Rumen Morphometrics Research Articles

615 Rumen morphometrics of Nellore cattle submitted to either nutritional restriction or intake of concentrate feedstuffs prior to adaptation period

615 Rumen morphometrics of Nellore cattle submitted to either nutritional restriction or intake of concentrate feedstuffs prior to adaptation period

643 Effects of feeding functional oils or monensin on rumen morphometrics of Nellore cattle

643 Effects of feeding functional oils or monensin on rumen morphometrics of Nellore cattle

Effects of restricted vs. step up dietary adaptation for 6 or 9days on feedlot performance, feeding behaviour, ruminal and blood variables of Nellore cattle.

This study was designed to determine effects of quantitatively restricted intake of the final finishing diet as a means of dietary adaptation compared with diets increasing in concentrate (step up) over periods of 6 and 9 days on feedlot performance, carcass characteristics, feeding behaviour, blood gas profile and rumen morphometrics of Nellore cattle. One hundred twenty 22-month-old Nellore bulls (352±20kg) were randomly allocated in 24 pens and fed for 84 days. The experimental design was a completely randomized block with 2×2 factorial arrangement of treatments: adaptation using either step up protocol for 6 days or 9 days or restriction protocol for 6 days or 9 days, where the pen (five bullocks/pen; six pens/treatment) was considered the experimental unit. Cattle adapted by step up protocol had significantly greater average daily gain throughout the study when compared to those adapted by restriction protocol, regardless of adaptation length. During the adaptation period, a greater dry matter intake fluctuation was observed for animals maintained on restriction programme when compared to those adapted to the finishing diets using step up protocol. In addition, a protocol×length interaction for rumenitis scores was observed, where the level of injuries to the ruminal wall was significantly higher for the cattle adapted by restriction protocol for 9 days and lower for animals submitted for 9 days to the step up programme. Likewise, a protocol×length interaction for mitotic index was observed, in which cattle adapted by step up protocol for 9 days had lower numbers of cells in mitosis. Thus, the step up protocol led to better feedlot performance, and based on this fact, the length of 9days promoted better rumen epithelium adaptation of Nellore cattle to high-concentrate diets.

Relationships of feedlot performance, feeding behavior, rumen morphometrics, and carcass characteristics of Nellore cattle differing in phenotypic residual feed intake.

The objective of this study was to examine the relationship of DMI fluctuation, feedlot performance, feeding behavior, rumen morphometrics, and carcass characteristics in Nellore cattle classified by residual feed intake (RFI). One experiment was conducted in 2 consecutive years using individual pens (1.0 × 7.0 m) at the São Paulo State University feedlot, Dracena campus, Brazil. The experiment in year 1 started in June of 2012 with forty-eight 20-mo-old Nellore yearling bulls with an initial BW of 358.2 ± 19.4 kg. The experiment in year 2 started in January of 2013 with sixty 20-mo-old Nellore yearling bulls with an initial BW of 402.5 ± 33.0 kg. Experiments in years 1 and 2 lasted 94 and 84 d, respectively. All yearling bulls were categorized as high RFI (>0.5 SD above the mean, = 25), medium RFI (±0.5 SD from the mean, = 56), and low RFI (<0.5 SD below the mean, = 27). Visual appraisal to collect behavior data was made on d 40 (finishing period) of both years. Yearling bulls were harvested when average across treatment groups achieved a fat thickness of 4 mm at the 12th rib. Low-RFI yearling bulls had lower daily DMI, expressed either in kilograms ( < 0.01) or as percentage of BW ( < 0.01), and improved G:F ( < 0.01) when compared to high-RFI animals. No differences were observed ( > 0.10) for ADG, final BW, or HCW among RFI groups. Also, low-RFI yearling bulls had thinner final 12th rib ( < 0.01) and biceps femoris (P8) fat thickness ( < 0.01). Low-RFI yearling bulls were slower to consume ( = 0.03) and ruminate ( < 0.01) 1 kg of either DM or NDF. No significant ( > 0.10) RFI effect was observed for any ruminal morphometrics variables evaluated, with the exception of papillae area, in which low-RFI Nellore yearling bulls tended to have smaller ( = 0.07) papillae area than medium-RFI animals. In general, low-RFI Nellore yearling bulls consumed more particles larger than 19 and 8 mm and had a similar performance when compared to both medium- and high-RFI bulls; however, carcass fat composition was negatively impacted.

