The assessment of the level of nutrition of dairy cattle in relation to their milk pruduction was carried out under operating conditions. The focus was on the quality of the roughage feed, the feeding technique, the contents of the diet and the supply of nutrients. On the basis of operating and economic indicators, the milk production costs as well as an overall evaluation summing the individual observed periods have been calculated. The results of the observation of the level of nutrition over a three-year period indicate that the feed rations are prepared according to the optimal standards. In the observed periods, first quality* corn silage and first or second quality** corn silage was always used. The average efficiency of a cow reached 7 000 kg of milk per year. The average cost of one litre of thus produced milk was 9,30 CZK in an average day, and the average sum of money needed came in at 138,37 CZK.

Doctor of Philosophy / Department of Animal Sciences and Industry / Barry Bradford / High levels of milk production has been and will continue to be a priority for the global dairy industry. Non-steroidal antiinflammatory drugs administered to dairy cattle following calving can be an effective way of programming higher milk production for the entirety of lactation. When dairy cattle on a commercial dairy received either sodium salicylate or meloxicam following calving, they responded with increased whole-lactation milk production, which was driven by higher daily milk yields following the seventh week of lactation. When dairy cattle at a research dairy received sodium salicylate following calving, they did not show the same increase in milk production but feed intake, feeding behavior, and blood parameters were altered for an extended period of time. The response to treatment was largely dependent on the parity of the animal. In an effort to determine whether re-programming of the rumen environment could explain these findings, sodium salicylate was administered to batch cultures of rumen fluid, and as a result, fermentation was inhibited. When substrate was fermented in rumen fluid from heifers who had been dosed with sodium salicylate, fermentation was inhibited for an extended period of time following sodium salicylate administration. Beyond the use of compounds such as these, other factors can program lactation for higher milk production, including the gender of the calf. Analysis of lactation records from the US has indicated that cows produce more milk following the birth of a heifer calf compared to a bull. With further research, findings such as these can provide farmers with more tools for improving productivity and lead to the sustainability of the dairy industry as a whole.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Genetic selection for high milk production, type and appearance for the last 50 years has suppressed secondary traits such as reproductive performance, productive life, health and survivability in the pure milk breeds. The economic importance of these secondary traits in dairy production systems is the basis for the interest seen in crossbreeding. The problem of growth rate of heifers, cow fertility, reduced disease resistance and small body frame for beef production in Jerseys can be improved by crossing Jerseys with dual purpose breeds, such as Fleckviehs which possess a more beef potential. Against this background, this study aimed at comparing the production and reproduction of Jersey and Fleckvieh × Jersey cows in a pasture-based system. Milk recording was done according to standard milk recording procedures. Milk production (milk, fat, and protein yield) was adjusted to 305 days of lactation and corrected for age at calving. Effects of breed, parity, month and year were estimated for milk, fat and protein yield as well as fat and protein percentage using general linear models procedure. The fixed effects identified as having significant effects on milk, fat and protein yield were breed, parity and year. F×J cows produced significantly more milk than J cows (6141 ± 102 vs. 5398 ± 95 kg milk). Protein and fat yield were significantly higher in F×J (201 ± 3 and 272 ± 4 kg, respectively) than in J cows (194 ± 2 and 246 ± 3 kg, respectively). There percentages of fat and protein differed slightly between the two breeds with the Jersey recording slightly higher percentages (4.61 ± 0.04 and 3.62 ± 0.03 %, respectively) compared to the F×J cows’ percentages, which were, respectively, 4.47 ± 0.04 and 3.51 ± 0.03 %. It was concluded that F×J crossbred cows were more productive than purebred J cows probably owing to heterotic effects. Heifers were inseminated at 13 months of age and cows 40 days post-calving. Using insemination records and pregnancy check results, fertility traits were analyzed and compared between the two breeds, using analysis of variance for continuous records. Conception age was the same for both breeds resulting in a similar age at first calving. For cows, the interval from calving to first insemination was significantly shorter (P <0.001) in crossbred cows being 76.7 ± 2.2 days compared to 82.4 ± 2.5 days for purebreds. A larger proportion (P < 0.001) of 0.70 for crossbred cows was inseminated within 80 days after calving compared to 0.54 for J cows. Although the absolute number of days between calving and conception (DO) was lower for F×J cows in comparison to J cows (104.8 ± 6.8 vs. 114.8 ± 8.1days, respectively), the difference was not significant. However, the proportion of F×J cows confirmed pregnant by 100 days in milk was 0.79, which was higher (P < 0.001) than the 0.66 for J cows. Results indicate the potential of improving reproductive performance of J cows through crossing with dual-purpose breeds. The beef production of purebred J and Fleckvieh x Jersey (F×J) bull calves was compared, where bull calves were reared similarly for veal, i.e. carcass weight not exceeding 100 kg, or as steers for beef to 21 months of age. In both the veal and steer production systems, the mean birth weight were higher (P < 0.001) for crossbred in comparison to J calves and steers (33.5 ± 1.2 kg vs. 27.9 ± 1.2 kg for veal) and (33.4 ± 0.9 kg vs. 26.9 ± 0.9 kg for steers) respectively. The live weight at 6 months of age was 163.5 ± 3.9 kg for J bull calves, which was lower (P < 0.001) than that for F×J bull calves (180.6 ± 4.0 kg). The F×J bull calves had a significantly higher average daily gain (ADG) of 0.82 ± 0.02 kg/day compared to 0.73 ± 0.02 kg/day for J bulls. Marketing age differed (P < 0.001) in the veal production system with F×J and J bull calves marketed at 7.1 ± 0.1 and 6.3 ± 0.1 months, respectively. End live weight at 21 months of age was significantly higher (P < 0.001) in F×J bulls (441.4 ± 14.9 kg) than the 322.6 ± 13.4 kg in J bulls; while ADG differed (P < 0.001) between the two breeds being 0.64 ± 0.02 and 0.46 ± 0.0 kg/day in F×J and J bull calves, respectively. Crossbred steers had a significantly higher carcass of 206.5 ± 8.9 kg compared to 157.9 ± 8.6 kg for J steers. Results indicate the potential of improving beef production characteristics of the J cattle through crossbreeding. / AFRIKAANSE OPSOMMING: Genetiese seleksie vir hoë melkproduksie, tipe en voorkoms die afgelope 50 jaar het sekondêre eienskappe soos reproduksie, produktiewe lewe, gesondheid en oorlewing onderdruk in die suiwer melk rasse. Die ekonomiese belangrikheid van hierdie sekondêre eienskappe in melkproduksie stelsels is die basis vir kruisteling. Probleme soos groei tempo van verse, koei vrugbaarheid, verlaagde weerstandbiedenheid teen siektes en klein liggaam raam vir vleisproduksie in Jerseys kan verbeter word deur die kruising van Jerseys met ' n dubbele doel rasse, soos Fleckviehs wat beskik oor beter vleis potensiaal. Teen hierdie agtergrond, is hierdie studie daarop gemik om produksie en reproduksie van Jersey en Fleckvieh x Jersey koeie in 'n weiveld - gebaseerde stelsel te vergelyk. Melk opname is gedoen volgens standaard melkaantekening prosedures. Melkproduksie (melk-, veten proteïen opbrengs) was aangepas vir 305 dae van laktasie en gekorrigeer vir kalf ouderdom. ‘n Algemene lineêre model was gebruik om die effekte van ras, pariteit , maand en jaar op melk-, vet- en proteïen opbrengs sowel as vet- en proteïen persentasie te bepaal. Die vaste effekte geïdentifiseer met 'n beduidende effek op melk-, vet- en proteïen opbrengs was