Full-fat corn germ in diets for dairy cows as an alternative to ground corn.

The experiments reported in this research paper address the effects of replacing ground corn (GC) with full-fat corn germ (FFCG) on nutrient intake and digestibility, nitrogen utilization efficiency, performance, and predicted methane production in dairy cows fed cactus cladodes and sugarcane. We hypothesized that the inclusion of FFCG in the diet would not alter the performance of lactating cows but would reduce the predicted methane production in vivo. Ten multiparous Holstein cows at 90 ± 10 d of lactation and yielding 24.2 ± 3.5 kg milk/d were assigned to dietary treatments consisting of different levels of replacement of GC by FFCG (0; 25; 50; 75 and 100% of diet dry matter) in a replicated 5 × 5 Latin square design with 21-d periods. Methane production was predicted using an automated gas in vitro production system. Except for ether extract intake, which increased, the intake of all nutrients decreased linearly with the replacement of GC by FFCG. The digestibility of dry matter, organic matter and neutral detergent fiber reduced, whereas the digestibility of ether extract increased linearly with FFCG. There were no changes in the digestibility of crude protein. The nitrogen intake and daily excretion in urine and feces decreased, while nitrogen use efficiency increased linearly. There was no significant effect of diets on nitrogen balance or microbial protein synthesis and efficiency. The yield of protein, lactose and total solids in milk showed a quadratic behavior. On the other hand, milk fat yield and energy-corrected milk yield decreased linearly with the replacement of GC by FFCG. No effect on pH or ammonia nitrogen was observed. The production of methane (CH4, g/kg DM) and total CH4 (g/d), and CH4 intensity decreased linearly with the replacement of GC by FFCG. In conclusion, FFCG has been shown to be an effective source of fat to reduce methane production in dairy cows, partially supporting our initial hypothesis. However, as it decreases milk fat production, it is not recommended to replace more than 50% of GC by FFCG for lactating cows fed cactus cladodes and sugarcane.

Partially replacing sorghum silage with cactus (Opuntia stricta) cladodes in a soybean oil-supplemented diet markedly increases trans-11 18:1, cis-9, trans-11 CLA and 18:2 n-6 contents in cow milk.

Based on low 18:0 contents observed in milk fat of cows fed cactus cladodes (CC), we hypothesized that including Opuntia stricta cladodes in a soybean oil (SO)-supplemented diet would promote incomplete rumen biohydrogenation of supplemental PUFA, leading to increased trans-11 18:1 and cis-9, trans-11 CLA contents in milk. Twelve Holstein cows were used in a two-period study: (a) Baseline: all cows received a total mixed ration (TMR) composed of sorghum silage (SS) and a concentrate containing no SO for 14 days; (b) Treatment: cows received one of the following SO-supplemented diets for 21 days: (1) SS-TMR: a TMR composed of SS and a SO-enriched concentrate, (2) CC-TMR: a TMR containing CC as a partial substitute for SS plus the SO-enriched concentrate, and (3) CC-PMR: same diet as in treatment 2, but CC were mixed with the SO-enriched concentrate and fed as a partial mixed ration (PMR). Both CC diets increased relative abundances of trans-11 18:1, cis-9, trans-11 CLA, and 18:2 n-6 in milk fat, whereas opposite effects were observed on 18:0 and cis-9 18:1. Proportion of 18:2 n-6 increased, and cis-9, trans-11 CLA tended to increase with CC-PMR as compared to CC-TMR, whereas 18:3 n-3 was higher with CC-PMR than with SS-TMR. Proportions of several odd- and branched-chain fatty acids, certain 18:1 isomers, and trans-9, cis-11 CLA changed with CC diets, notably with CC-PMR. Milk yield and intake of most nutrients (except fibre) increased or tended to increase with the CC diets, whereas gross milk composition was unaltered. Stearoyl-CoA desaturase-1 index for C18 (SCD18 ) was higher with CC-PMR than with SS-TMR, and milk n-6:n-3 FA ratio and apparent transfer of 18:2 n-6 to milk increased with CC diets. These results indicate that Opuntia stricta cladodes can be a valuable feed ingredient for improving the nutraceutical value of milk fat.