Milk yield, intake, and blood traits of lactating cows fed grass silage conserved under different harvesting methods

Evaluation of alfalfa inter-seeding effect on bahiagrass baleage fermentation and lactating Holstein performance

Background

Previous research indicates that bahiagrass may be successfully conserved as baleage, but nutritive value is typically low for lactating dairy cows. The purpose of this study was to determine the effect of adding modest amounts of alfalfa forage (22%), achieved by inter-seeding alfalfa into an existing bahiagrass pasture, on baleage nutritive value and lactation performance of Holstein cows. Forage treatments employed were monoculture bahiagrass baleage (MBB; negative control), bahiagrass-alfalfa mixture baleage (BAB) and conventional corn silage (CCS; positive control). Thirty six mid lactation Holstein cows [34.8 ± 5.8 kg 3.5% fat-corrected milk and 112 ± 19 d in milk (DIM)] were stratified according to milk yield and DIM and assigned randomly to 1 of 3 forage treatments. Cows were trained to Calan feeding gates and were offered a common CCS-based TMR in a 10-d covariance period followed by a 42-d treatment feeding period.

Results

The BAB contained more protein and less NDF than MBB (12.6 vs 10.3% CP and 71.8 vs 76.6% NDF). Diet DMI was similar for MBB and BAB (19.5 vs 21.6 kg/hd/d), but cows consumed more of the CCS diet (25.5 kg/hd/d) than either baleage-based diet. Cows offered BAB tended to produce more milk than cows offered MBB based TMR (28.4 vs 26.1 kg/hd/d), but both baleage diets generated less milk than CCS-based diets (33.1 kg/hd/d). Milk composition was similar across diets except for milk protein concentrations which were higher for CCS than either MBB or BAB diets; however, milk urea nitrogen (MUN) was lowest for cows fed CCS diets. Cow BW gain was higher for BAB than MBB implying that a portion of the higher energy contributed by the alfalfa was being used to replenish weight on these mid lactation cows.

Conclusions

Data from this study indicate that alfalfa inter-seeded in bahiagrass sod that produces BAB with as little as 22% alfalfa may improve nutritive value compared to monoculture bahiagrass baleage and marginally improve lactation performance of Holstein cows. However, the CCS diet was vastly superior to either MBB or BAB-based diets for milk production.

Forage conservation efficiency and lactation response to bahiagrass conserved as barn-stored hay, outdoor-stored hay, or baleage

A study was conducted to determine the effect of conserving bahiagrass as outdoor-stored hay (OSH), barn-stored hay (BSH), or baleage (BAL) on storage losses and lactation performance by Holstein cows. For baleage production, bahiagrass forage was cut and allowed to dry for 20 h in windrows, baled (1.2 × 1.4 m), and individually wrapped with white stretch film. Forage cut on the same day was dried to hay stage, baled (1.2 × 1.6 m round bales), and stored either outdoors (OSH) or in an enclosed hay barn (BSH). Bales were core sampled and weighed at harvest and again following a 6-mo storage period. At the end of the storage period, 30 multiparous mid-lactation Holstein cows [39.2 ± 5.6 kg of 3.5% fat-corrected milk and 142 ± 27 d in milk (DIM)] were stratified according to milk yield and DIM and randomly assigned to 1 of the 3 forage conservation treatments. Cows were trained to Calan feeding gates and were offered a common partial mixed ration in a 10-d covariate period followed by a 42-d treatment feeding period. Forage dry matter losses were highest for OSH, but were similar between BSH and baleage. Conservation method had little effect on poststorage crude protein levels, but acid detergent fiber and neutral detergent fiber concentrations were higher in OSH than in either BSH or BAL, which resulted in a 12.8% depression in net energy for OSH compared with the other treatments. Dry matter intake (20.5 vs. 22.1 kg/d) and milk yield (28.2 vs. 30.2 kg/d) tended to be lower for OSH than for BSH. Lactation performance was similar between BSH and BAL: 29.6 versus 28.7 kg/d of fat-corrected milk, respectively. No differences in milk composition, feed efficiency, body weight, or body condition score change related to conservation system were observed. In this study, dry matter losses and lactation performance from bahiagrass conserved as baleage were similar to that of similar forage stored indoors as hay, whereas hay stored outside resulted in less satisfactory forage quality.