ras, pariteit en jaar. F × J koeie het aansienlik meer melk as J koeie (6141 ± 102 teen 5398 ± 95 kg melk) produseer . Vet opbrengs was aansienlik hoër in F × J koeie as in J koeie (272 ± 4 246 teen ± 3 kg vet). Proteïen opbrengs was ook aansienlik hoër in F × J koeie as J koeie (201 ± 3 vs 194 ± 2 kg proteïen). Vet en proteïen persentasies het geneig om effens te verskil met 'n klein effek (4.61 ± 0.04 % vet en 3.62 ± 0.03 % proteïen) vir J koeie en (4.47 ± 0.04 % vet en 3.51 ± 0.03 % proteïen) vir F × J koeie. Daar is tot die gevolgtrekking gekom dat F × J gekruisde koeie kan meer produktief wees as suiwer J koeie weens heterotiese effekte. Verse kunsmatig geïnsemineer was op 13 maande ouderdom en koeie 40 dae na- kalwing aangehou was. Met behulp van bevrugting en swangerskap rekords, is vrugbaarheid eienskappe ontleed en vergelyk tussen die twee rasse, met behulp van ontleding van variansie vir deurlopende rekords. Ouderdom van bevrugting was dieselfde vir beide rasse wat in 'n soortgelyke ouderdomsgroep was by eerste kalwing. Vir koeie was die interval van kalf tot eerste inseminasie aansienlik korter (P < 0.001) vir kruisgeteelde koeie wat 76.7 ± 2.2 dae in vergelyking met 82.4 ± 2.5 dae suiwerrasse is. ‘n Groter proporsie ( P < 0.001) van 0.70 vir gekruisteelde koeie is binne 80 dae na kalwing geïnsemineer in vergelyking met 0.54 vir J koeie. Alhoewel die absolute aantal dae tussen kalwing en opvatting (DO) laer was vir F × J koeie in vergelyking met J koeie (104.8 ± 6.8 teen 114.8 ± 8.1dae, onderskeidelik), is die verskil nie betekenisvol nie. Maar die verhouding van F × J koeie wat swanger bevestig is met 100 dae in melk was 0.79, wat hoër was (P < 0.001) is as die 0.66 vir J koeie. Resultate dui daarop dat daar potensiaal is reproduktiewe prestasie te verbeter van J koeie deur kruisteling met 'n dubbel- doel rasse. Die vleisproduksie van suiwer J en Fleckvieh x Jersey (F × J) bulkalwers vergelyk. Die bul kalwers is soortgelyk grootgemaak vir kalfsvleis, d.w.s karkas gewig mag nie 100 kg oorskry as bulkalwers nie, en as osse vir vleis tot 21 maande oud. In die kalwers- en os produksie stelsels, was die gemiddelde geboorte gewig hoër (P < 0.001) vir die kruise in vergelyking met J kalwers en osse (33.5 ± 1.2 kg teen 27.9 ± 1.2 kg vir kalwers) en (33.4 ± 0.9 kg vs . 26.9 ± 0.9 kg vir osse) onderskeidelik . Die lewendige gewig op 6 maande ouderdom was 163.5 ± 3.9 kg vir J bulkalwers en was hoër (P < 0.001) vir F × J bulkalwers 180.6 ± 4.0 kg. Die F × J bul kalwers het 'n aansienlik ‘n hoër gemiddelde daaglikse toename (GDT) van 0.82 ± 0.02 kg/dag in vergelyking met 0.73 ± 0.02 kg/dag vir J bulle. Bemarkingsouderdom verskil (P < 0.001) in die kalf produksie stelsel met F × J en J bulkalwers bemark op 7.1 ± 0.1 en 6.3 ± 0.1 maande , onderskeidelik. Finale lewendige gewig van 21 maande oud was aansienlik hoër 441.4 ± 14.9 kg in F × J bulle as 322.6 ± 13.4 kg in J bulle , terwyl GDT hoër was (P < 0.001), met 0.64 ± 0.02 kg/dag en 0.46 ± 0.0 kg/dag in F × J en J bulkalwers, onderskeidelik. Gekruisde osse het 'n aansienlik hoër karkasgewig 206.5 ± 8.9 kg in vergelyking met 157.9 ± 8.6 kg van J osse. Resultate dui daarop dat daar potensiaal is om die beesvleis produksie-eienskappe van die J beeste te verbeter d.m.v. kruisteling.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Little research has been done on natural feed additives which enhance milk production in dairy animals. Fenugreek (Trigonella foenumgraecum) is a member of the legume family and is found in India, Middle East, North Africa and South Europe. Fenugreek is used as an herb in traditional medicine to promote lactation in lactating women. It also influences the lactation performance in ruminants such as dairy cows, water buffaloes and dairy goats. Diocin is a natural saponin found in Fenugreek and has structural similarity to oestrogen, which leads to an increased release of growth hormone (GH) and ultimately milk production. Three different trials were carried out to investigate Fenugreek’s effects. Each trial consisted of three treatment groups where dairy goats were randomly assigned. Nutrifen®, NutrifenPlus® and a control treatment served as the three treatments used