Effect of undigested neutral detergent fiber content of alfalfa hay on lactating dairy cows: Feeding behavior, fiber digestibility, and lactation performance.

The objective of this study was to investigate the effects of 2 alfalfa hays differing in undigested neutral detergent fiber content and digestibility used as the main forage source in diets fed to high producing cows for Parmigiano-Reggiano cheese production. Diets were designed to have 2 different amounts of undigestible NDF [high (Hu) and low (Lu)], as determined by 240-h in vitro analysis (uNDF240). Alfalfa hay in vitro digestibility [% of amylase- and sodium sulfite-treated NDF with ash correction (aNDFom)] at 24 and 240 h was 40.2 and 31.2% and 53.6 and 45.7% for low- (LD) and high-digestibility (HD) hays, respectively. The 4 experimental diets (Hu-HD, Lu-HD, Hu-LD, and Lu-LD) contained 46.8, 36.8, 38.8, and 30.1% of alfalfa hay, respectively, 8.6% wheat straw, and 35.3% corn (50% flake and 50% meal; DM basis). Soy hulls and soybean meal were used to replace hay to balance protein and energy among diets. Eight multiparous Holstein cows (average milk production = 46.0 ± 5.2 kg/d, 101 ± 38 d in milk, and 662 ± 42 kg of average body weight) were assigned to a 4 × 4 Latin square design, with 2 wk of adaptation and a 1-wk collection period. Dry matter and water intake, rumination time, ruminal pH, and milk production and composition were measured. Diets and feces were analyzed for NDF on an organic matter basis (aNDFom), acid detergent fiber, acid detergent lignin, and uNDF240 to estimate total-tract fiber digestibility. Dry matter intake and rumination times were higher in HD diets compared with LD diets, regardless of forage amount. Rumination time was constant per unit of dry matter intake but differed when expressed as a function of uNDF240, aNDFom, or physically effective NDF intake. No differences were found among treatments on average ruminal pH, but the amount of time with pH <5.8 was lower in Hu-HD diets. Milk production and components were not different among diets. Total-tract aNDFom and potentially digestible neutral detergent fiber fraction digestibility was higher for the LD diets (88.3 versus 85.8% aNDFom in HD), for which lower feed intakes were also observed. The Hu-HD diet allowed greater dry matter intake, longer rumination time, and higher ruminal pH, suggesting that the limiting factor for dry matter intake is neutral detergent fiber digestibility and its relative rumen retention time.

Effect of age at slaughter on carcass traits and meat quality of Italian heavy pigs.

Barrows and gilts (n = 128) from four breed crosses were used to investigate the effect of age at slaughter on carcass traits, proteolytic enzyme activity, and meat and fat quality. Pigs were blocked by breed cross into four blocks, and within blocks, one pen (eight barrows and eight gilts) was assigned randomly to be slaughtered at either 8 or 10 mo of age. Pigs were fed a corn-barley-soybean meal finisher diet from 104 +/- 2.5 d of age (37.7 +/- 0.33 kg BW) to the appropriate slaughter age. Carcasses from older (10 mo) pigs had lower (P < 0.01) muscularity indexes and lean cut yields than those of younger (8 mo) pigs, but dressing percentage and longissimus muscle area increased (P < 0.01) with age. Older pigs produced a redder (P < 0.01) and darker (P < 0.05) semimembranosus, with lower (P < 0.01) ultimate pH and cathepsin B and B + L activities, as well as higher (P < 0.01) aminopeptidase hydrolyzing activity than younger pigs. Moreover, the longissimus muscle of pigs slaughtered at 10 mo of age had lower (P < 0.01) drip and cooking loss percentages than that from pigs slaughtered at 8 mo of age. Ham subcutaneous fat from 10-mo-old pigs had greater (P < 0.05) percentages of oleic acid and lower (P < 0.01) proportions of moisture, linoleic, and linolenic acids than subcutaneous fat from pigs slaughtered at 8 mo of age. Results from this study indicate that fresh hams from pigs slaughtered at 10 mo of age would be more suitable for the production of high-quality, Italian, dry-cured hams.

Lean colour of green and matured Parma hams: Comparative evaluation and technological relevance of sensory and objective data.

Research has been conducted on the relationship between sensory evaluation and objective measurement of pork colour. The study also investigated the relationship between the colour of fresh meat and the colour of matured hams. Sensory evaluation was carried out at 24 h post mortem on the freshly cut surfaces of green hams trimmed for Parma ham production. Objective measurements were performed at the same time on Semimembranosus and Biceps femoris muscles with a Minolta Chromameter Reflectance II CR200/08. Cold carcass weight, lean content, trimmed ham weight, 45 min and 24 h post mortem pH of Semimembranosus muscle were also recorded. The hams were processed according to Parma ham technology. Weight losses at standard processing times were collected. At the end of processing a sample of about one-third of the hams was evaluated for internal lean colour and lean firmness both by sensory panel and objective measurements. Proximate composition was also determined. The results showed highly significant relationships between colour sensory scores and the coordinates L (∗), b (∗) and hue of the C.I.E. L (∗)a (∗)b (∗) colour system. Among the other parameters measured on fresh meat only 24 h pH was related at a very significant level with sensory and objective colour values. Correlation coefficients were generally higher for Semimembranosus than Biceps femoris. Matured ham colour was linked with fresh meat sensory judgements, L (∗), hue and a (∗) values. The relationship, though, was not sufficiently strong for use in predicting the colour of matured hams from green ham characteristics. Processing appears to have a positive effect on the colour of pale meat. Weight losses were mainly linked with lean meat content; other quality attributes being less important. Lean firmness of matured hams was related to the colour and pH of the fresh meat.