Effects of agroindustrial by-product supplementation on dairy goat milk characteristics, nutrient utilization, ruminal fermentation, and methane production.

The use of agroindustrial by-products, such as dried distillers grains with solubles (DDGS) and dried citrus pulp (DCP), has been widely investigated in dairy cows, but information on their effects in dairy goats is limited. The influence of feeding olive cake (a by-product of olive oil production) to dairy goats has been assessed in some studies, but exhausted olive cake (EOC) has been much less investigated. Twelve Murciano-Granadina goats were used in a crossover design trial with 2 periods to assess the effects of including agroindustrial by-products on nutrient digestibility, ruminal fermentation, methane production, urinary excretion of purine derivatives, and milk yield and composition. In each period, 6 goats received daily a control diet comprising 1 kg of alfalfa hay and 1 kg of high-cereal concentrate, and another 6 goats received a diet (BYP) comprising 1 kg of alfalfa hay and 1 kg of a concentrate including corn DDGS, DCP, and EOC in proportions of 180, 180, and 80 g/kg of concentrate (as-fed basis), respectively. Diet had no effect on total dry matter intake, but intake of alfalfa hay, CP, and fat was greater for the BYP group than for the control group. There were no differences between diets in nutrient apparent digestibility, with the exception of fat, which was greater for the BYP diet compared with the control diet. Although fecal N tended to be greater for the BYP diet, there were no differences in N utilization. Compared with the control diet, milk yield tended to be greater and daily production of milk CP, fat, whey protein, and TS as well as milk gross energy were greater for the BYP diet. The concentration of C12:0, C14:0, and C16:0 fatty acids (FA) was or tended to be lower and the concentration of polyunsaturated FA was greater in the milk of BYP-fed goats compared with goats fed the control diet. Diet had no effect on ruminal parameters (pH, volatile FA, and NH3-N concentrations) and methane emissions, but urinary excretion of total purine derivatives tended to be lower in BYP-fed goats than in those fed the control diet. A mixture of corn DDGS (180 g), DCP (180 g), and EOC (80 g) could replace 44% of cereal grains and protein feeds in the concentrate for dairy goats without compromising nutrient utilization, ruminal fermentation, or milk yield and led to a more unsaturated FA profile in milk.

Can by-products replace conventional ingredients in concentrate of dairy goat diet?

Intensive dairy goat production in the Mediterranean basin is based on imported conventional ingredients to be included in concentrates. Fourteen Murciano-Granadina goats in the middle of the third lactation were allocated into 2 groups of 7 animals each fed, respectively, a control diet based on alfalfa hay and concentrate in a 40:60 ratio, and a diet in which the concentrate included tomato fruits, citrus pulp, brewer's grain and brewer's yeast (T100CBY) to study the effect of diet on nutrient utilization, ruminal fermentation, purine derivatives excretion in urine, milk yield and composition, and methane emissions. No effect of the diet on total dry matter intake was observed. Digestibility of neutral detergent fiber and acid detergent fiber were higher for T100CBY compared with the control diet. The N in feces and urine was lower and balance and retained N were higher in animals fed T100CBY than the control diet. Milk protein N and energy were similar for both diets. Metabolizable energy per energy intake and metabolizable energy per digestible energy were higher and energy in methane was lower with diet T100CBY than with the control. Milk yield and composition were not affected by diet, with the exception of protein, casein, and total solids, which were higher for diet T100CBY than the control. Diet T100CBY promoted less saturated fatty acids and higher mono- and polyunsaturated fatty acids in milk than the control diet. Diet T100CBY produced less methane and NH3 concentration in the rumen, higher propionate, and a lower acetate-to-propionate ratio without an effect on the volatile fatty acid concentration. The concentrate with by-products did not affect urinary excretion of total purine derivatives, reduced feeding costs, and increased profit margin by 14 and 16% compared with the control. The mixture of tomato fruits, citrus pulp, brewer's grain, and brewer's yeast could replace 47% of conventional ingredients (corn, wheat bran, sunflower meal, and soy flour) in the concentrate of the dairy goat diet, reducing feeding cost and methane production, leading to a healthier fatty acids profile in milk without compromising nutrient utilization or milk yield.

Nutrient utilization, ruminal fermentation, microbial nitrogen flow, microbial abundances, and methane emissions in goats fed diets including tomato and cucumber waste fruits.