in this study. Forty-eight goats per treatment group were used in the first trial where the main objective was to evaluate Fenugreek’s effect on milk production and milk composition. The second trial consisted of eight goats per treatment group, where Fenugreek’s effect on the in vivo and in vitro digestibility of the feed served as the main objective of this study. In the final part of the study, growth hormone found in plasma was subsequently investigated using the same goats from trial two. Fenugreek’s effect on elevating GH levels was the objective from the third part of the study. The first trial showed promising results in terms of an increase in milk production (P = 0.01) from dairy goats using the Nutrifen® treatment and an increase in milk lactose (P = 0.03) using the NutrifenPlus® treatment. Blood cholesterol and cholesterol content found in the milk did not differ between treatments used. Apparent digestibility of the total digestible nutrients (TDN) from the feed did not increase and did not differ between treatments and therefore concluded that the dairy goats digested the different treatments with similar efficiency regardless of the additive added to the feed. Growth hormone levels found in plasma also did not differ between treatments used in the third part of the study. Variation was found in GH plasma levels and this was expected as GH levels are known to have variation within ruminants. It appears that Fenugreek used as a natural feed additive can increase the milk yield from dairy goats, which would be beneficial to the commercial dairy goat farmer. However, the process on how Fenugreek exerts its effect on milk production still remains unclear. / AFRIKAANSE OPSOMMING: Tot datum is min navorsing gepubliseer wat die invloed van natuurlike voer bymiddels op melkproduksie aanspreek. Fenugreek (Trigonella foenumgraecum) is ‘n peulgewas en kom voor in Indië, die Midde Ooste, Noord Afrika en Suid Europa. Fenugreek word in tradisionele medisyne gebruik om sodoende melkproduksie in lakterende vroue te verhoog. Dit verhoog ook melkprodukise in melkkoeie, waterbuffels en melkbokke. Diocin is ‘n natuurlike saponien, met sterk oestrogeniese strukturele ooreenkomste, wat in Fenugreek voorkom. Diocin lei tot die verhoogde afskeiding van groeihormoon (GH) en uiteindelik ‘n toename in melkproduksie. Drie proewe is uitgevoer ten einde die effek van Fenugreek te ondersoek. Elke proef het bestaan uit drie behandelingsgroepe en melkbokke is ewekansig aan die groepe toegedeel. Nutrifen®, NutrifenPlus® en ‘n kontrole sonder enige additief is gebruik as behandelings. Agt-en-veertig bokke is per behandeling gebruik in die eerste proef. Die doel van hierdie proef was om die invloed van Fenugreek op melkproduksie en melksamestelling te bepaal. Die tweede proef het agt bokke per behandelingsgroep gehad en het ten doel gehad om te bepaal wat die invloed van Fenugreek op die in vitro en in vivo verteerbaarheid van die voere was. In die derde proef is dieselfde bokke as die in proef twee gebruik en hier is groeihormoon vlakke in sirkulerende bloedplasma gemeet om die invloed van Fenugreek op hierdie parameter te bepaal. Resultate van die eerste proef het getoon dat melkproduksie van bokke wat Nutrifen® ontvang het betekenisvol verhoog het (P = 0.01) terwyl NutrifenPlus® gelei het tot ‘n verhoging (P = 0.03) in melk laktose vlakke. Bloed cholesterol en melk cholesterol vlakke was onveranderd. Skynbare verteerbaarheid van die totale verteerbare voedingstowwe (TVV) van die voer het nie verander (P = 0.34) met die insluiting van Fenugreek nie. Plasma groeihormoonvlakke was nie betekenisvol verskillend (P > 0.05) tussen behandelingsgroepe nie en die gebrek aan verskille kan waarskynlik toegeskryf word aan die variasie wat binne behandelings groepe opgemerk is vir hierdie parameter. Sodanige variasie in plasma groeihormoon word as algemeen beskou in herkouers. Gevolglik kan aanvaar word dat die natuurlike voerbymiddel, Fenugreek, gebruik kan word om melkproduksie in lakterende melkbokke te verhoog. Hierdie praktyk behoort voordele in te hou vir die kommersiële melkprodusent. Die proses waardeur hierdie verhoging plaasvind is egter steeds nie duidelik nie.