1660 Effects of conventional dietary adaptation over periods of 6, 9, 14, and 21 d on rumen morphometrics of Nellore cattle

1660 Effects of conventional dietary adaptation over periods of 6, 9, 14, and 21 d on rumen morphometrics of Nellore cattle

0251 Natural dry matter intake fluctuation impacts performance, feeding behavior and rumen morphometrics of feedlot cattle: 10 yr of data assessment

0251 Natural dry matter intake fluctuation impacts performance, feeding behavior and rumen morphometrics of feedlot cattle: 10 yr of data assessment

Efeito da casca de mandioca sobre a qualidade da carne e parâmetros ruminais de ovinos

This work evaluated different forms of processing of cassava peel for use in sheep feeding and its effects upon composition, meat quality, lipid profile and rumen morphometrics. A total of 20 weaned Santa Ines male sheeps, with initial weight 19.02±0.21 kg, were used. The fac-torial scheme utilized was a completely randomized design, with 4 treatments (A: supplement with dehydrated cassava peel ground, using a 12 mm sieve; B: supplement with dehydrated cassava peel ground using a 5 mm sieve; C: supplement with ensiled cassava peel; D: supplement with hydrolyzed cassava peel). Each animal was considered a replication, with 5 replications per treatment. The were reared in semiexten-sive system, on Brachiaria decumbens pasture. Treatments were supplied as supplement at proportion of 1.5 % of live weight (ratio roughage: concentrate of 62.5:37.5 %), amounts of food were adjusted, every week, according to the animals weight. The experiment lasted 84 days, including 14 days for adaptation to the diets. Animals were slaughtered at 30.72±1.46 kg final weight; after slaughter and cooling (24 hours at ±2 oC), samples of Longissimus lumborum muscle were collected to carry out the physicochemical analyses, and establish lipid profile. There were no significant differences for ashes, moisture and protein. The fed supplement with hydrolyzed cassava peel, presented higher values for ether extract. The fatty acid profile was not affected by processing type of cassava peels. The histological evaluation revealed alteration in the rumen epithelium and area of the omasal lamina, with higher values for coarsely ground cassava peel supplement. No influence of the supplements was found for physicochemical composition. The different supplements were not enough to alter the meat quality parameters, however, hydrolyzed cassava peel brought about increased accumulation of lipids in the muscle.

Rumen morphometrics and the effect of digesta pH and volume on volatile fatty acid absorption1

The effects of rumen digesta volume and pH on VFA absorption and its relation to rumen wall morphology were evaluated. Nine rumen cannulated cows formed 3 groups based on desired variation in rumen morphology: The High group was formed by Holsteins yielding 25.9 kg milk/d and fed on a high-grain total mixed ration (TMR); the Medium group by Holstein-Zebu crossbreds yielding 12.3 kg milk/d and fed on corn silage, tropical pasture, and a commercial concentrate; and the Dry group by nonlactating grazing Jerseys fed exclusively on tropical pasture. Within each group, a sequence of 3 ruminal conditions was induced on each cow in 3 × 3 Latin Squares, with 7-d periods: high digesta volume and high pH (HVHP), low volume and high pH (LVHP), and low volume and low pH (LVLP). Rumen mucosa was biopsied on the first day of Period 1. Ruminal morphometric variables evaluated were mitotic index, absorptive surface and papillae number per square centimeter of wall, area per papillae, papillae area as a percentage of absorptive surface, and epithelium, keratinized layer, and nonkeratinized layer thickness. There was marked variation in rumen morphology among the groups of cows. Grazing Jerseys had decreased rumen wall absorptive surface area and basal cells mitotic index, and increased thickness of the epithelium and of the keratin layer compared with cows receiving concentrates. Mean rumen pH throughout the 4 h sampling period was: 6.78 for HVHP, 7.08 for LVHP, and 5.90 for LVLP (P < 0.01). The capacity of the rumen wall to absorb VFA was estimated by the Valerate/CrEDTA technique. The fractional exponential decay rate for the ratio of valeric acid to Cr (k Val/Cr) was determined by rumen digesta sampling at 20-min intervals during 4 h, after the mixing of markers and the return of the evacuated ruminal content. The k Val/Cr values for treatments HVHP, LVHP, and LVLP were, respectively: 19.6, 23.9, and 35.0 %/h (SEM = 2.01; P = 0.21 for contrast HVHP vs. LVHP and P < 0.01 for contrast LVHP vs. LVLP). The k Val/Cr was faster under low pH, but decreasing digesta volume under high pH did not elicit such a response. The correlation between the absorptive surface area per square centimeter of rumen wall and the mean of the 3 k Val/Cr values of each cow was 0.90 (P < 0.01). Cows capable of maintaining a less-acidic rumen environment had greater inflow of water into the digestive cavity, had a more developed rumen mucosa, and were more efficient VFA absorbers.

BODY SIZE AND METABOLIC RATE

BODY SIZE AND METABOLIC RATE