254 Effects of Nutrition on Bull Fertility

The greatest effects of nutrition on bull fertility occur by providing a relatively high plane of nutrition during calfhood when the seminiferous epithelium of the testes is developing. A high plane of nutrition from 5 to 25 weeks of age results in greater circulating gonadotropin concentrations, greater testicular volume, and greater sperm production at maturity. At this age, diet can be manipulated by creep feeding bull calves with both protein and energy supplements which could accelerate puberty and increase sperm production. Increased rate of gain in bull calves post-weaning can accelerate puberty a few weeks, but excess post-weaning gain and fat buildup in the neck of the scrotum can have detrimental effects on fertility. Considerable emphasis has been placed on specific micronutrient (especially minerals) effects on peripubertal bull fertility. Trace mineral supplementation is believed to be critical for optimal fertility and both copper (Cu) and zinc (Zn) supplementation have influenced male fertility in other species. However, there are no guidelines for recommended levels of these minerals to ensure fertility. Providing organic or complexed compared to inorganic mineral to peripubertal bulls have increased liver concentrations of mineral and in some cases, have accelerated puberty, but enhanced fertility-associated measures have not been realized. Because both Cu and Zn are present in the ejaculate, mineral needs during the breeding season may differ from the off-season. During the breeding season, bulls can lose 10 to 20% of their weight and need to re-gain this weight before the next breeding season. Divergent planes of nutrition provided to mature bulls during the off-season revealed enhanced sperm energy and stress-fighting potential with decreasing plane of nutrition. Specific mineral supplementation during the off-season in mature bulls provides no beneficial effect on fertility-associated measures. In summary, significant effects of nutrition post-weaning on bull fertility-associated measures have not been realized.

Intake and digestibility in cattle grazing temperate grass associated with legume and/or energetic supplementation

The intercrop between grasses and legumes is an alternative to maintain and increase animal production. The study was conducted to evaluate the effect of grass-legume mixtures with or without supplementations on rumen fermentation, nutrient intake, and microbial protein synthesis. Six Holstein steers fitted with ruminal cannula were kept in a double 3 × 3 Latin square design. The treatments were: 1) oat, annual ryegrass, and supplement (GS), 2) oat, annual ryegrass, and vetch (GL), 3) oat, annual ryegrass, vetch, and supplement (GLS). Supplementation of ground maize was given daily at 11 h at 1% of body weight. Total digestible nutrient intake was higher in steers fed GS and GLS. Animals on GL ingested higher concentrations of nitrogen (N) compared to animals on GS and GLS diets. Ruminal pH and ammonia concentration were higher in GL. Grass-legume mixtures and supplements showed higher concentrations of sugar, α-amino acids, and peptides. The ruminal fermentative parameters, ruminal pH, ammonia, and sugars ranged cubically across the day. Microbial protein synthesis was similar amongst the treatments. Animals exclusively consuming temperate grass produce higher ruminal pH and ammonia concentrations. Therefore, using temperate legumes in pasture systems can be included in the cattle diet in lieu of utilizing energy supplements.

PSVIII-27 Interactions between the stage of maturity of Eragrostis tef hay and supplemental energy source on forage utilization in beef heifers

This study evaluated the interaction between the stage of maturity of Eragrostis tef (teff) grass and supplemental energy source on ruminal fermentation characteristics and nitrogen (N) utilization. Six ruminally-fistulated beef heifers were used in a 3 × 3 split-plot design (21 d periods). The whole plot factor was stage of maturity of teff hay [early- (EH) or late-heading (LH)], and the subplot factor was supplemental energy source [no supplement (CON), rolled corn grain or beet pulp pellet (BP)] fed at 0.5% of body weight. Feed intake was measured daily. Indwelling pH loggers were used to measure ruminal pH (d 14 to 21) and ruminal fluid was collected from d 19 to 21 to determine fermentation characteristics, as were feces and urine to measure N excretion. Data was analyzed using PROC MIXED in SAS. There was no stage of maturity × supplement interaction for all measurements (P ≥ 0.17). Although dry matter intake (DMI) tended to be greater (P = 0.07) for heifers fed EH than LH hay, it did not differ (P = 0.88) across supplements. Ruminal acetate concentration tended (P = 0.098) to be greater for EH than LH heifers, whereas butyrate, isobutyrate, and isovalerate concentrations were greater (P ≤ 0.045) for BPP than CON heifers. However, the duration and area pH < 6.2 and 5.8 did not differ (P > 0.12) across treatments. Except for microbial N flow, which was greater (P < 0.01) for EH than LH heifers, there was no stage of maturity or supplement effect (P ≥ 0.14) on measures of N utilization. In summary, feeding teff hay harvested at the EH than LH stage of maturity increased DMI and microbial N supply, whereas feeding corn and BP as energy supplements to beef heifers had no effect on ruminal pH.

201 Effects of feeding vitamin and mineral and (or) energy supplements to beef heifers during the first 83 days of gestation on progesterone concentrations, corpus luteum size, and fetal body measurements

Our objectives were to determine the effects of feeding vitamin and mineral (VTM) and (or) energy (NRG) supplements to beef heifers during the first 83 days of gestation on concentrations of progesterone (P4), corpus luteum (CL) size, and fetal body measurements. Crossbred beef heifers (n = 35; initial BW = 359.5 ± 7.1 kg) were blocked by weight and assigned to one of four treatments (n = 8 or 9/group) in a 2 × 2 factorial arrangement with main effects of vitamin and mineral (NoVTM or VTM) and energy (NoNRG or NRG) supplements. A basal total mixed ration was fed once daily with VTM and NRG top-dressed. The VTM treatment (113 g•heifer-1•d-1) was initiated 71 to 148 d before AI. At AI, heifers were bred to a single sire, and NRG was initiated with target gains of 0.28 kg/d for NoNRG and 0.79 kg/d for NRG. Serum was collected on d 14, 28, 42, 56, 70, and 83 after AI and analyzed for. Gravid reproductive tracts were collected by ovariohysterectomy on d 83 ± 0.27 of gestation, and fetuses were dissected. An NRG × day interaction (P = 0.006) was observed for P4, with concentrations similar on d 14 to 56, a tendency (P = 0.09) for divergence at d 70, and greater (P = 0.002) concentrations for NRG on d 83 compared with NoNRG heifers. Furthermore, NRG heifers had greater CL weights than NoNRG (P = 0.003). Fetuses from NRG dams had greater (P = 0.009) femur weights than fetuses from NoNRG. Fetal liver weight was greater (P = 0.05) from dams fed VTM than NoVTM. Overall, providing NRG supplements during early gestation resulted in heavier CLs, that produced more P4, and greater fetal femur growth, whereas providing VTM supplements enhanced fetal liver growth.

Influence of coniferous energy supplement on-breast productivity of cows

The article presents the results of the influence of coniferous-energy supplements on the qualitative and quantitative indicators of milk productivity. It was found out that the inclusion of 17 g / kg of dry matter of the ration in the diets of cows contributed to an increase in milk productivity and the biological value of milk.