Effects of a short 40-d dry period with only a close-up diet (SHORT) and a conventional 60-d dry period with a 39-d far-off and a 21-d close-up diet (CONV) on milk production, feed intake, blood and rumen parameters, liver gene expression and rumen microbiota profile were compared in 11 second-parity and 15 third and later parity cows. Milk production was recorded daily during the first 16 wks of lactation. Differential liver gene expression was assessed by affymetrix microarray analysis and DNA extracted from rumen samples was subjected to Illumina sequencing for exploring the microbiome profile. The SHORT treatment reduced milk yield and DMI after calving in third and later parity cows, but not in second-parity cows when compared to the CONV treatment. Cows on the SHORT treatment had higher concentrations of NEFA in blood plasma and tended to have higher liver TAG immediately after calving. These effects tended to be greater in third- and later parity cows compared to second-parity cows. Expression patterns of genes involved in β-oxidation at the first week of lactation compared to those at three weeks before calving showed lower hepatic β-oxidation capacity in cows on the SHORT treatment compared to those on the CONV treatment. During this period, the expression of DGAT, a key gene in the triglyceride synthesis, increased in SHORT-treatment cows while it remained unchanged in CONV-treatment cows. The expression patterns of genes involved in gluconeogenesis showed a higher capacity at first week after calving in cows on the SHORT compared to those on the CONV treatment. Our study also showed that the SHORT treatment increased the relative abundance of Firmicutes and reduced the relative abundance of Bacteroidetes compared to the CONV treatment and reduced the shifting of rumen microbiota from before to after calving. Results also demonstrated that the rumen microbiota was more stable in the SHORT treatment during the transition period. Based on these results, a 40-d dry period management with only a close-up diet might be beneficial for second parity cows. However, this treatment may be detrimental for older cows as excessive energy intake and fat deposition during the dry period in these animals result in lower milk production and higher mobilization of NEFA and accumulation of fat in the liver. / February 2016

Master of Science / Department of Clinical Sciences / Daniel U. Thomson / Bovine respiratory disease (BRDC) is a multifaceted disease that causes considerable economic loss in both the beef and dairy industry. However, because there may be lingering effects of BRDC in the dairy industry, the full economic costs of the disease may not be realized. These lingering effects may include an increased departure from the herd, decreased milk production, and decreased reproductive performance. All of these outcomes are affected by multiple variables, but proper statistical modeling can control for many of the different influences. Few studies have attempted to look at the long term effects of calfhood BRDC but consistent associations have not been identified. The objective of this observational, retrospective study was to determine the association between calfhood BRDC prior to 120 d of age and departure from the herd, milk production, and reproductive performance. The association between the occurrence of BRDC with departure from the herd prior to first calving depended on the birth year, but for 5 of the 6 years, animals that contracted BRDC were 1.62 to 4.98 times more likely to leave the herd than animals that did not contract BRDC. In addition, animals that contracted BRDC were also 1.28 times more likely to leave the herd between first and second calving than animals that did not contract BRDC. Furthermore, the age at BRDC occurrence was associated with departure from the herd. Animals that contracted BRDC pre-weaning were 2.62 times more likely to leave the herd prior to first calving than animals that contracted BRDC post-weaning. However, age of BRDC occurrence was not significantly associated with departure from the herd between first and second calving. The occurrence of BRDC during the first 120 d of life was associated with a 233 kg decrease in lactation-one production, but was not significantly associated with production in subsequent lactations. Finally, calfhood BRDC was not significantly associated with a decreased reproductive performance measured by calving interval. In conclusion, calfhood BRDC negatively impacts productivity both prior to and after first calving.

