The aim of this study was to determine sorghum silage quality from dairy farms (n = 16) located in California’s San Joaquin Valley. Herd size of the participating dairies ranged from 320 to 5,500 lactating dairy cows (median = 2,013). Sorghum fields were characterized by variety as grain (n = 5) or forage (n = 11) type sorghum, and by presence (n = 10) or absence (n = 6) of sugarcane aphid (SCA) infestation during the growing season. Chopped sorghum was ensiled as wedge or pile structures, and in bags. Each silage structure was visited once and sampled from the exposed face for wet chemistry, nutrient and fermentation analyses. Descriptive statistics were calculated using PROC MEANS of SAS, and effect of sorghum type and SCA infestation on forage quality was analyzed by ANOVA using the GLM procedure of SAS. At the time of sample collection, average ensiled time was 238 d (range = 99–439 d). Nutrient composition of the 16 samples of fermented sorghum silage is presented in Table 1. No differences in key nutritional criteria were found between grain and forage type sorghum. In addition, there was no effect of SCA infestation on parameters of nutritional quality. Sorghum silage pH mean was 3.95 (range = 3.68–4.27). Lactic acid averaged 7.5% (range = 3.5–9.8%), acetic acid averaged 4.0% (range = 1.6–6.6%), and propionic acid averaged 0.03% (range = 0.0–0.3%); butyric acid (mean = 0.1%) was only detected in 3 samples and ranged from 0.0 to 1.3%. The current data set is small and highly variable. There is a need to improve sorghum silage quality and determine best management practices, as sorghum may replace corn as an agronomic crop in areas of California in years of water shortages. Table 1. Sorghum silage nutrient composition (n = 16) in California’s San Joaquin Valley

Item		% of DM						NDFD30,% of NDF
DM	CP	ADF	NDF	Starch	NFC	Ash
Mean	27.9	9.7	34.0	48.7	8.0	26.3	13.2	30.1
Median	27.6	9.5	34.2	49.1	6.9	26.5	12.9	29.9
Minimum	22.4	5.9	29.7	44.7	0.3	19.1	10.3	26.9
Maximum	35.2	12.8	39.2	55.9	18.7	34.3	16.9	34.9
SD	3.5	1.7	2.2	3.2	5.4	4.8	2.1	2.4