Aerobic stability of wheat and orchardgrass round-bale silages during winter

Using recently developed technology, balage is often stored in large (1.2 x 1.2 m) round bales that are wrapped in plastic film with an in-line wrapper. The aerobic stability of this fermented forage is important, particularly during winter months when it is fed to livestock or sold as a cash crop. Two types of forage, orchardgrass [Dactylis glomerata L.; 54.4% dry matter (DM)] and wheat (Triticum aestivum L.; 62.4% DM), were packaged in large round bales and wrapped with an in-line wrapper during May 2002. Twenty-one bales of each balage type were unwrapped and exposed to air on Dec. 10, 2002 for 0, 2, 4, 8, 16, 24, or 32 d (ambient temperature range = 0.6 to 19.4 degrees C) to evaluate aerobic stability. For both orchardgrass and wheat balage, final bale weight, concentration of DM, and pH were not affected by exposure time. Across both balage types, DM recoveries were > or = 97% for all bales, indicating that both balage types were very stable when exposed to air. For orchardgrass balage, exposure time had no effect on concentrations of NDF, ADF, hemicellulose, cellulose, or lignin, thereby indicating that little deterioration occurred. Similarly, no contrast relating any fiber component with exposure time was significant for wheat balage. Concentrations of crude protein (CP) were not affected by exposure time for wheat balage, but there was a tendency for exposed orchardgrass bales to have greater concentrations of CP than bales sampled on d 0. Exposure time had no effect on 48-h in situ digestibility of DM for wheat balage, but there was a tendency for a linear increase with exposure time for orchardgrass balage. However, the overall range (78.2 to 80.5%) over the 32-d exposure period was very narrow, and this response is probably of limited biological significance. Generally, concentrations of fermentation acids were low, primarily because of the high concentration of DM within these balages, and only minimal changes in these acids were observed over the exposure interval. These results suggest that the balage evaluated in this trial during winter conditions was very stable after exposure to air for up to 32 d. This should allow for considerable flexibility with respect to feeding, transport, and marketing of balage during winter months without significant aerobic deterioration.

Milk production and intake of lactating cows fed grass silage with protein and energy supplements

Primiparous (n = 8) and multiparous (n = 24) Holstein cows averaging 591 kg of BW (SE = 12) were allotted at 2 wk postpartum to eight blocks of 4 cows each on the basis of calving date and parity. Cows were fed timothy silage for ad libitum intake. The experiment was carried out between wk 4 and 15 of lactation. Cows within each block were assigned randomly to a concentrate containing soybean meal fed with corn, beet pulp, or a mixture of oats and barley (50: 50 on a DM basis) or fish meal fed with beet pulp. Concentrates were fed at about .8% of BW. The four treatments were designed to give similar CP and NEL intakes from the concentrate. Starch degradability and energy source (non-structural vs. structural carbohydrates) had no effect on total DMI of cows supplemented with soybean meal. Total DMI was similar for cows fed beet pulp with soybean meal or fish meal. Production of 4% FCM was on average 3.5 kg/d higher for cows fed beet pulp than starch. All cows gained BW. In low concentrate diets, beet pulp compared with starch improved N utilization of high moisture timothy silage by increasing production of 4% FCM without affecting total DMI; however, protein degradability does not seem to be important in low concentrate diets.

Fermentation and utilization of grass silage

The decision to utilize particular forages in support of dairy production should be based on a number of key factors, such as available land base, type of manure management, soil type and topography, climate, and availability of purchased forages and feeds. Because of the complexity and environmental concerns existing in the dairy industry today, decisions about forage and manure management should include whole farm analysis with the aid of computer software. The chemical composition and digestibility of grass are affected more by stage of maturity than by other management factors, such as species, DM, or type of harvest system. The decline in digestibility of nutrients in first growth forage is approximately .55 to .68%/d and is dependent on the method of estimation. The decline in digestible DMI in first growth is .3 to .5%/d. The use of silage additives has become an integral part of forage management, and improvements in DMI and milk production are documented. Particle size and type of harvest equipment significantly affect eating behavior and efficiency of milk production. Wilting of silage results in an increase in DMI and efficiency of microbial protein production.