Doctor of Philosophy / Department of Animal Sciences and Industry / Barry Bradford / High levels of milk production has been and will continue to be a priority for the global dairy industry. Non-steroidal antiinflammatory drugs administered to dairy cattle following calving can be an effective way of programming higher milk production for the entirety of lactation. When dairy cattle on a commercial dairy received either sodium salicylate or meloxicam following calving, they responded with increased whole-lactation milk production, which was driven by higher daily milk yields following the seventh week of lactation. When dairy cattle at a research dairy received sodium salicylate following calving, they did not show the same increase in milk production but feed intake, feeding behavior, and blood parameters were altered for an extended period of time. The response to treatment was largely dependent on the parity of the animal. In an effort to determine whether re-programming of the rumen environment could explain these findings, sodium salicylate was administered to batch cultures of rumen fluid, and as a result, fermentation was inhibited. When substrate was fermented in rumen fluid from heifers who had been dosed with sodium salicylate, fermentation was inhibited for an extended period of time following sodium salicylate administration. Beyond the use of compounds such as these, other factors can program lactation for higher milk production, including the gender of the calf. Analysis of lactation records from the US has indicated that cows produce more milk following the birth of a heifer calf compared to a bull. With further research, findings such as these can provide farmers with more tools for improving productivity and lead to the sustainability of the dairy industry as a whole.

O objetivo foi avaliar o efeito de teores de proteína bruta (PB) (14,5 vs 16%) e da fonte nitrogenada na dieta de vacas leiteiras em lactação sobre o consumo e digestibilidade da matéria seca (MS) e nutrientes, fermentação ruminal, produção e composição do leite e balanço de energia, utilizando cana-de-açúcar como volumoso. Foram utilizadas 12 vacas Holandesas com média de 235 dias em lactação, agrupadas em três quadrados latinos 4x4 contemporâneos, com período experimental de 21 dias, sendo 14 para adaptação às dietas e os 7 últimos para coletas. As vacas foram alimentadas &quot;ad libitum\' com rações isoenergéticas, com duas fontes nitrogenadas principais (farelo de soja e uréia) e dois teores de PB (14,5 e 16,0 %) na dieta: A) 16% PB e farelo de soja (FS) como fonte nitrogenada, com 65% de PDR; B) 14,5% PB e uréia (U) como fonte nitrogenada, com 70% de PDR; C) 16% PB U e 70% de PDR; D) 14,5% PB FS e 65% de PDR na MS. As amostras de leite para análise da composição foram coletadas do 14º ao 17º dia de cada período. As amostras de líquido ruminal foram coletadas com a utilização de sonda esofágica, três horas após a alimentação matinal. A digestibilidade foi determinada por meio de indicador interno FDAi. Não houve efeito das dietas sobre o consumo de MS (Kg/dia), de energia líquida de lactação (Mcal/dia), coeficiente de digestibilidade em porcentagem e consumo em porcentagem do peso vivo. Houve interação entre fonte nitrogenada e teor de PB da dieta sobre o pH e relação acetato propionato. Houve tendência (P=0,052) da fonte nitrogenada para PB (kg/dia), na qual as dietas com farelo de soja apresentaram maior valor, quando comparada as dietas com ureia. A gordura do leite foi maior (4,06%) nas dietas com fonte nitrogenada ureia , em relação a fonte nitrogenada FS com (3,5%). / The objective was to evaluate the effect of crude protein (CP) (14.5 vs. 16%) of the nitrogen source in the diet of lactating dairy cows on intake and digestibility of dry matter (DM) and nutrients, rumen fermentation, production and milk composition, energy balance, using sugar cane as forrage. We used 12 Holstein cows averaging 235 days in milk, grouped in three 4x4 contemporary Latin squares, with experimental period of 21 days, 14 for diet adaptation and 7 for sample collections. The cows were fed with diets isoenergetic \"ad libitum\", with two major nitrogen sources (soybean meal and urea) and two CP levels (14.5 and 16.0%) in diet: A) 16% CP soybean meal (SBM) as a nitrogen source, with 65% RDP; B) 14.5% CP and urea (U) as a nitrogen source, with 70% RDP; C) 16% CP U and 70% RDP; D) 14.5% CP and 65% FS RDP in DM. The milk samples for composition analysis were collected from the 14th to the 17th day of each period. The rumen fluid samples were collected using an esophageal tube , three hours after the morning feeding. The digestibility was determined by means of an internal indicator iADF. There was no effect of diets on the DM intake (kg / day), net energy for lactation (Mcal / day), percentage of digestibility and intake in percentage of body weight. There was interaction between nitrogen source and content of CP on pH and the acetate propionate ratio. There was a trend (P = 0.052) of source of nitrogen for CP (kg / day) in which diets with soybean meal had a higher value when compared with urea diets. Milk fat was higher (4.06%) in diets with urea nitrogen source, the source nitrogen compared with soybeans meal (3.5%).