The effects of replacing 50% of cereals-based concentrate with feed blocks (FB) including wastes of tomato fruits (diet ACT), wastes of cucumber fruits (diet ACC), or barley grain (diet ACB) on nutrient use, ruminal fermentation, microbial N flow to the duodenum, methane emissions, and abundances of total bacteria and methanogen were studied in goats. Four adult, dry, nonpregnant, rumen-fistulated Granadina goats (32.1 ± 5.52 kg BW) were used and 4 diets were studied in 4 trials by using a 4 × 4 Latin square experimental design. Diets consisted of alfalfa hay plus concentrate in a 1:1 ratio (AC) or 1:0.5 plus FB including wastes of ACT, ACC, or ACB. In each trial, goats were randomly assigned to 1 of the diets. Intake of each FB including ACT, ACC, and ACB were 203 ± 73, 179 ± 39, and 144 ± 68 g·animal(-1)·d(-1), respectively. The ACT and ACC diets did not (P > 0.05) compromise digestible and metabolizable energy, but reduced N retention by up to 29% (P = 0.03). Cucumber-based FB decreased the purine bases (PB):N ratio (P = 0.02) in total bacterial pellets isolated from the rumen content. Tomato-based FB decreased purine derivatives urinary excretion (P = 0.04) and microbial N flow (P = 0.03) without affecting the efficiency of synthesis but decreased methane emission by 28% (P < 0.001) compared with the other diets. Tomato and cucumber-based FB resulted in greater (P < 0.001) rumen VFA concentration and molar proportions of propionate and butyrate (P ≤ 0.02) than AC and ACB diets. No effect (P = 0.07) of diet on total bacteria abundance was observed whereas the abundance of methanogens increased (P = 0.01) with wastes-based FB. Our study suggests that ACC-based FB could replace one-half of the amount of concentrate in goat diet without compromising rumen fermentation and nutrient and energy use and without increasing methane emissions. Blocks including ACT showed an antimethanogenic effect but reduced microbial N flow to the duodenum. Further research is needed to improve both N and energy use of diets including ACT- and ACC-based FB.

Nutrient utilization, ruminal fermentation, microbial abundances, and milk yield and composition in dairy goats fed diets including tomato and cucumber waste fruits.

The effects of replacing 35% of cereals-based concentrate with feed blocks (FB) containing waste fruits of tomato, cucumber, or barley grain in diets for lactating goats on nutrient utilization, ruminal fermentation, microbial N flow to the duodenum, milk yield and quality, methane emissions, and abundances of total bacteria and methanogens were studied. Eight Murciano-Granadina goats (39.4 ± 5.39 kg of body weight, mean ± SD) in the middle of the third lactation were used and 4 diets were studied in a replicated 4×4 Latin square experimental design. Diets consisted of alfalfa hay (A) plus concentrate (C) in a 1:1 ratio (diet AC) or diets in which 35% of the concentrate was replaced with FB including wastes of tomato fruit, cucumber, or barley. In each period, 2 goats were randomly assigned to 1 of the dietary treatments. Intakes of FB including tomato, cucumber, and barley were 208 ± 65, 222 ± 52, and 209 ± 83 g of dry matter per animal and day, respectively. The replacement of 35% of concentrate with FB did not compromise nutrient apparent digestibility, total purine derivative urinary excretion, milk yield and composition, and total bacteria and methanogen abundances. Digestible energy and that in methane and urine were higher for AC than for FB-containing diets, whereas the metabolizable energy value was not affected by diet. The inclusion of tomato and cucumber fruits in FB decreased N in urine and CH(4) emissions compared with AC, which is environmentally relevant. However, tomato-based FB decreased microbial N flow in the rumen, whereas goats fed cucumber-based FB had the highest values for this measurement. Moreover, FB containing barley or tomato and cucumber led to lower rumen volatile fatty acid and NH(3)-N concentrations, respectively. Milk from goats fed diets including tomato and cucumber-based FB had higher linoleic, linolenic, and total polyunsaturated fatty acid concentrations than that from goats fed AC. Overall, our study suggests that tomato and cucumber FB could replace 35% of the concentrate in the dairy goat diet, reducing animal feeding cost and methane production, leading to higher polyunsaturated fatty acid proportions in milk, and without compromising nutrient utilization or milk yield.