH), pure almond hulls (PAH) or Debris. The TAH were used because there are no data on the effect of debris (non-hull material) on the nutritional value of almond hulls. Twelve samples of commercial almond hulls were used, with one subsample representing the TAH and the other subsample hand sorted to separate the hulls (PAH) from Debris. Gas production and Ankom Daisy method were used to determine in vitro digestibility, while two rumen-fistulated cows were used to measure in sacco disappearance of PAH and TAH. For in vitro digestibility, both PAH and TAH were more digestible and had greater gas production than Debris. The PAH had greater in vitro true digestibility on a DM basis and NDF digestibility at 48 and 72 h compared with TAH. Nonpareil hulls provided greater metabolizable energy (ME) concentration when compared with other almond varieties, with PAH supplying numerically more ME than TAH for both varieties. For in sacco disappearance, PAH had greater DM and NDF disappearance along with a greater rate of disappearance for NDF compared with TAH. This research demonstrated that Debris is highly indigestible; therefore, hulling, agronomic and harvesting practices should be focused on reducing Debris in commercial almond hulls to improve their nutritive value as a feedstuff for livestock.

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