O objetivo deste estudo foi avaliar a biohidrogenação ruminal e o fluxo intestinal de ácidos graxos em vacas leiteiras suplementadas com diferentes fontes lipídicas. Foram utilizadas 8 vacas da raça Holandesa no terço médio de lactação (180 ± 20 dias em lactação; média ± DP) canuladas no rúmen e abomaso (580 ± 20 kg de peso corporal; media ± DP), agrupadas em dois quadrados latinos 4 x 4 balanceados, que foram alimentadas com as seguintes dietas: 1) Controle (C), dieta a base de milho e farelo de soja; 2) Óleo de soja (OS); 3) Grão de soja in natura (GS); e 4) sais de cálcio de ácidos graxos insaturados (SC). Houve efeito das fontes lipídicas (P<0,05) sobre o consumo de matéria seca, proteína bruta, FDN e CNF, onde os animais submetidos às dietas com estas fontes apresentaram menor consumo. Os valores de ph ruminal foram maiores (P<0,05) para os animais suplementados com as fontes lipídicas. A relação C2/C3, foi menor (P<0,05) nos animais que receberam as dietas com lipídios. A produção de leite, síntese de proteína microbiana e os balanços de energia e nitrogênio não foram influenciados pelas dietas experimentais. Os animais que receberam as dietas contendo fontes lipídicas apresentaram maiores concentrações séricas de colesterol total (P<0,05). A utilização de grão de soja cru integral influenciou positivamente o teor de gordura no leite, e levou a menores concentrações de CLAs no perfil de AG do leite. A digestibilidade da FDN e a taxa de passagem da MS foram menores nos animais submetidos às dietas com fontes lipídicas (P<0,05). O consumo e fluxo abomasal de AG foram maiores (P<0,05) nos animais suplementados com fontes lipídicas. As fontes protegidas (SC e GS), promoveram maior fluxo abomasal de C18:2 e menores taxas de bio-hidrogenação quando comparados com a dieta OS. A utilização de grão de soja cru e integral aumentou o fluxo abomasal de C18:2 com menores alterações nos processos digestórios e no metabolismo animal. / The objective of this study was to evaluate the ruminal biohydrogenation and intestinal flow of fatty acids in dairy cows supplemented with different lipid sources. Eight Holstein cows in mid lactation (180 ± 20 days in milk; mean ± SD) cannulated in the rumen and abomasum (580 ± 20 kg body weight; mean ± SD) were assigned randomly into in two 4 x 4 balanced latin squares, fed with the following diets: 1) control (C) diet based on corn and soybean meal; 2) soybean oil (SO); 3) whole raw soybean (WS); and 4) calcium salts of unsaturated fatty acids (CS). There was effect of lipid sources (P <0.05) on intake of dry matter, crude protein, NDF and NFC, where the animals fed with these sources had lower values. The ruminal pH values were higher (P <0.05) for animals supplemented with lipid sources. The C2 / C3 ratio was lower (P <0.05) in animals fed diets with lipids. Milk production, microbial protein synthesis and energy and nitrogen balances were not influenced by experimental diets. Animals fed diets containing lipid sources had higher serum concentrations of total cholesterol (P <0.05). The use of whole raw soybean influenced positively the fat content in milk, and led to lower concentrations of CLAs in the milk FA profile. NDF digestibility and DM passage rate were lower in animals fed diets with fat sources (P <0.05). Intake and abomasal flow of FA was higher (P <0.05) for animals supplemented with fat sources. Protected sources (CS and WS) promoted greater abomasal flow of C18: 2 and smaller biohydrogenation rate compared to the SO diet. The use of whole raw soybean increased abomasal flow of C18: 2, with less changes in digestive processes and animal metabolism.

