The effects of the inclusion of either maize silage, fermented whole crop wheat or ure-treated whole crop wheat in a diet based on a high-quality grass silage on the performance of dairy cows

Sixteen multiparous Holstein/Friesian cows were used to examine the effect on food intake and milk production of replacing 40% of the dry matter (DM) of first cut perennial ryegrass silage (G) with either maize silage (M), fermented (F) or urea-treated (U) wheat whole crop silage. In addition to the forage mixtures, the animals received 5.25 kg DM d ^?1 of a standard concentrate and 1.75 kg DM d ^?1 of soya bean meal. The experiment consisted of four periods, each of 4 weeks duration, in a Latin square design. The grass silage used was of high quality with an estimated metabolizable energy (ME) content of 11.4 MJ kg ^?1 DM and in vitro digestibility of 748 g kg ^?1 DM. DM intake was significantly increased (s.e.d. = 0.364, P < 0.01) with the inclusion of M, F and U. The resulting total DM intakes were 17.6, 18.4, 19.2 and 20.1 kg d ^?1 for treatments G, M, F and U respectively. None of the animal production variables was significantly affected by the treatments. Milk yield was 27.4, 26.4, 27.1 and 26.9 kg d ^?1 for treatments G, M, F and U respectively. Milk fat content was 48.9, 46.9, 49.0 and 48.1 g kg ^?1, and milk protein content was 34.1, 33.6, 34.0 and 34.3 g kg ^?1 for treatments G, M, F and U respectively. The results show that partly (40%) replacing a high-quality grass silage with forage maize, fermented whole crop wheat or urea-treated whole crop wheat will increase DM intake in dairy cows but is not accompanied by an increase in animal performance and therefore will result in decreased efficiency of forage DM utilization.     

The use of n-alkanes to estimate herbage intake and diet composition by dairy cows offered a perennial ryegrass/white clover mixture

The n-alkane technique for estimating herbage intake and diet selection in dairy cows fed perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) herbages was evaluated. Pairs of animals were offered either 8, 10, 12 or 14 kg dry matter (DM) d^?1 of herbage alone or with 2 kg DM d^?1 of barley. Fresh herbage was cut daily from a perennial ryegrass/white clover sward and the appropriate amount was fed in four feeds during the day. Individual intakes and the white clover proportion of the diet were estimated during a 12-d period using the n-alkane technique. Animals were dosed twice daily with paper pellets containing dotriacontane (C₃₂-alkane). Faecal grab samples were collected after the morning and afternoon milking. Three least-squares optimization methods were compared in calculating the white clover proportion in the diet; then, total DM intake was calculated. The different least-squares optimization methods gave similar predictions of the white clover content of the forage consumed. No significant (P < 0.05) effects of sampling routine, concentrate (barley) fed or interactions between the two were detected with respect to the difference between calculated and actual intake, the difference as a proportion of the total intake and estimated white clover content of the diet. The difference between the calculated and actual intake ranged from 139 to 366 g DM d ^?1, which resulted in a proportional difference ranging from 0.004 to 0.02 depending on sampling routine. The actual white clover content of the herbage mixture fed was 0.42 ± 0.008, whereas the estimated white clover content ranged from 0.41 ± 0.006 to 0.43 ± 0.008. The results suggest that accurate herbage intake estimates can be achieved in dairy cows grazing perennial ryegrass/white clover swards if representative samples from herbage consumed can be collected.     

The effects of incorporating sugar beet pulp with forage maize at ensiling on silage fermentation and effluent output using drum silos

The effects of incorporating sugar beet pulp with forage maize at ensiling on silage fermentation, effluent output and pollution potential of the effluent was investigated using 200-litre drum silos. A forage maize crop (Zea mais) was harvested on four different dates, generating four different stages of maturity [dry-matter (DM) content 154–235 g kg⁻¹ DM], and molassed sugar beet pulp (MSBP) was added at five different rates (0, 2, 7, 13, 18 kg MSBP 100 kg⁻¹ fresh maize crop). A total of fourteen treatments (each replicated three times) were evaluated. The chemical analysis of the maize silages and the mixtures produced showed that MSBP addition increased DM, ash, neutral cellulase gaminase digestibility (NCGD) and metabolizable energy (ME) contents of the mixture significantly (P < 0·01) for all harvesting dates except for harvest date 1. Silage fermentation in terms of final pH was unaffected by MSBP addition, although lactic acid concentration of the effluent tended to increase with increased MSBP addition. When no MSBP was included, large volumes of effluent were produced, ranging from 200 g kg⁻¹ to 100 g kg⁻¹. MSBP addition significantly (P < 0·01) decreased effluent production except for the driest material. A curvilinear equation was fitted to predict effluent production from DM of the forage maize and pressure applied to the sample (adjusted r²=0·95). In addition, a curvilinear equation was fitted to predict the MSBP addition rate required to prevent effluent production (adjusted r²=0·65). For harvest dates 1, 2 and 3, the biological oxygen demand for 5 days (BOD₅) and the chemical oxygen demand (COD) concentration of the effluent were significantly increased (P < 0·05) with increased levels of MSBP addition. However, the pollution potential per kg of material ensiled was significantly reduced (P < 0·05) with increased MSBP addition, since less effluent was produced. The experiment indicates that ensiling low DM silages with appropriate levels of MSBP produces nutritionally valuable silages with reduced pollution potential.     

The effects of a foliar spray containing phosphorus and zinc on the development, composition and yield of forage maize

Forage maize grown in areas where spring temperatures are low and accumulated heat is limited will be restricted in terms of maturity and thus nutritional value. A stagnant growth phase is commonly caused by low temperatures between germination and the five-leaf stage, which could be caused by reduced mineral availability. The effects on maize plant development and harvest characteristics of supplying phosphorus and zinc to young plants in a foliar spray were investigated. Three different application dates, between the four-leaf and the seven-leaf stage, were compared. Applying the phosphorus and zinc foliar spray at the four-leaf stage resulted in a significant ( P  < 0·05) increase in starch content at harvest. Cob index [proportion of plant dry matter (DM) in the cob] was increased ( P  < 0·05) by applying the nutrient spray at the four-, five- and seven-leaf stages. However, there was no effect on DM yield, suggesting some alteration in partitioning within the plant.