Near-infrared spectroscopy for rapid evaluation of winter cereals and Italian ryegrass forage mixtures.

Near-infrared (NIR) spectroscopy was employed to determine the differences between forage mixtures of winter cereals and Italian ryegrass and to evaluate fermentation characteristics of mixed silages. Forages were harvested on five phases (Cuts 1-5), with 1 week interval (n = 100). The yield of the last harvest (Cut 5) was ensiled and analyzed on four different days (D0, D7, D14, and D90) (n = 80). Principal component analysis based on the NIR data revealed differences according to the days of harvest, differences between winter cereals and Italian ryegrass forages, and differences in the fermentation stages of silages. The partial least square regression models for crude protein (CP), crude fiber (CF), and ash gave excellent determination coefficient in cross-validation (R2 CV > 0.9), while models for ether extract (EE) and total sugar content were weaker (R2 CV = 0.87 and 0.74, respectively). The values of root mean square error of cross-validation were 0.59, 0.76, 0.22, 0.31, and 2.36 %DM, for CP, CF, EE, ash, and total sugar, respectively. NIR proved to be an efficient tool in evaluating type and growth differences of the winter cereals and Italian ryegrass forage mixtures and the quality changes that occur during ensiling.

Evaluation of physical structure value in spring-harvested grass/clover silage and hay fed to heifers.

The physical structure value of conserved grass/clover forages of spring harvest was evaluated by assessing effects of harvest time, conservation method, iNDF/NDF ratio and NDF intake (NDFI) per kg BW on chewing activity and fecal particle size in dairy heifers. A mixed sward consisting of ryegrass (Lolium perenne), red clover (Trifolium pratense) and white clover (Trifolium repens) was harvested in 2009 on May 9 (early) and 25 (late), and both cuts were conserved as silage and hay. The early silage, early hay, late silage and late hay contained dry matter (DM) of 454, 842, 250 and 828 g/kg, and NDF of 315, 436, 414 and 503 g/kg DM, respectively. Forages were fed as sole feed to four Jersey heifers of 435±30 kg BW in a 4×4 Latin square experiment. Feeding level was 90% of individual ad libitum intake, divided equally across two daily meals offered at 0800 and 1530 h. Chewing activity was estimated from recorded jaw movements (JM) oscillations continuously logged for 96 h and summarized per 24 h as mean effective rumination time and eating time. Eating behavior was further observed during four 20-min test meals. Weight proportion of large feces particles (>1.0 mm) and geometric mean fecal particle size (GPS) were calculated. Potentially indigestible NDF (iNDF) was estimated by incubation for 288 h in situ. The daily DM intake (DMI) decreased with progressing maturity at harvest (P<0.001) while daily NDFI was unaffected by harvest time (P>0.05). Earlier harvest led to less rumination per kg NDFI (P<0.01), similar eating time per kg NDFI (P>0.05) and similar proportion of large particles (P>0.01) compared with later harvest. Rumination time per kg NDFI decreased with higher NDFI per kg BW (P<0.001) and with lower iNDF/NDF ratio (P<0.01). Content and potential digestibility of NDF was greater in hay than in silage from the same harvest probably due to field loss and therefore confounded effects of conservation method. This study of high digestibility grass/clover silage and hay showed that NDF content and NDFI per kg BW affect fecal particle size and rumination time per kg NDF, and suggests implementation of NDFI per kg BW in systems evaluating physical structure in diets.

Use of F57 bags by the semi-automatic in vitro technique of gas production / Uso de sacos F57 pela técnica in vitro semi-automática de produção de gases

Os cadinhos filtrantes (porosidade 1) originalmente usados na técnica in vitro semi-automática de produção de gases estabelecida no Laboratório de Produção de Gases da Escola de Veterinária da UFMG podem ocasionar interferências nos estudos de quantificação da degradação de alimentos, principalmente os ricos em amido, devido à obstrução dos poros da placa filtrante pelo material residual após fermentação. Este estudo objetivou avaliar a substituição dos cadinhos filtrantes por sacos F57 (Ankom(r)) visando a realização de experimentos in vitro para descrição da cinética de fermentação e degradação ruminal. Esta substituição causou a redução do peso/volume da amostra incubada e desta forma, interferiu na relação pressão (P) / volume (V) e consequentemente inviabilizou a utilização de equação previamente estabelecida por Mauricio et al. (2003). Desta forma, objetivou-se neste estudo estabelecer equação para estimar o volume de gases produzidos a partir de dados de P e V obtidos pela fermentação de sorgo forrageiro, incluindo partes da planta e planta inteira, incubados em sacos F57 (Ankom(r)). Foram quantificados 474 dados simultâneos de pressão e volume os quais variaram de 0 a 4.670 psi e os de volume entre 0 e 38mL. A equação relacionando P e V obtida foi: V (mL) = 0.747 (s.e. 0.0733) + 7.23 P (s.e. 0.1165) + 0.101 P2 (s.e. 0.0372), (R2 = 0.99). O desenvolvimento desta equação viabilizou a utilização dos sacos F57 (Ankom(r)) pela na técnica in vitro semi-automática de produção de gases e, portanto permitindo a quantificação dos resíduos da fermentação favorecendo a acurácia dos resultados...

Intake, digestibility, nitrogen efficiency, and animal performance of growing and finishing beef cattle fed warm-season legume (Stylosanthes capitata plus Stylosanthes macrocephala) silage replacing corn silage.

It was hypothesized that Stylosanthes cv. Campo Grande (ES) silage could be used as the single source of dietary forage for beef cattle and that performance on ES would be similar to corn silage (CS) at a 50:50 forage:concentrate. The objectives of this study were to evaluate intake, total and partial digestibility of nutrients, ruminal pH, ruminal ammonia, and productive performance in growing beef cattle fed diets with varying proportions of ES silage replacing CS. Treatments consisted of diets with ratios of 0:100, 25:75, 50:50, 75:25, and 100:0% ES:CS. Two experiments were conducted simultaneously. In the first experiment, 10 crossbred Holstein-Zebu bulls with an average initial weight of 272 ± 86 kg were used. The bulls were rumen and abomasums fistulated. An experimental design of two 5 × 5 Latin squares (Exp. 1) was used. The second experiment used 40 Nellore bulls with an average BW of 386 ± 30 kg in a completely randomized design (Exp. 2). Results showed a linear increase in CP intake (P < 0.05) in response to increased dietary ES. An increase in the proportion of ES in the diet had a negative linear effect on TDN. Apparent ruminal digestibility of CP increased linearly, and apparent intestinal digestibility of nonfibrous carbohydrates increased with the addition of ES to the diet (P < 0.05). Intestinal digestibility of DM exhibited a quadratic response (P < 0.05). Nitrogen balance, excretion of urinary urea, and plasma urea nitrogen did not respond to the inclusion of ES in the diet (P > 0.05). There was also no effect (P > 0.05) of ES inclusion on animal performance. Ruminal pH was not affected by an increased proportion of ES in the diet (P > 0.05), but ruminal pH was affected (P < 0.05) by the time of collection, for which a cubic model fit the data. There was an interaction (P < 0.05) between treatment and collection time for ruminal ammonia nitrogen concentration. It can be concluded that ES silage can be used as a source of roughage in the diet of beef cattle during the growing and finishing phases at a proportion of 50% of DM in the total diet. Therefore, ES silage is a promising alternative dietary ingredient and the use of this alternative source of silage will depend on availability and economic factors.