O avanço na ciência trouxe novas descobertas sobre mecanismos celulares, o que permitiu o desenvolvimento de novos produtos e serviços acerca do melhoramento genético animal. A tecnologia genômica, embora recente, traz para a atividade leiteira a possibilidade de aumentar os ganhos em seleção genética e a rentabilidade econômica. No Brasil, já são comercializados testes genômicos que possibilitam, por meio da coleta de material genético, uma predição das características genéticas dos bovinos jovens com a identificação de características produtivas dos animais, antes da sua expressão. No entanto, por se tratar de uma tecnologia nova, ainda não se sabe a opinião dos pecuaristas sobre a tecnologia, sobre o melhoramento genético, nem se conhece o nível de conhecimento e tecnificação do produtor. Portanto, a presente pesquisa levantou informações sobre o perfil das propriedades de atividade leiteira passíveis de utilizarem os testes genômicos, identificando suas principais necessidades frente à utilização do serviço. Os dados foram coletados com questionários quantitativos e qualitativos, aplicados de forma aleatória a 100 propriedades produtoras de leite, distribuídas na região do Triângulo Mineiro. Após a coleta, foram realizados testes estatísticos de análise descritiva com tabelas de contingência e correlação, com os dados não paramétricos obtidos. Através destes, identificou-se que as propriedades são heterogêneas, com níveis de tecnificação crescentes e que contam cada vez mais com o apoio da assistência técnica. Parte dos pecuaristas ainda não utilizam ferramentas para melhoria da seleção genética como: inseminação artificial, IATF, TE ou outras e embora os testes genômicos já estejam disponíveis comercialmente, apenas 25% dos entrevistados dizem ter conhecimentos básicos sobre a técnica. Para que os testes genômicos atendam às necessidades do consumidor final e sejam comercializados, é importante que além do aumento na disseminação de conhecimento sobre o produto, o seu preço seja acessível, o produtor sinta confiança no resultado e que os grupo de animais a ser avaliado atenda aos requisitos mínimos exigidos pela tecnologia, para assim, se conseguir utilizar o produto com mais alta acurácia. / The breakthrough in science has brought new discoveries about cellular mechanisms, allowing the development of new products and services about animal genetic improvement. Genomic technology, although recent, brings to dairy activity the possibility of increasing gains in genetic selection and economic profitability. In Brazil, genomic tests are already commercialized, which make it possible, through the collection of genetic material, to predict the genetic characteristics of young cattle with the identification of productive characteristics of the animals before their expression. However, because it is a new technology, the opinion of cattle ranchers about technology, genetic improvement, and the level of knowledge and technification of the producer is not yet known. Therefore, the present research raised information on the profile of dairy activity properties that could use genomic tests, identifying their main needs in relation to the use of the service. The data were collected with quantitative and qualitative questionnaires, randomly applied to 100 milk properties, distributed in the Triângulo Mineiro region. After the collection, statistical tests of descriptive analysis and contingency and correlation tables were performed with the non-parametric data obtained. Through these, it was identified that the properties are heterogeneous, with increasing levels of technification and increasingly rely on the support of technical assistance. Some of the cattle ranchers still do not use tools to improve genetic selection such as artificial insemination, IATF, ET or others, and although genomic tests are already commercially available, only 25% of the interviewees have a basic knowledge of the technique. To sell the genomic tests, is important to understand the needs of the final consumer and to be marketed, it is important that the costumer increases the knowledge of the product, the price need to be accessible, the producer feels confidence in the result and that the groups of animals to be evaluated meet the minimum requirements required by the technology in order to be able to use the product with the highest accuracy.